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HTML::Mason::Devel (3)
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HTML::Mason::Devel - Mason Developer's ManualDESCRIPTION
This manual is written for content developers who knowIf you are the webmaster (or otherwise responsible for the Mason installation), you should also read the administrator's manual. There you will find information about site configuration, performance tuning, component caching, and so on.
If you are a developer just interested in knowing more about Mason's capabilities and implementation, then the administrator's manual is for you too.
We strongly suggest that you have a working Mason to play with as you work through these examples. Other component examples can be found in the "samples/" directory.
While Mason can be used for tasks besides implementing a dynamic web site, that is what most people want to do with Mason, and is thus the focus of this manual.
If you are planning to use Mason outside of the web, this manual will still be useful, of course. Also make sure to read the running outside of mod_perl section of the administrator's manual.
If you are just learning Mason and want to get started quickly, we recommend the following sections:o What Are Components?
o In-Line Perl Sections
o Calling Components
o Top-Level Components
o Passing Parameters
o Initialization and Cleanup (mainly "<%init>")
o Web-Specific Features
o Common Traps
The component - a mix of Perl and
+---------+------------------+ |Masthead | Banner Ad | +---------+------------------+ | | | |+-------+|Text of Article ..| || || | ||Related||Text of Article ..| ||Stories|| | || ||Text of Article ..| |+-------+| | | +------------------+ | | Footer | +---------+------------------+
The top level component decides the overall page layout, perhaps with
This component approach reaps many benefits in a web environment. The first benefit is consistency: by embedding standard design elements in components, you ensure a consistent look and make it possible to update the entire site with just a few edits. The second benefit is concurrency: in a multi-person environment, one person can edit the masthead while another edits the table of contents. A last benefit is reuseability: a component produced for one site might be useful on another. You can develop a library of generally useful components to employ on your sites and to share with others.
Most components emit chunks of
Components receive form and query data from
Mason actually compiles components down to Perl subroutines, so you can debug and profile component-based web pages with standard Perl tools that understand the subroutine concept, e.g. you can use the Perl debugger to step through components, and Devel::DProf to profile their performance.
Here is a simple component example:
<%perl> my $noun = 'World'; my @time = localtime; </%perl> Hello <% $noun %>, % if ( $time[2] < 12 ) { good morning. % } else { good afternoon. % }
After 12 pm, the output of this component is:
Hello World, good afternoon.
This short example demonstrates the three primary ``in-line'' Perl sections. In-line sections are generally embedded within
The parsing rules for these Perl sections are as follows:
- 1.
- Blocks of the form <% xxx %> are replaced with the result of evaluating xxx as a single Perl expression. These are often used for variable replacement. such as 'Hello, <% $name %>!'.
- 2.
- Lines beginning with a '%' character are treated as Perl.
- 3.
Multiline blocks of Perl code can be inserted with the "<%perl>"
.. "</%perl>" tag. The enclosed text is executed as Perl and the return
value, if any, is discarded.
The "<%perl>" tag, like all block tags in Mason, is case-insensitive. It may appear anywhere in the text, and may span any number of lines.
Examples and Recommended Usage
% linesMost useful for conditional and loop structures - if, while, foreach, , etc. - as well as side-effect commands like assignments. To improve readability, always put a space after the '%'. Examples:
o Conditional code
% my $ua = $r->header_in('User-Agent'); % if ($ua =~ /msie/i) { Welcome, Internet Explorer users ... % } elsif ($ua =~ /mozilla/i) { Welcome, Netscape users ... % }

 % foreach $item (@list) {
<% $item %>
 % }

 % while (my ($key,$value) = each(%ENV)) {
 <% $key %>: <% $value %>
 % }

 % foreach my $h (@loh) {
 <% $h->{foo} %>	 <% $h->{bar} %>	 <% $h->{baz} %>
 % }

<% xxx %>
Most useful for printing out variables, as well as more complex expressions. To improve readability, always separate the tag and expression with spaces. Examples:
Dear <% $name %>: We will come to your house at <% $address %> in the fair city of <% $city %> to deliver your $<% $amount %> dollar prize! The answer is <% ($y+8) % 2 %>. You are <% $age < 18 ? 'not' : '' %> permitted to enter this site.
<%perl> xxx </%perl>
Useful for Perl blocks of more than a few lines.
This section describes the various objects in the Mason universe. If you're just starting out, all you need to worry about initially are the request objects.Request Objects
Two global per-request objects are available to all components: $r and $m.$r, the mod_perl request object, provides a Perl
$r->uri # the HTTP request URI $r->header_in(..) # get the named HTTP header line $r->content_type # set or retrieve content-type $r->header_out(..) # set or retrieve an outgoing header $r->content # don't use this one! (see Tips and Traps)
$m, the Mason request object, provides an analogous
Because these are always set inside components, you should not ever define other variables with the same name, or else your code may fail in strange and mysterious ways.
Component Objects
Mason provides an objectNote that for many basic applications all you'll want to do with components is call them, for which no object method is needed. See next section.
System Objects
Many system objects share the work of serving requests in Mason: HTML::Mason::Lexer, HTML::Mason::Compiler, HTML::Mason::Interp, HTML::Mason::Resolver, and HTML::Mason::ApacheHandler are examples. The administrator creates these objects and provides parameters that shape Mason's behavior. As a pure component developer you shouldn't need to worry about or access these objects, but occasionally we'll mention a relevant parameter.CALLING COMPONENTS
Mason pages often are built not from a single component, but from multiple components that call each other in a hierarchical fashion.Components that output HTML
To call one component from another, use the <& &> tag:
<& comp_path, [name=>value, ...] &>
- comp_path:
- The component path. With a leading '/', the path is relative to the component root (comp_root). Otherwise, it is relative to the location of the calling component.
- name => value pairs:
- Parameters are passed as one or more "name => value" pairs, e.g. "player => 'M. Jordan'".
comp_path may be a literal string (quotes optional) or a Perl expression that evaluates to a string. To eliminate the need for quotes in most cases, Mason employs some magic parsing: If the first character is one of "[\w/_.]", comp_path is assumed to be a literal string running up to the first comma or &>. Otherwise, comp_path is evaluated as an expression.
Here are some examples:
# relative component paths <& topimage &> <& tools/searchbox &> # absolute component path <& /shared/masthead, color=>'salmon' &> # this component path MUST have quotes because it contains a comma <& "sugar,eggs", mix=>1 &> # variable component path <& $comp &> # variable component and arguments <& $comp, %args &> # you can use arbitrary expression for component path, but it cannot # begin with a letter or number; delimit with () to remedy this <& (int(rand(2)) ? 'thiscomp' : 'thatcomp'), id=>123 &>
Several request methods also exist for calling components. "$m->comp" performs the equivalent action to <& &>:
$m->comp('/shared/masthead', color=>'salmon');
"$m->scomp" is like the sprintf version of "$m->comp": it returns the component output, allowing the caller to examine and modify it before printing:
my $masthead = $m->scomp('/shared/masthead', color=>'salmon'); $masthead =~ ...; $m->print($masthead);
Component Calls with Content
Components can be used to filter part of the page's content using an extended component syntax.
<&| /path/to/comp &> this is the content </&> <&| comp, arg1 => 'hi' &> filters can take arguments </&> <&| comp &> content can include <% "tags" %> of all kinds </&> <&| comp1 &> nesting is also <&| comp2 &> OK </&> </&> <&| SELF:method1 &> subcomponents can be filters </&>
The filtering component can be called in all the same ways a normal component is called, with arguments and so forth. The only difference between a filtering component and a normal component is that a filtering component is expected to fetch the content by calling $m->content and do something with it.
The ending tag may optionally contain the name of the component, and Mason will verify that it matches the name in the starting tag. This may be helpful when the tags are far apart or nested. To avoid ambiguous situations, this is only allowed when the component name is an unquoted literal (starting with "[\w/_.]"). For anything more complicated, such as "<|& $var &>" or "<&| 'name' &>", the simple "</&>" form must be used.
<&| "outer" &> <&| /inner/comp, arg=>'this' &> <&| .mycomp &> Yada yada yada </& .mycomp > </& /inner/comp > </&>
Here is an example of a component used for localization. Its content is a series of strings in different languages, and it selects the correct one based on a global $lang variable, which could be setup in a site-level autohandler.
<&| /i18n/itext &> <en>Hello, <% $name %> This is a string in English</en> <de>Schoene Gruesse, <% $name %>, diese Worte sind auf Deutsch</de> <pig>ellohay <% substr($name,2).substr($name,1,1).'ay' %>, isthay isay igpay atinlay</pig> </&>
Here is the /i18n/itext component:
<% $text %> <%init> # this assumes $lang is a global variable which has been set up earlier. local $_ = $m->content; my ($text) = m{<$lang>(.*?)</$lang>}; </%init>
You can explicitly check whether a component has passed content by checking the boolean "$m->has_content". This allows you to write a component that will do different things depending on whether it was passed content. However, before overloading a component in this way, consider whether splitting the behavior into two distinct components would work as well.
If a normal component which does not call "$m->content" is called with content, the content will not be output.
If you wrap a filtering component call around the entire component, the result will be functionally similar to a "<%filter>" section. See also Filtering.
Advanced Components Calls with Content
Internally "$m->content" is implemented with a closure containing the part of the component which is the content. In English, that means that any mason tags and perl code in the content are evaluated when "$m->content" is called, and "$m->content" returns the text which would have been output by mason. Because the contents are evaluated at the time that "$m->content" is called, one can write components which act as control structures or which output their contents multiple times with different values for the variables (can you say taglibs?).The tricky part of using filter components as control structures is setting up variables which can be accessed from both the filter component and the content, which is in the component which calls the filter component. The content has access to all variables in the surrounding component, but the filtering component does not. There are two ways to do this: use global variables, or pass a reference to a lexical variable to the filter component.
Here is a simple example using the second method:
% my $var;
 <&| list_items , list => \@items, var => \$var &>
 <% $var %>
 </&>

list_items component:
<%args> @list $var </%args> % foreach (@list) { % $$var = $_; # $var is a reference <% $m->content %> % }
Using global variables can be somewhat simpler. Below is the same example, with $var defined as a global variable. The site administrator must make sure that $var is included in Mason's allow_globals parameter. Local-izing $var within the filter component will allow the list_items component to be nested.

 <&| list_items, list => \@items &>
 <% $var %>
 </&>

list_items component:
<%args> @list </%args> % foreach (@list) { % local $var = $_; <% $m->content %> % }
Besides remembering to include $var in allow_globals, the developers should take care not to use that variable is other places where it might conflict with usage by the filter component. Local-izing $var will also provide some protection against using it in other places.
An even simpler method is to use the $_ variable. It is already global, and is automatically local-ized by the foreach statement:

 <&| list_items, list => \@items &>
 <% $_ %>
 </&>

list_items component:
<%args> @list </%args> % foreach (@list) { <% $m->content %> % }
Components that Return Values
So far you have seen components used solely to outputWhile we will demonstrate how this is done, we strongly encourage you to put code like this in modules instead. There are several reasons why this is a good idea:
- *
- You can re-use this code outside of Mason.
- *
- It is easy to preload module code when running under mod_perl, which can lower memory usage.
- *
- Using Mason components as subroutines is slower than just using modules to do the same thing.
- *
- It's easier to regression test module code.
With that being said, there are times when you may want to write a component which returns a value.
As an example, you might have a component "is_netscape" that analyzes the user agent to determine whether it is a Netscape browser:
<%init> my $ua = $r->header_in('User-Agent'); return ($ua =~ /Mozilla/i && $ua !~ /MSIE/i) ? 1 : 0; </%init>
Because components are implemented underneath with Perl subroutines, they can return values and even understand scalar/list context. e.g. The result of wantarray() inside a component will reflect whether the component was called in scalar or list context.
The <& &> notation only calls a component for its side-effect, and discards its return value, if any. To get at the return value of a component, use the "$m->comp" command:
% if ($m->comp('is_netscape')) { Welcome, Netscape user! % }
Mason adds a "return undef" to the bottom of each component to provide an empty default return value. To return your own value from a component, you must use an explicit "return" statement. You cannot rely on the usual Perl trick of letting return values ``fall through''.
While it is possible for a component to generate output and return values, there is very little reason for a component to do both. For example, it would not be very friendly for "is_netscape" to output ``hi Mom'' while it was computing its value, thereby surprising the "if" statement! Conversely, any value returned by an output generating component would typically be discarded by the <& &> tag that invoked it.
You may sometimes want to have a component call go through all the steps that the initial component call goes through, such as checking for autohandlers and dhandlers. To do this, you need to execute a subrequest.A subrequest is simply a Mason Request object and has all of the methods normally associated with one.
To create a subrequest you simply use the "$m->make_subrequest" method. This method can take any parameters belonging to HTML::Mason::Request, such as autoflush or out_method. Once you have a new request object you simply call its "exec" method to execute it, which takes exactly the same parameters as the "comp" method.
Since subrequests inherit their parent request's parameters, output from a component called via a subrequest goes to the same destination as output from components called during the parent request. Of course, you can change this.
Here are some examples:
<%perl> my $req = $m->make_subrequest( comp => '/some/comp', args => [ id => 172 ] ); $req->exec; </%perl>
If you want to capture the subrequest's output in a scalar, you can simply pass an out_method parameter to "$m->make_subrequest":
<%perl> my $buffer; my $req = $m->make_subrequest ( comp => '/some/comp', args => [ id => 172 ], out_method => \$buffer ); $req->exec; </%perl>
Now $buffer contains all the output from that call to /some/comp.
For convenience, Mason also provides an "$m->subexec" method. This method takes the same arguments as "$m->comp" and internally calls "$m->make_subrequest" and then "exec" on the created request, all in one fell swoop. This is useful in cases where you have no need to override any of the parent request object's attributes.
By default, output from a subrequest appears inline in the calling component, at the point where it is executed. If you wish to do something else, you will need to explicitly override the subrequest's out_method parameter.
Mason Request objects are only designed to handle a single call to "exec". If you wish to make multiple subrequests, you must create a new subrequest object for each one.
The first component invoked for a page (the ``top-level component'') resides within the DocumentRoot and is chosen based on the
Mason converts this
$m->comp('/mktg/prods.html', id=>372)
This component might in turn call other components and execute some Perl code, or it might contain nothing more than static
What happens when a user requests a component that doesn't exist? In this case Mason scans backward through theConsider the following
In this case Mason constructs the following search path:
/newsfeeds/LocalNews/Story1 => no such thing /newsfeeds/LocalNews/dhandler => no such thing /newsfeeds/dhandler => found! (search ends) /dhandler
The found dhandler would read ``LocalNews/Story1'' from "$m->dhandler_arg" and use it as a retrieval key into a database of stories.
Here's how a simple /newsfeeds/dhandler might look:
<& header &> <% $headline %>
 <% $body %> <& footer &> <%init> my $arg = $m->dhandler_arg; # get rest of path my ($section, $story) = split("/", $arg); # split out pieces my $sth = $DBH->prepare (qq{SELECT headline,body FROM news WHERE section = ? AND story = ?); $sth->execute($section, $story); my ($headline, $body) = $sth->fetchrow_array; return 404 if !$headline; # return "not found" if no such story </%init>
By default dhandlers do not get a chance to handle requests to a directory itself (e.g. /newsfeeds). These are automatically deferred to Apache, which generates an index page or a
A component or dhandler that does not want to handle a particular request may defer control to the next dhandler by calling "$m->decline".
When using dhandlers under mod_perl, you may find that sometimes Apache will not set a content type for a response. This usually happens when a dhandler handles a request for a non-existent file or directory. You can add a "<Location>" or "<LocationMatch>" block containing a "SetType" directive to your Apache config file, or you can just set the content type dynamically by calling "$r->content_type".
The administrator can customize the file name used for dhandlers with the dhandler_name parameter.
Autohandlers allow you to grab control and perform some action just before Mason calls the top-level component. This might mean adding a standard header and footer, applying an output filter, or setting up global variables.Autohandlers are directory based. When Mason determines the top-level component, it checks that directory and all parent directories for a component called autohandler. If found, the autohandler is called first. After performing its actions, the autohandler typically calls "$m->call_next" to transfer control to the original intended component.
"$m->call_next" works just like "$m->comp" except that the component path and arguments are implicit. You can pass additional arguments to "$m->call_next"; these are merged with the original arguments, taking precedence in case of conflict. This allows you, for example, to override arguments passed in the
Here is an autohandler that adds a common header and footer to each page underneath its directory:
 <title>McHuffy Incorporated</title>  % $m->call_next;
 Copyright 1999 McHuffy Inc.
Same idea, using components for the header/footer:
<& /shared/header &> % $m->call_next; <& /shared/footer &>
The next autohandler applies a filter to its pages, adding an absolute hostname to relative image URLs:
% $m->call_next; <%filter> s{(]+src=\")/} {$1images.mysite.com/}ig; </%filter>
Most of the time autohandler can simply call "$m->call_next" without needing to know what the next component is. However, should you need it, the component object is available from "$m->fetch_next". This is useful for calling the component manually, e.g. if you want to suppress some original arguments or if you want to use "$m->scomp" to store and process the output.
If more than one autohandler applies to a page, each autohandler gets a chance to run. The top-most autohandler runs first; each "$m->call_next" transfers control to the next autohandler and finally to the originally called component. This allows you, for example, to combine general site-wide templates and more specific section-based templates.
Autohandlers can be made even more powerful in conjunction with Mason's object-oriented style features: methods, attributes, and inheritance. In the interest of space these are discussed in a separate section, Object-Oriented Techniques.
The administrator can customize the file name used for autohandlers with the autohandler_name parameter.
dhandlers vs. autohandlers
dhandlers and autohandlers both provide a way to exert control over a large set of URLs. However, each specializes in a very different application. The key difference is that dhandlers are invoked only when no appropriate component exists, while autohandlers are invoked only in conjunction with a matching component.As a rule of thumb: use an autohandler when you have a set of components to handle your pages and you want to augment them with a template/filter. Use a dhandler when you want to create a set of ``virtual URLs'' that don't correspond to any actual components, or to provide default behavior for a directory.
dhandlers and autohandlers can even be used in the same directory. For example, you might have a mix of real URLs and virtual URLs to which you would like to apply a common template/filter.
This section describes Mason's facilities for passing parameters to components (either fromIn Component Calls
Any Perl data type can be passed in a component call:
<& /sales/header, s => 'dog', l => [2, 3, 4], h => {a => 7, b => 8} &>
This command passes a scalar ($s), a list (@l), and a hash (%h). The list and hash must be passed as references, but they will be automatically dereferenced in the called component.
In HTTP requests
Consider a CGI-style
or an
Accessing Parameters
Component parameters, whether they come from1. Declared named arguments: Components can define an "<%args>" section listing argument names, types, and default values. For example:
<%args> $a @b # a comment %c # another comment $d => 5 $e => $d*2 @f => ('foo', 'baz') %g => (joe => 1, bob => 2) </%args>
Here, $a, @b, and %c are required arguments; the component generates an error if the caller leaves them unspecified. $d, $e, @f and %g are optional arguments; they are assigned the specified default values if unspecified. All the arguments are available as lexically scoped (``my'') variables in the rest of the component.
Arguments are separated by one or more newlines. Comments may be used at the end of a line or on their own line.
Default expressions are evaluated in top-to-bottom order, and one expression may reference an earlier one (as $e references $d above).
Only valid Perl variable names may be used in "<%args>" sections. Parameters with non-valid variable names cannot be pre-declared and must be fetched manually out of the %ARGS hash (see below). One common example of undeclarable parameters are the ``button.x/button.y'' parameters sent for a form submit.
2. %ARGS hash: This variable, always available, contains all of the parameters passed to the component (whether or not they were declared). It is especially handy for dealing with large numbers of parameters, dynamically named parameters, or parameters with non-valid variable names. %ARGS can be used with or without an "<%args>" section, and its contents are unrelated to what you have declared in "<%args>".
Here's how to pass all of a component's parameters to another component:
<& template, %ARGS &>
Parameter Passing Examples
The following examples illustrate the different ways to pass and receive parameters.1. Passing a scalar id with value 5.
In a URL: /my/URL?id=5 In a component call: <& /my/comp, id => 5 &> In the called component, if there is a declared argument named... $id, then $id will equal 5 @id, then @id will equal (5) %id, then an error occurs In addition, $ARGS{id} will equal 5.
2. Passing a list colors with values red, blue, and green.
In a URL: /my/URL?colors=red&colors=blue&colors=green In an component call: <& /my/comp, colors => ['red', 'blue', 'green'] &> In the called component, if there is a declared argument named... $colors, then $colors will equal ['red', 'blue', 'green'] @colors, then @colors will equal ('red', 'blue', 'green') %colors, then an error occurs In addition, $ARGS{colors} will equal ['red', 'blue', 'green'].
3. Passing a hash grades with pairs Alice => 92 and Bob => 87.
In a URL: /my/URL?grades=Alice&grades=92&grades=Bob&grades=87 In an component call: <& /my/comp, grades => {Alice => 92, Bob => 87} &> In the called component, if there is a declared argument named... @grades, then @grades will equal ('Alice', 92, 'Bob', 87) %grades, then %grades will equal (Alice => 92, Bob => 87) In addition, $grade and $ARGS{grades} will equal ['Alice',92,'Bob',87] in the URL case, or {Alice => 92, Bob => 87} in the component call case. (The discrepancy exists because, in a query string, there is no detectable difference between a list or hash.)
Using @_ instead
If you don't like named parameters, you can pass a traditional list of ordered parameters:
<& /mktg/prods.html', 'dog', [2, 3, 4], {a => 7, b => 8} &>
and access them as usual through Perl's @_ array:
my ($scalar, $listref, $hashref) = @_;
In this case no "<%args>" section is necessary.
We generally recommend named parameters for the benefits of readability, syntax checking, and default value automation. However using @_ may be convenient for very small components, especially subcomponents created with "<%def>".
Before Mason 1.21, @_ contained copies of the caller's arguments. In Mason 1.21 and beyond, this unnecessary copying was eliminated and @_ now contains aliases to the caller's arguments, just as with regular Perl subroutines. For example, if a component updates $_[0], the corresponding argument is updated (or an error occurs if it is not updateable).
Most users won't notice this change because "<%args>" variables and the %ARGS hash always contain copies of arguments.
See perlsub for more information on @_ aliasing.
The following sections contain blocks of Perl to execute at specific times.<%init>
This section contains initialization code that executes as soon as the component is called. For example: checking that a user is logged in; selecting rows from a database into a list; parsing the contents of a file into a data structure.Technically an "<%init>" block is equivalent to a "<%perl>" block at the beginning of the component. However, there is an aesthetic advantage of placing this block at the end of the component rather than the beginning.
We've found that the most readable components (especially for non-programmers) contain
 <title><% $headline %></title>
<% $headline %>

By <% $author %>, <% $date %>
 <% $body %>   <%init> # Fetch article from database my $dbh = DBI::connect ...; my $sth = $dbh->prepare("select * from articles where id = ?"); $sth->execute($article_id); my ($headline, $date, $author, $body) = $sth->fetchrow_array; # Massage the fields $headline = uc($headline); my ($year, $month, $day) = split('-', $date); $date = "$month/$day"; </%init> <%args> $article_id </%args>
This section contains cleanup code that executes just before the component exits. For example: closing a database connection or closing a file handle.A "<%cleanup>" block is equivalent to a "<%perl>" block at the end of the component. This means it will
If you need code that is guaranteed to run when the component or request exits, consider using a mod_perl cleanup handler, or creating a custom class with a
This code executes once when the component is loaded. Variables declared in this section can be seen in all of a component's code and persist for the lifetime of the component.This section is useful for declaring persistent component-scoped lexical variables (especially objects that are expensive to create), declaring subroutines (both named and anonymous), and initializing state.
This code does not run inside a request context. You cannot call components or access $m or $r from this section. Also, do not attempt to "return()" from a "<%once>" section; the current compiler cannot properly handle it.
Normally this code will execute individually from every
<%once> my $dbh; # declare but don't assign ... </%once> <%init> $dbh ||= DBI::connect ... ... </%init>
In addition, using $m or $r in this section will not work in a preloaded component, because neither of those variable exist when a component is preloaded.
As with "<%once>", lexical ("my") variables declared in this section can be seen in all the rest of a component's code: the main body, subcomponents, and methods. However, unlike "<%once>", the code runs once per request (whenever the component is used) and its variables last only until the end of the request.A "<%shared>" section is useful for initializing variables needed in, say, the main body and one more subcomponents or methods. See Object-Oriented Techniques for an example of usage.
It's important to realize that you do not have access to the %ARGS hash or variables created via an "<%args>" block inside a shared section. However, you can access arguments via $m->request_args.
Additionally, you cannot call a components' own methods or subcomponents from inside a "<%shared>", though you can call other components.
Avoid using "<%shared>" for side-effect code that needs to run at a predictable time during page generation. You may assume only that "<%shared>" runs just before the first code that needs it and runs at most once per request.
In the current implementation, the scope sharing is done with closures, so variables will only be shared if they are visible at compile-time in the other parts of the component. In addition, you can't rely on the specific destruction time of the shared variables, because they may not be destroyed until the first time the "<%shared>" section executes in a future request. "<%init>" offers a more predictable execution and destruction time.
Currently any component with a "<%shared>" section incurs an extra performance penalty, because Mason must recreate its anonymous subroutines the first time each new request uses the component. The exact penalty varies between systems and for most applications will be unnoticeable. However, one should avoid using "<%shared>" when patently unnecessary, e.g. when an "<%init>" would work just as well.
Do not attempt to "return()" from a "<%shared>" section; the current compiler cannot properly handle it.
<%def name>
Each instance of this section creates a subcomponent embedded inside the current component. Inside you may place anything that a regular component contains, with the exception of "<%def>", "<%method>", "<%once>", and "<%shared>" tags.The name consists of characters in the set "[\w._-]". To call a subcomponent simply use its name in <& &> or "$m->comp". A subcomponent can only be seen from the surrounding component.
If you define a subcomponent with the same name as a file-based component in the current directory, the subcomponent takes precedence. You would need to use an absolute path to call the file-based component. To avoid this situation and for general clarity, we recommend that you pick a unique way to name all of your subcomponents that is unlikely to interfere with file-based components. A commonly accepted practice is to start subcomponent names with ``.''.
While inside a subcomponent, you may use absolute or relative paths to call file-based components and also call any of your ``sibling'' subcomponents.
The lexical scope of a subcomponent is separate from the main component. However a subcomponent can declare its own "<%args>" section and have relevant values passed in. You can also use a "<%shared>" section to declare variables visible from both scopes.
In the following example, we create a ``.link'' subcomponent to produce a standardized hyperlink:
<%def .link> <a href="www<% $site %>.com"><% $label %> <%args> $site $label=>ucfirst($site) </%args> </%def> Visit these sites:

<& .link, site=>'yahoo' &>

<& .link, site=>'cmp', label=>'CMP Media' &>

<& .link, site=>'excite' &>

<%method name>
Each instance of this section creates a method embedded inside the current component. Methods resemble subcomponents in terms of naming, contents, and scope. However, while subcomponents can only be seen from the parent component, methods are meant to be called from other components.There are two ways to call a method. First, via a path of the form ``comp:method'':
<& /foo/bar:method1 &> $m->comp('/foo/bar:method1');
Second, via the call_method component method:
my $comp = $m->fetch_comp('/foo/bar'); ... $comp->call_method('method1');
Methods are commonly used in conjunction with autohandlers to make templates more flexible. See Object-Oriented Techniques for more information.
You cannot create a subcomponent and method with the same name. This is mostly to prevent obfuscation and accidental errors.
The "<%flags>" and "<%attr>" sections consist of key/value pairs, one per line, joined by '=>'. In each pair, the key must be any valid Perl ``bareword identifier'' (made of letters, numbers, and the underscore character), and the value may be any scalar value, including references. An optional comment may follow each line.<%flags>
Use this section to set official Mason flags that affect the current component's behavior.Currently there is only one flag, "inherit", which specifies the component's parent in the form of a relative or absolute component path. A component inherits methods and attributes from its parent; see Object-Oriented Techniques for examples.
<%flags> inherit=>'/site_handler' </%flags>
Use this section to assign static key/value attributes that can be queried from other components.
<%attr> color => 'blue' fonts => [qw(arial geneva helvetica)] </%attr>
To query an attribute of a component, use the "attr" method:
my $color = $comp->attr('color')
where $comp is a component object.
Mason evaluates attribute values once when loading the component. This makes them faster but less flexible than methods.
This section describes several ways to apply filtering functions over the results of the current component. By separating out and hiding a filter that, say, changes<%filter> section
The "<%filter>" section allows you to arbitrarily filter the output of the current component. Upon entry to this code, $_ contains the component output, and you are expected to modify it in place. The code has access to component arguments and can invoke subroutines, call other components, etc.This simple filter converts the component output to
<%filter> tr/a-z/A-Z/ </%filter>
The following navigation bar uses a filter to ``unlink'' and highlight the item corresponding to the current page:
Home | Products | Background | Financials | Tech Support | Contact Us <%filter> my $uri = $r->uri; s{(.*?)} {$1}i; </%filter>
This allows a designer to code such a navigation bar intuitively without "if" statements surrounding each link! Note that the regular expression need not be very robust as long as you have control over what will appear in the body.
A filter block does not have access to variables declared in a component's "<%init>" section, though variables declared in the "<%args>", "<%once>" or "<%shared>" blocks are usable in a filter.
It should be noted that a filter cannot rely on receiving all of a component's output at once, and so may be called multiple times with different chunks of output. This can happen if autoflush is on, or if a filter-containing component, or the components it calls, call the "$m->flush_buffer()" method.
You should never call Perl's "return()" function inside a filter section, or you will not see any output at all.
You can use Component Calls with Content if you want to filter specific parts of a component rather than the entire component.
There are several ways to place comments in components, i.e. arbitrary text that is ignored by the parser.<%doc>
Text in this section is treated as a comment and ignored. Most useful for a component's main documentation. One can easily write a program to sift through a set of components and pull out their "<%doc>" blocks to form a reference page.<% # comment... %>
A "<% %>" tag is considered a comment if all of its lines are either whitespace, or begin with a '#' optionally preceded by whitespace. For example,
<% # This is a single-line comment %> <% # This is a # multi-line comment %>
%# comment
Because a line beginning with "%" is treated as Perl, "%#" automatically works as a comment. However we prefer the "<% # comment %>" form over "%#", because it stands out a little more as a comment and because it is more flexible with regards to preceding whitespace.% if (0) { }
Anything between these two lines
% if (0) { ... % }
will be skipped by Mason, including component calls. While we don't recommend this for comments per se, it is a useful notation for ``commenting out'' code that you don't want to run.
HTML/XML/... comments
- *
- They will be sent to the client and appear in the source of the page.
- *
They do not block component calls and other code from running,
so don't try to use them to comment out code!

Text in this section is printed as-is with all Mason syntax ignored. This is useful, for example, when documenting Mason itself from a component:
<%text> % This is an example of a Perl line. <% This is an example of an expression block. %> </%text>
This works for almost everything, but doesn't let you output "</%text>" itself! When all else fails, use "$m->print":
% $m->print('The tags are <%text> and </%text>.');
Escaping expressions
Mason has facilities for escaping the output from "<% %>" tags, on either a site-wide or a per-expression basis.Any "<% %>" expression may be terminated by a '|' and one or more escape flags (plus arbitrary whitespace), separated by commas:
<% $file_data |h %>
The current valid flags are:
- *
HTML('<' => '<', etc.) using "HTML::Entities::encode()". Before Perl 5.8.0 this module assumes that text is in theISO-8859-1character set; see the next section for how to override this escaping. After 5.8.0, the encoding assumes that text is in Unicode. - *
Escape a
URLquery string (':' => '%3A', etc.) - all but [a-zA-Z0-9_.-] - *
This is a special flag indicating that the default escape flags should not be used for this substitution.
The administrator may specify a set of default escape flags via the default_escape_flags parameter. For example, if the administrator sets default_escape_flags to "['h']", then all <% %> expressions will automatically be HTML-escaped. In this case you would use the "n" flag to turn off HTML-escaping for a specific expression:
<% $html_block |n %>
Multiple escapes can be specified as a comma-separated list:
<% $uri | u, n %>
The old pre-defined escapes, 'h', 'u', and 'n', can be used without commas, so that this is legal:
<% $uri | un %>
However, this only works for these three escapes, and no others. If you are using user-defined escapes as well, you must use a comma:
<% $uri | u, add_session %>
User-defined Escapes
Besides the default escapes mentioned above, it is possible for the user to define their own escapes or to override the built-in 'h' and 'u' escapes.
This is done via the Interp object's escape_flags parameter or set_escape() method. Escape names may be any number of characters as long as it matches the regex "/^[\w-]+$/". The one exception is that you cannot override the 'n' flag.
Each escape flag is associated with a subroutine reference. The subroutine should expect to receive a scalar reference, which should be manipulated in place. Any return value from this subroutine is ignored.
Escapes can be defined at any time but using an escape that is not defined will cause an error when executing that component.
A common use for this feature is to override the built-in
PerlSetVar MasonEscapeFlags "h => \&HTML::Mason::Escapes::basic_html_escape"
Or, in a top-level autohandler:
$m->interp->set_escape( h => \&HTML::Mason::Escapes::basic_html_escape );
Or you could write your own escape function for a particular encoding:
$ah->interp->set_escape( h => \&my_html_escape );
And of course this can be used for all sorts of other things, like a naughty words filter for the easily offended:
$interp->set_escape( 'no-naughty' => \&remove_naughty_words );
Manually applying escapes
You can manually apply one or more escapes to text using the Interp object's "apply_escapes()" method. e.g.
$m->interp->apply_escapes( 'some html content', 'h' );
Backslash at end of line
A backslash (\) at the end of a line suppresses the newline. In

 foo % if (1) { bar % } baz

foo bar baz
because of the newlines on lines 2 and 4. (Lines 3 and 5 do not generate a newline because the entire line is taken by Perl.) To suppress the newlines:

 foo\ % if (1) { bar\ % } baz

which prints
Mason's data caching interface allows components to cache the results of computation for improved performance. Anything may be cached, from a block ofEach component gets its own private, persistent data cache. Except under special circumstances, one component does not access another component's cache. Each cached value may be set to expire at a certain time.
Data caching is implemented on top of one of two external caching APIs: "Cache::Cache", which is stable but has not changed in years, or "CHI", which has picked up where "Cache::Cache" has left off and is actively maintained. You control which one Mason uses with the data_cache_api parameter. "Cache::Cache" is the default for backward compatibility reasons, but we recommend "CHI" for anyone doing serious caching. The APIs are very similar for Mason users, so that most of the information below applies to both; any differences are noted.
Basic Usage
The "$m->cache" method returns a cache object representing the cache for this component. Here's the typical usage of "$m->cache":
my $result = $m->cache->get('key'); if (!defined($result)) { ... compute $result ... $m->cache->set('key', $result); }
"$m->cache->get" attempts to retrieve this component's cache value. If the value is available it is placed in $result. If the value is not available, $result is computed and stored in the cache by "$m->cache->set".
Multiple Keys/Values
A cache can store multiple key/value pairs. A value can be anything serializable by "Storable", from a simple scalar to an arbitrary complex list or hash reference:
$m->cache->set(name => $string); $m->cache->set(friends => \@list); $m->cache->set(map => \%hash);
You can fetch all the keys in a cache with
my @idents = $m->cache->get_keys;
It should be noted that Mason reserves all keys beginning with "__mason" for its own use.
You can pass an optional third argument to "$m->cache->set" indicating when the item should expire:
$m->cache->set('name1', $string1, '5 min'); # Expire in 5 minutes $m->cache->set('name2', $string2, '3h'); # Expire in 3 hours
To change the expiration time for a piece of data, call "set" again with the new expiration. To expire an item immediately, use "$m->cache->remove".
You can also specify an expiration condition when you fetch the item, using the expire_if option:
my $result = $m->cache->get('key', expire_if=>sub { $_[0]->get_created_at < (stat($file))[9] });
expire_if takes an anonymous subroutine, which is called with the cache object as its only parameter. If the subroutine returns a true value, the item is expired. In the example above, we expire the item whenever a certain file changes.
Finally, you can expire a cache item from an external script; see Accessing a Cache Externally below.
Avoiding Concurrent Recomputation
The code shown in ``Basic Usage'' above,
my $result = $m->cache->get('key'); if (!defined($result)) { ... compute $result ... $m->cache->set('key', $result); }
can suffer from a kind of race condition for caches that are accessed frequently and take a long time to recompute.
Suppose that a particular cache value is accessed five times a second and takes three seconds to recompute. When the cache expires, the first process comes in, sees that it is expired, and starts to recompute the value. The second process comes in and does the same thing. This sequence continues until the first process finishes and stores the new value. On average, the value will be recomputed and written to the cache 15 times!
One solution is the busy_lock flag:
my $result = $m->cache->get('key', busy_lock=>'30 sec');
In this case, when the value cannot be retrieved, "get()" sets the expiration time of the value 30 seconds in the future before returning "undef". This tells the first process to compute the new value while causing subsequent processes to use the old value for 30 seconds.
Should the 30 seconds expire before the first process is done, a second process will start computing the new value while setting the expiration time yet another 30 seconds in the future, and so on.
The disadvantage of this solution is that multiple writes to the cache will be performed for each "set()".
Another solution, available only if you are using "CHI", is "expires_variance" which will create a variable time window during which expiration may occur. See the "CHI" documentation for details.
Caching All Output
Occasionally you will need to cache the complete output of a component. For this purpose, Mason offers the "$m->cache_self" method. This method causes Mason to check to see if this component has already been run and its output cached. If this is the case, this output is simply sent as output. Otherwise, the component run normally and its output and return value cached.It is typically used right at the top of an "<%init>" section:
<%init> return if $m->cache_self(key => 'fookey', expires_in => '3 hours', ... <other cache options> ...); ... <rest of init> ... </%init>
A full list of parameters and examples are available in the cache_self section of the Request manual.
Cache Object
"$m->cache->get_object" returns a "Cache::Object" or "CHI::CacheObject" associated with a particular key. You can use this to retrieve useful meta-data:
my $co = $m->cache->get_object('name1'); $co->get_created_at(); # when was object stored in cache $co->get_expires_at(); # when does object expire
Choosing a Cache Subclass - with Cache::Cache
The "Cache::Cache"By default "$m->cache" uses "FileCache", but you can override this with the cache_class keyword. The value must be the name of a "Cache::Cache" subclass; the prefix ``Cache::'' need not be included. For example:
my $result = $m->cache(cache_class => 'MemoryCache')->get('key'); $m->cache(cache_class => 'MemoryCache')->set(key => $result);
You can even specify different subclasses for different keys in the same component. Just make sure the correct value is passed to all calls to "$m->cache"; Mason does not remember which subclass you have used for a given component or key.
The administrator can set the default cache subclass used by all components with the data_cache_defaults parameter.
Choosing a Cache Subclass - with CHI
The "CHI" "CHI::Driver::File" is the default, but you can override this with the driver keyword. The value must be the name of a "CHI::Driver" subclass; the prefix ``CHI::Driver::'' need not be included. For example:
my $cache = $m->cache(driver => 'Memcached', servers => [ ... ]); my $result = $cache->get('key'); $cache->set(key => $result);
You can even specify different subclasses for different keys in the same component. Just make sure the correct value is passed to all calls to "$m->cache"; Mason does not remember which subclass you have used for a given component or key.
The administrator can set the default cache subclass used by all components with the data_cache_defaults parameter.
Accessing a Cache Externally
To access a component's cache from outside the component (e.g. in an external Perl script), you'll need have the following information:- *
- the namespace associated with the component. For "Cache::Cache", the function "HTML::Mason::Utils::data_cache_namespace", given a component id (usually just the component path), returns the namespace. For "CHI", the component id/path itself is the namespace.
- *
- the cache_root, for file-based caches only. Defaults to the ``cache'' subdirectory under the Mason data directory.
Given this information you can get a handle on the component's cache. For example, the following code removes a cache item for component /foo/bar, assuming the data directory is /usr/local/www/mason and you are using the default file backend:
use HTML::Mason::Utils qw(data_cache_namespace); # With Cache::Cache my $cache = new Cache::FileCache ( { namespace => data_cache_namespace("/foo/bar"), cache_root => "/usr/local/www/mason/cache" } ); # With CHI my $cache = CHI->new ( driver => 'File', namespace => "/foo/bar", cache_root => "/usr/local/www/mason/cache" ); # Remove one key $cache->remove('key1'); # Remove all keys $cache->clear;
Mason 1.0x Cache API
For users upgrading from 1.0x and earlier, any existing $m->cache
code will be incompatible with the new The "access_data_cache" function is no longer available; this will need to be converted to use "Cache::Cache" directly, as described in the previous section.
Sending HTTP Headers
Mason automatically sends To determine the exact header behavior on your system, you need to know whether your server's default is to have autoflush on or off. Your administrator should have this information. If your administrator doesn't know then it is probably off, the default.
With autoflush off the header situation is extremely simple: Mason waits until the very end of the request to send headers. Any component can modify or augment the headers.
With autoflush on the header situation is more complex. Mason will send headers just before sending the first output. This means that if you want to affect the headers with autoflush on, you must do so before any component sends any output. Generally this takes place in an "<%init>" section.
For example, the following top-level component calls another component to see whether the user has a cookie; if not, it inserts a new cookie into the header.
<%init> my $cookie = $m->comp('/shared/get_user_cookie'); if (!$cookie) { $cookie = new CGI::Cookie (...); $r->header_out('Set-cookie' => $cookie); } ... </%init>
With autoflush off this code will always work. Turn autoflush on and this code will only work as long as /shared/get_user_cookie doesn't output anything (given its functional nature, it shouldn't).
The administrator can turn off automatic header sending via the auto_send_headers parameter. You can also turn it off on individual pages with
Returning HTTP Status
The value returned from the top-most component becomes the status code
of the request. If no value is explicitly returned, it defaults to Simply returning an error status (such as 404) from the top-most component has two problems in practice. First, the decision to return an error status often resides further down in the component stack. Second, you may have generated some content by the time this decision is made. (Both of these are more likely to be true when using autohandlers.)
Thus the safer way to generate an error status is
$m->clear_buffer; $m->abort($status);
"$m->abort" bypasses the component stack and ensures that $status is returned from the top-most component. It works by throwing an exception. If you wrapped this code (directly or indirectly) in an eval, you must take care to rethrow the exception, or the status will not make it out:
eval { $m->comp('...') }; if (my $err = $@) { if ($m->aborted) { die $err; } else { # deal with non-abort exceptions } }
Filters and $m->abort
A filter section will still be called after a component aborts with "$m->abort". You can always check "$m->aborted" in your "<%filter>" block if you don't want to run the filter after an abort.
<%filter> unless ( $m->aborted ) { $_ .= ' filter stuff'; } </%filter>
External Redirects
Because it is so commonly needed, Mason 1.1x and on provides an external redirect method:
$m->redirect($url); # Redirects with 302 status
This method uses the clear_buffer/abort technique mentioned above, so the same warnings apply regarding evals.
Also, if you generate any output after calling "$m->redirect", then this output will be sent, and will break the redirect. For example:
% eval { $m->comp('redirect', ...) }; % die $@ if $@;
The blank line between the two Perl lines is new output generated after the redirect. Either remove it or call "$m->clear_buffer" immediately before calling "die()".
Internal Redirects
There are two ways to perform redirects that are invisible to the client.First, you can use a Mason subrequest (see ``Subrequests''). This only works if you are redirecting to another Mason page.
Second, you can use Apache's internal_redirect method, which works whether or not the new
$r->internal_redirect($url); $m->auto_send_headers(0); $m->clear_buffer; $m->abort;
The last three lines prevent the original request from accidentally generating extra headers or content.
You can use the perl debugger in conjunction with a live mod_perl/Mason server with the help of Apache::DB, available fromThe only tricky thing about debugging Mason pages is that components are implemented by anonymous subroutines, which are not easily breakpoint'able. To remedy this, Mason calls the dummy subroutine "debug_hook" at the beginning of each component. You can breakpoint this subroutine like so:
b HTML::Mason::Request::debug_hook
debug_hook is called with two parameters: the current Request object and the full component path. Thus you can breakpoint specific components using a conditional on $_[1]:
b HTML::Mason::Request::debug_hook $_[1] =~ /component name/
You can avoid all that typing by adding the following to your ~/.perldb file:
# Perl debugger aliases for Mason $DB::alias{mb} = 's/^mb\b/b HTML::Mason::Request::debug_hook/';
which reduces the previous examples to just:
mb mb $_[1] =~ /component name/
Mason normally inserts '#line' directives into compiled components so that line numbers are reported relative to the source file. Depending on your task, this can be a help or a hindrance when using the debugger. The administrator can turn off '#line' directives with the use_source_line_numbers parameter.
Mason uses "Log::Any" to log various events, such as the start and end of each request and each component call. You can also log to "Log::Any" from a component with the "$m->log" method. e.g.
$m->log->error("Something bad happened!"); $m->log->debugf("Arguments for '%s' were '%s'", $func, \%args) if $m->log->is_debug;
See "Log::Any::Adapter" for how to direct these logs to an output of your choice.
Earlier you learned how to assign a common template to an entire hierarchy of pages using autohandlers. The basic template looks like:
header HTML % $m->call_next; footer HTML
However, sometimes you'll want a more flexible template that adjusts to the requested page. You might want to allow each page or subsection to specify a title, background color, or logo image while leaving the rest of the template intact. You might want some pages or subsections to use a different template, or to ignore templates entirely.
These issues can be addressed with the object-oriented style primitives introduced in Mason 0.85.
Note: we use the term object-oriented loosely. Mason borrows concepts like inheritance, methods, and attributes from object methodology but implements them in a shallow way to solve a particular set of problems. Future redesigns may incorporate a deeper object architecture if the current prototype proves successful.
Determining inheritance
Every component may have a single parent. The default parent is a component named "autohandler" in the closest parent directory. This rule applies to autohandlers too: an autohandler may not have itself as a parent but may have an autohandler further up the tree as its parent.You can use the "inherit" flag to override a component's parent:
<%flags> inherit => '/foo/bar' </%flags>
If you specify undef as the parent, then the component inherits from no one. This is how to suppress templates.
Currently there is no way to specify a parent dynamically at run-time, or to specify multiple parents.
Content wrapping
At page execution time, Mason builds a chain of components from the called component, its parent, its parent's parent, and so on. Execution begins with the top-most component; calling "$m->call_next" passes control to the next component in the chain. This is the familiar autohandler ``wrapping'' behavior, generalized for any number of arbitrarily named templates.Accessing methods and attributes
A template can access methods and/or attributes of the requested page. First, use "$m->request_comp" to get a handle on the appropriate component:
my $self = $m->request_comp;
$self now refers to the component corresponding to the requested page (the component at the end of the chain).
To access a method for the page, use "call_method":
This looks for a method named 'header' in the page component. If no such method exists, the chain of parents is searched upwards, until ultimately a ``method not found'' error occurs. Use 'method_exists' to avoid this error for questionable method calls:
if ($self->method_exists('header')) { ...
The component returned by the "$m->request_comp" method never changes during request execution. In contrast, the component returned by "$m->base_comp" may change several times during request execution.
When execution starts, the base component is the same as the requested component. Whenever a component call is executed, the base component may become the component that was called. The base component will change for all component calls except in the following cases:
- *
A component is called via its component object rather than its path,
for example:
<& $m->fetch_comp('/some/comp'), foo => 1 &>
- *
- A subcomponent (defined with "<%def>") is called.
- *
- A method is called via the use of "SELF:", "PARENT:", or "REQUEST:". These are covered in more detail below.
In all other cases, the base component is the called component or the called component's owner component if that called component is a method.
As hinted at above, Mason provides a shortcut syntax for method calls.
If a component call path starts with "SELF:", then Mason will start looking for the method (the portion of the call after "SELF:"), in the base component.
<& SELF:header &> $m->comp('SELF:header')
If the call path starts with "PARENT:", then Mason will start looking in the current component's parent for the named method.
<& PARENT:header &> $m->comp('PARENT:header')
In the context of a component path,
If the call path begins with "REQUEST:", then Mason looks for the method in the requested component.
The rules for attributes are similar. To access an attribute for the page, use "attr":
my $color = $self->attr('color')
This looks for an attribute named 'color' in the $self component. If no such attribute exists, the chain of parents is searched upwards, until ultimately an ``attribute not found'' error occurs. Use "attr_exists" or "attr_if_exist" to avoid this error for questionable attributes:
if ($self->attr_exists('color')) { ... my $color = $self->attr_if_exists('color'); # if it doesn't exist $color is undef
Sharing data
A component's main body and its methods occupy separate lexical scopes. Variables declared, say, in the "<%init>" section of the main component cannot be seen from methods.To share variables, declare them either in the "<%once>" or "<%shared>" section. Both sections have an all-inclusive scope. The "<%once>" section runs once when the component loads; its variables are persistent for the lifetime of the component. The "<%shared>" section runs once per request (when needed), just before any code in the component runs; its variables last only til the end of the request.
In the following example, various sections of code require information about the logged-in user. We use a "<%shared>" section to fetch these in a single request.
<%attr> title=>sub { "Account for $full_name" } </%attr> <%method lefttoc> <% $full_name %> (Log out)
 ... </%method> Welcome, <% $fname %>. Here are your options: <%shared> my $dbh = DBI::connect ...; my $user = $r->connection->user; my $sth = $dbh->prepare("select lname,fname, from users where user_id = ?"); $sth->execute($user); my ($lname, $fname) = $sth->fetchrow_array; my $full_name = "$first $last"; </%shared>
"<%shared>" presents a good alternative to "<%init>" when data is needed across multiple scopes. Outside these situations, "<%init>" is preferred for its slightly greater speed and predictable execution model.
Let's say we have three components:
/autohandler /products/autohandler /products/index.html
and that a request comes in for /products/index.html.
/autohandler contains a general template for the site, referring to a number of standard methods and attributes for each page:
 <title><& SELF:title &></title>  <body style="<% $self->attr('body_style') %>"> <& SELF:header &>
 % $m->call_next;
 <& SELF:footer &>  <%init> my $self = $m->base_comp; ... </%init> <%attr> body_style => 'standard' </%attr> <%method title> McGuffey Inc. </%method> <%method header>
<& SELF:title &>
 </%method> <%method footer> </%method>
Notice how we provide defaults for each method and attribute, even if blank.
/products/autohandler overrides some attributes and methods for the /products section of the site.
<%attr> body_style => 'plain' </%attr> <%method title> McGuffey Inc.: Products </%method> % $m->call_next;
Note that this component, though it only defines attributes and methods, must call "$m->call_next" if it wants the rest of the chain to run.
/products/index.html might override a few attributes, but mainly provides a primary section for the body.
- Do not call $r->content or new CGI
Mason calls "$r->content" itself to read request input, emptying
the input buffer and leaving a trap for the unwary: subsequent calls
to "$r->content" hang the server. This is a mod_perl ``feature'' that
may be fixed in an upcoming release.
For the same reason you should not create a
CGIobject likemy $query = new CGI;
when handling a
POST; theCGImodule will try to reread request input and hang. Instead, create an empty object:my $query = new CGI ("");
such an object can still be used for all of
CGI's usefulHTMLoutput functions. Or, if you really want to useCGI's input functions, initialize the object from %ARGS:my $query = new CGI (\%ARGS);


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Jodi Arias gives another interview from jailhouse speaking about Travis Alexander murder trial
Jodi Arias gave a surprise jailhouse interview just hours after a jury began deliberating her fate, speaking out about her murder trial, her many fights with her legal team and her belief that she "deserves a second chance at freedom someday".
Jodi Arias repeated many of her claims from previous interviews, testimony on the witness stand and her statements to the jury earlier on Tuesday as she pleaded for mercy.
Her further stints of self-promotion came as the jury were unable to reach a decision on Wednesday on whether she should be sentenced to death.
The judge sent the jury back out to deliberate until 4.30 p.m. (MST). If jurors are unable to agree, then the judge will declare a mistrial for death penalty phase only and a new jury will be brought in.
Jodi Arias also provided some new information about her case and how she believed her lawyers let her down by not calling more witnesses who could have bolstered her claims that she was a victim of domestic violence at the hands of Travis Alexander.
She was convicted last week of first-degree murder in the June 2008 stabbing and shooting death of her one-time lover in what prosecutors described as a cold, calculated killing carried out in a jealous rage. Jodi Arias has maintained all along it was self-defense.
The jury began deliberating Tuesday as they worked to determine whether she should live or die for her crime. If the jury opts for a life sentence, the judge will have the option of determining whether she spends the rest of her days behind bars or is eligible for release after 25 years.
Jodi Arias acknowledged it was unlikely she would ever be released, but believed she deserves a second chance.
Following her conviction last week, Jodi arias told a local TV station that she preferred the death penalty.
She said on Tuesday night that she changed her mind after a tearful meeting with family members that same day, realizing that her death would only cause them more pain.
"I felt like by asking for death, it's like asking for assisted suicide and I didn't want to do that to my family," Jodi Arias said.
Jodi Arias said she fought from the beginning to keep cameras out of the courtroom to limit the media spectacle, and believes that the jury should have been sequestered. She stated flatly that she did not receive a fair trial.
"The prosecutor has accused me of wanting to be famous, which is not true," she said.
However, Jodi Arias has sought the spotlight at every turn, providing TV interviews and even using a third-party to tweet throughout the trial.
Jodi Arias repeated her claims that she never wanted to go to trial in the first place but instead wanted to reach a deal with prosecutors on a second-degree murder count that would have carried a maximum of 22 years in prison. However, she said, "no deal was offered".
She gave the interviews on Tuesday after the judge lifted an order barring jail officials from arranging any media requests.
The judge did not elaborate on the reason for the ruling, but Maricopa County Sheriff Joe Arpaio's office quickly began making the media arrangements that lasted late into the night.
A shackled Jodi Arias wore makeup for the interviews and showed up in a jail classroom with a comb in hand as she fixed her hair for the cameras. When pressed for details on some of her conflicting stories, she was mostly evasive, citing advice from her attorneys and possible pending appeals.
She was also asked about the conflicts she had had with her two court-appointed lawyers, Kirk Nurmi and Jennifer Willmott.
Jodi Arias said she wanted at least three people called as witnesses who could have testified to having seen bruises on her neck "when I was choked out" by Travis Alexander but she said she was rebuffed by her lawyers.
The prosecutor insisted her claims of self-defense were an exaggerated attempt to avoid being convicted.
Jodi Arias said her lawyers "felt a little betrayed" and blindsided by her post-conviction interview but that they gave their blessings for Tuesday night's interviews, warning her to be cautious.
She said she sometimes wishes she'd never met Alexander, "just because of how ultimately everything ended and I say that for his sake and mine – not just a selfish thing".
Jodi Arias said if the attack never occurred and she never crossed paths with the victim, she would likely now be a happily married 32-year-old with children, good finances and a successful wedding photography business.
Earlier on Tuesday, Jodi Arias told jurors she planned to use her time in prison to bring about positive changes, including donating her hair to be made into wigs for cancer victims, helping establish prison recycling programs and designing T-shirts to raise money for domestic abuse victims.
Jodi Arias became emotional as she displayed for jurors photos of her friends, boyfriends and family members, including newborn relatives she has met only from behind bars.
She asked jurors to reject the death penalty for the sake of her family.
"I'm asking you to please, please don't do that to them. I've already hurt them so badly, along with so many other people," she said.
"I want everyone's healing to begin, and I want everyone's pain to stop."
Jodi Arias stabbed and slashed Travis Alexander nearly 30 times, shot in him in the forehead and slit his throat, nearly decapitating him, before leaving his body in his shower to be found by friends about five days later.
"To this day, I can hardly believe I was capable of such violence. But I know that I was," Jodi Arias told jurors.
"And for that, I'm going to be sorry for the rest of my life."
Her speech to jurors came a day after her attorneys asked to be removed from the case, saying the five-month trial had become a witch hunt that prompted death threats against a key witness in the penalty phase. They also argued for a mistrial. The judge denied both requests.
Travis Alexander's family showed little emotion as Jodi Arias' mother, father and sister looked on from the other side of the gallery and cried.
After Jodi Arias finished speaking, Judge Sherry Stephens explained to jurors that their finding would be final
The jury heard closing arguments later on Tuesday, with Jennifer Willmott citing Jodi Arias' mental health problems and lack of a criminal record among the reasons to spare her life.
"The question now before you is: Do you kill her? Do you kill her for the one act that she did, the one horrible act, or can you see that there is a reason to let her live? Can you see that there is value in her life?" she said.
Prosecutor Juan Martinez said that despite Jodi Arias' claims, there were no factors in the case that would warrant a sentence other than death.
He implored jurors to look at the "whole panorama" of the case, not just Jodi Arias' statement on Tuesday, and explained how Travis Alexander's family will live with the pain of their loss for the rest of their lives.
"They can't forget that what happened on that afternoon, Travis Victor Alexander suffered immense physical pain," Juan Martinez said.
"They can't forget that."
[youtube VBKyaRWtqmQ]

subset: commoncrawl


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Solé Raw water pump
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* Images may differ from the actual product.


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Healthcare Industry News: St Jude
News Release - January 9, 2013
Velomedix Receives Health Canada Approval for VELOCITY Pilot Study and Bolsters Leadership Team
Approval allows Velomedix to expand VELOCITY study into Canada and accelerate enrollmentMENLO PARK, Calif.--(Healthcare Sales & Marketing Network)--Velomedix, a venture-backed medical device company advancing the field of therapeutic hypothermia, today announced it has received Health Canada Approval for its VELOCITY pilot study in addition to the previously announced US IDE approval. The study is a prospective, randomized, multi-center study designed to further evaluate the safety and feasibility of the Velomedix rapid therapeutic hypothermia system in patients with acute myocardial infarctions (AMIs or heart attacks). The study will enroll 60 awake patients with anterior ST segment elevation myocardial infarctions (STEMIs) at up to three Canadian sites in addition to US sites. Patients will be randomized to either primary percutaneous coronary intervention (PCI) or a combination of primary PCI and cooling to therapeutic temperatures before reperfusion.
"We are excited by the positive response from Health Canada," said Griff Tully, M.D., Chief Medical Officer of Velomedix. "The expansion of the VELOCITY study into Canada will provide broader physician and patient experience on the use of therapeutic hypothermia in STEMI patients. We are working with very experienced STEMI centers across Canada to obtain hospital approval and begin enrollment. Once active, we expect these sites will enroll a good percentage of the sixty patients."
The study's primary endpoint is a composite of specific new-onset, serious adverse events during the first thirty days following treatment. Several secondary endpoints will also be collected, including infarct size, myocardial salvage, left ventricular volumes, and left ventricular ejection fraction, assessed by cardiac magnetic resonance imaging (MRI). Thus, while primarily a safety trial, the study will also gather initial efficacy information.
Previous studies of therapeutic hypothermia in AMI patients have shown that cooling can significantly reduce the severity of STEMIs only if patients are cooled to temperatures of less than 35°C prior to PCI. The Velomedix approach may be unique in its ability to cool patients to this desired temperature in less than 15 minutes.
Concurrent with initiating the VELOCITY trial, Velomedix strengthened its leadership team with the addition of Vicki Bebeau as Vice President of Clinical Affairs. Ms. Bebeau has more than 18 years of experience in the planning and execution of drug and medical device trials across multiple geographies.
From 2005 to 2012, Ms. Bebeau served as Senior Clinical Director for the St Jude Medical cardiovascular and international divisions where she was responsible for several IDEs, PMAs, and post market programs supporting regulatory approvals and physician adoption in the U.S., Canada, Europe, Australia, and Japan. Prior to her tenure at St. Jude Medical, Ms. Bebeau served in various clinical leadership roles at Boston Scientific and Medtronic. Ms. Bebeau holds a BSN from Bethel College and is a licensed registered nurse.
About Acute Myocardial Infarction (AMI)
AMI affects 1,255,000 people in the US yearly1, reducing the heart's ability to pump the needed amount of blood throughout the body. The most severe form of AMI, called ST segment elevation myocardial infarction (STEMI), often leads to heart failure, a substantially debilitating disease and one of the most costly conditions for our healthcare system.
While it is extremely important to restore blood flow to the heart as early as possible, the process (called reperfusion) may cause coincidental damage, known as reperfusion injury. Thus, (it is hypothesized that) an approach that not only restores blood flow quickly, but also minimizes reperfusion injury, could further improve AMI patient outcomes and substantially reduce overall healthcare costs.
About the Velomedix mild therapeutic hypothermia system
The Velomedix mild therapeutic hypothermia system incorporates a peritoneal-based approach to rapidly cool patients from their core. Using tools and techniques similar to those for peritoneal dialysis, the physician first accesses the peritoneal cavity and then uses the Velomedix system to circulate cold fluid in the peritoneal cavity. This cavity provides a unique means of very rapidly removing heat (cooling) from the patient due to the fact that the cavity is in contact with a large part of the body's core and a high percentage of blood flows past it at any one time. This efficient "heat exchanger" enables the system to cool patients to less than 35 degrees C in fewer than 15 minutes on average.
For additional information, please visit www.velomedix.com.
Note: The Velomedix Automated Peritoneal Lavage System is limited by federal (United States) law to investigational use only and is not available for sale.
1. Véronique R. Heart Disease and Stroke Statistics--2012 Update: A Report From the American Heart Association. Circulation. 2012;125:e2-e220.
Source: Velomedix
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Please address inquiries directly to the issuing company.