Does it refer to the object the handler it is defined in or the object than handle belongs to:  example:  class foo   {  Object a;  public foo()  {   a.handle += function;      }   void function()  {        this;&lt;--What does this "this" refer to foo or object a?  }     }
I was curious about how other people use the this keyword. I tend to use it in constructors, but I may also use it throughout the class in other methods. Some examples:  In a constructor:  public Light(Vector v) {     this.dir = new Vector(v); }   Elsewhere  public void SomeMethod() {     Vector vec = new Vector();     double d = (vec * vec) - (this.radius * this.radius); }
Is it possible for information (like 1 and 0s) to be transmitted faster than light?   For instance, take a rigid pole of several AU in length. Now say you have a person on each end, and one of them starts pulling and pushing on his/her end.   The person on the opposite end should receive the pushes and pulls instantaneously as no particle is making the full journey.  Would this actually work? If a function $f$ defined on $[a,b]$ and differentiable everywhere, does it mean that its derivative $f'(x)$ is continuous everywhere on $[a,b]$?  My understanding is 'yes'. Because if there were 'a gap' in $f'(x)$, we could integrate back to $f(x)$ and show that where the gap is, there would be a sharp "angle" where $f(x)$ is not differentiable. Well, you can see it for yourself. The badge multiplier is a bit misaligned. Can you fix this please? (I know it's kinda a minor issue but it's bugging me and it's somehow off)    If it helps, I'm using Chrome version 44.0.2403.125 m. (Also repro'ed on FireFox 39.0 and )    For no good reason, that's a screenie from 's profile page. How Do I get into the castle walls? I already have the pink and red leather gloves, the armor, the crown, and the monkey's staff (and they're all enchanted). Regardless of how many health potions I use, I always die. Help! Geoserver ecw plugin problem I am trying to publish some ecw files with geoserver 2.7.2 on ubuntu 15.04 x64. I downloaded gdal plugin, gdal_data and native libraries for image-io 1.1.11 and set environment variables; GDAL_DATA, LD_LIBRARY_PATH.  I can see new store types when adding new one (ECW, EHdr, JP2ECW etc.). But when I try to save an ECW store with a valid ecw file which I tested with ArcMap, geoserver crashes with this error:    terminate called after throwing an instance of 'std::length_error'   what():  basic_string::_S_create Aborted (core dumped)  Do you have any idea about this problem? Please help me to find elements $a,b$ in a ring $R$ such that $a\mid b$ and $b\mid a$, but there does not exist any unit $u$ in $R$ such that $a=ub$. I am trying to make a callout to AWS S3 using named credentials and Apex  The named credential is set up as follows  Label: AWS S3 Name: AWS_S3 URL: https://bucket-name.s3.amazonaws.com - Certificate: Identity Type: Named Principal Authentication Protocol: AWS Signature Version 4 AWS Access Key: AKIAxxxxxx AWS Secret Access Key: xxxxxx AWS Region: ap-southeast-2 AWS Service: s3 - Generate Authorization header: true Merge fields in header: false Merge fields in body: false   The Apex class is very simple  HttpRequest req = new HttpRequest(); req.setEndpoint('callout:AWS_S3'); req.setMethod('GET');                        Http http = new Http(); HTTPResponse res = http.send(req);                 System.debug(res.getBody()); return res.getBody();   The response body contains the following:     SignatureDoesNotMatchThe request signature we calculated does not match the signature you provided. Check your key and signing method.AKIAxxxxx   I have used the same bucket, endpoint and credentials using Postman and am able to successfully return the list of objects in the bucket so it is not an IAM permissions issue  There have been a couple of similar questions on stackexchange but unfortunately they do not provide any resolution or assistance in this case:    I've tried looking for code samples or further pointers in the Apex documentation but it doesn't really give any further guidance on how to proceed or correctly set this up so I'm a bit stuck How do I copy a file in Python?  I couldn't find anything under . Turning live() into on() in jQuery Create database fields to an existing table when installing a module I'm new to drupal and I need some help.  I created a new module with name user_extra. Which create necessery table when Installing the module.  But I also need to insert some database field in 'users_field_data' table ('user_extra_id' and 'user_office')  In baseFieldDefinitions I wrote all necessery database table fields for user_extra table.   public static function baseFieldDefinitions(EntityTypeInterface $entity_type) {     // Standard field, used as a unique if primary index.     $fields['id'] = BaseFieldDefinition::create('integer')         -&gt;setLabel(t('Unit ID'))         -&gt;setDescription(t('The unit ID.'))         -&gt;setReadOnly(TRUE)         -&gt;setSetting('unsigned', TRUE);      $fields['uuid'] = BaseFieldDefinition::create('uuid')         -&gt;setLabel(t('UUID'))         -&gt;setDescription(t('The unit UUID.'))         -&gt;setReadOnly(TRUE);         .         .         .     $fields['user_info'] = BaseFieldDefinition::create('string')         -&gt;setLabel(t('User Info'))         -&gt;setDescription(t("The User Info"))         -&gt;setSetting('max_length', 255)         -&gt;setDisplayOptions('form', array(           'type' =&gt; 'string_textfield',           'weight' =&gt; 10,         ))         -&gt;setDisplayConfigurable('form', TRUE);      return $fields;      }   When I install the module it inserts all values that I define in baseFieldDefinitions.  But I also need to create 'user_extra_id' and 'user_office' in 'users_field_data' table with setDisplayOptions and setDisplayConfigurable options.  This is the commenting that I made in entity file  /**  * @ContentEntityType(  *   id = "user_extra",  *   label = @Translation("user extra"),  *   handlers = {  *     "storage" = "Drupal\user_extra\UserextraStorage",  *     "storage_schema" = "Drupal\user_extra\UserextraStorageSchema",  *     "access" = "Drupal\user_extra\UserextraAccessControlHandler",  *     "list_builder" = "Drupal\user_extra\UserextraListBuilder",  *     "view_builder" = "Drupal\user_extra\UserextraViewBuilder",  *     "views_data" = "Drupal\user_extra\UserextraViewsData",  *     "form" = {  *       "default" = "Drupal\user_extra\Form\UserextraForm",  *       "add" = "Drupal\user_extra\Form\UserextraAddForm",  *       "edit" = "Drupal\user_extra\Form\UserextraEditForm",  *       "delete" = "Drupal\user_extra\Form\UserextraDeleteForm",  *     }  *   },  *   admin_permission = "administer user_extra",  *   base_table = "user_extra",  *   entity_keys = {  *     "id" = "id",  *     "label" = "name",  *     "uuid" = "uuid",  *   },  *   links = {  *     "canonical" = "/admin/user_extra/{user_extra}",  *     "add-form" = "/admin/user_extra/add",  *     "delete-form" = "/admin/user_extra/{user_extra}/delete",  *     "overview-form" = "/admin/user_extra/${user_extra}/overview",  *     "edit-form" = "/admin/user_extra/{user_extra}",  *     "collection" = "/admin/user_extra",  *     "children" = "/admin/user_extra/{user_extra}/children",  *   },  * )  */ Spaces and em-dash In using the em-dash, where do you put the spaces? Which of the following is correct?     School is based on the three R’s —reading, writing, and ’rithemtic.   or     School is based on the three R’s— reading, writing, and ’rithemtic.   or     School is based on the three R’s — reading, writing, and ’rithemtic. I'm applying for B1/B2 visa. In DS-160, it asks for      Monthly Salary in Local Currency (if employed)   However it doesn't mention anywhere if this should be gross (before tax deductions) or net (after tax deductions, whatever is credited into my account every month).  What should I fill here? Prove that :  $$ \frac{\sqrt{\pi}}{2} e^{-\frac{a^2}{4} } =\int_0^{\infty} e^{-x^2} \cos( a x) \ \mathrm{d}x$$    the only thing I can think of is differentiating the RHS and trying to get :  $$ -2 f'(a) =a f(a) $$ But I couldn't do it.  Can anyone show me how to do this ? Why doesn't running "sudo shutdown now" shut down? Is there a systematic way to obtain all conserved quantities of a system? How do I do this? I created a user without a home directory and now I want to create one. Not just a folder called new_user, I want the default home directory with all it's folders and hidden files, etc. I remember my English teacher saying that there are only two valid ways to make a one-word sentence:   A question:      Why? Where?  A command:     Go! Stop!    Is this correct? What's the frequency of filesystem check on boot? What is the maximum number of times the root filesystem on this computer can be mounted before it is automatically checked? How can we define convexity in one dimension? Definition of a convex set: A set $S\subset\mathbb R^n$ is said to be convex if for each $x_1, x_2\in S$ the line segment $\lambda x_1 + (1-\lambda)x_2$ for $\lambda\in (0,1)$ belongs to $S$. This says that all points on the line connecting two points in the set are in the set. My question is: how can we define convexity in one dimension? 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