To make certain actions simpler I'd like to know if it's possible to extend the node class in a way that allows you to add functions to the node class. What I mean is, I want to be able to perform actions like   $node-&gt;test();   or  $node-&gt;styledImage('field_name','style');   I was attempting to create it in a custom module like so  &lt;?php  use Drupal\node\Entity\Node as BaseNode;  class AbleNode extends BaseNode {     public function test(){         return 'test';     } }   but then it dawned on me that this probably would only create a new type of entity that could give me those functions. It wouldn't actually let me perform these actions are preexisting nodes. Is adding functions to the node class possible, or even practical?
In Drupal 8 you can load an entity with:  $node = \Drupal::entityManager()-&gt;getStorage('node')-&gt;load(123);   This looks for the entity definitions and finds that node is defined by Drupal\node\Entity\Node - so (I guess) Drupal\node\NodeStorage will instantiate a new Drupal\node\Entity\Node instance.  What I'd like to achieve is subclassing Drupal\node\Entity\Node and being able to instantiate this subclass when it's appropriate. For example if I have a node bundle article, there would be a class:  namespace Drupal\my_module\Entity\Article; class Article extends Drupal\node\Entity\Node { }   And I'd call:  $node = \Drupal::entityManager()-&gt;getStorage('node_article')-&gt;load(123);   And the return would be my Article subclass.  I can achieve this by creating a new entity type and wiring it back to another existing entity definitions, for example the node-article example would be this class:  namespace Drupal\my_module\Entity; use Drupal\node\Entity\Node; /**  * @ContentEntityType(  *   id = "node_article",  *   label = @Translation("Content"),  *   bundle_label = @Translation("Content type"),  *   handlers = {  *     "storage" = "Drupal\node\NodeStorage",  *     "storage_schema" = "Drupal\node\NodeStorageSchema",  *     "view_builder" = "Drupal\node\NodeViewBuilder",  *     "access" = "Drupal\node\NodeAccessControlHandler",  *     "views_data" = "Drupal\node\NodeViewsData",  *     "form" = {  *       "default" = "Drupal\node\NodeForm",  *       "delete" = "Drupal\node\Form\NodeDeleteForm",  *       "edit" = "Drupal\node\NodeForm"  *     },  *     "route_provider" = {  *       "html" = "Drupal\node\Entity\NodeRouteProvider",  *     },  *     "list_builder" = "Drupal\node\NodeListBuilder",  *     "translation" = "Drupal\node\NodeTranslationHandler"  *   },  *   base_table = "node",  *   data_table = "node_field_data",  *   revision_table = "node_revision",  *   revision_data_table = "node_field_revision",  *   translatable = TRUE,  *   list_cache_contexts = { "user.node_grants:view" },  *   entity_keys = {  *     "id" = "nid",  *     "revision" = "vid",  *     "bundle" = "type",  *     "label" = "title",  *     "langcode" = "langcode",  *     "uuid" = "uuid",  *     "status" = "status",  *     "uid" = "uid",  *   },  *   bundle_entity_type = "node_type",  *   field_ui_base_route = "entity.node_type.edit_form",  *   common_reference_target = TRUE,  *   permission_granularity = "bundle",  *   links = {  *     "canonical" = "/node/{node}",  *     "delete-form" = "/node/{node}/delete",  *     "edit-form" = "/node/{node}/edit",  *     "version-history" = "/node/{node}/revisions",  *     "revision" = "/node/{node}/revisions/{node_revision}/view",  *   }  * )  */ class Article extends Node { }  // Results my Article sub type. $node = \Drupal::entityManager()-&gt;getStorage('node_article')-&gt;load(123);   This works fine (as much as I can see); however, it smells. It adds a new entity type, which is not true, and might cause other troubles in the future.  How do I define a subclass for an entity bundle so that loading the entity would return an object of that class?
How fast would someone have to run to run over water? I was thinking about Flash, the superhero, or the little boy in the Incredibles.   There is  that doesn't answer a lot. Especially, I don't think surface tension would help a lot for a human to run over water, I think one would have to build on the inertial effect of the water.  There is one empirical approach based on figuring out the speed at which bare-footed water skiing is done, but I wasn't able to find a decent number. Still the difference may be that a hypothetical runner would have to propulse herself over the water, which may or may not make the thing more difficult.  Hence, I raise the question here. There were so many discussions about an Ubuntu with RR. They were so many pros and contras. At the end ubuntu wont be changed, the 6 month cycle system wont be changed. Thats fine!   But because there are so many people who would like to use an ubuntu with RR Im asking myself why isnt there an Ubuntu Derivate with RR. I couldnt found one, there are a loooot of Ubuntu Derivates but no RR. Is it just impossible? I mean Ubuntu = 6 months cycle, so the derivate have to be a 6 month cycle too? Is there no other option? Or are there already some smart guys trying to solve this problem? Thank you! Cardinality of separable metric spaces How to find an end point of an arc given another end point, radius, and arc direction? Given an arbitrary arc, where you know the following values: end point (x1,y1), radius (r) and arc direction (e.g. clockwise or counterclockwise from start to end), how can I calculate the other endpoint of the arc (and I say endpoint because I think of an arc as line segment that is curved, which happens to lie on the circumference of the circle and it has two end points).   Though that's just how I interpret the problem and maybe I'm not thinking about it correctly.  EDIT: Yes, I know the Origin point and the length of the arc. Sorry I forgot to mention. Also, the that circle would be on a 2D Cartesian plain (x and y axis.) Sorry, my math terminology is lacking.   Also, I'm not trying to cheat on homework or anything. This is a legitimate problem for an SVG graph I'm trying to create using JavaScript and I've tried my best but I need help.  Thanks in advance. How can I further diagnose my central air conditioning compressor fan motor and capacitor? I have a 15 year old Bryant Central Air unit in my house.  Yesterday it stopped working.  Here is what I have checked.   The breaker in the basement is not tripped. The furnace works fine from the thermostat. The blower downstairs by the furnace runs when AC is on and blows room temp air into the house, but the fan on the compressor is not spinning.  The fan on the compressor does spin freely when I manually spin it with a stick.  Checked for fuses in the outside box.  There are no fuses outside, only an on/off pull thingy with two metal plates that you have to turn upside down to turn off. The capacitor is not flat on top, but far less rounded then any of the examples of blown AC dual capacitors I've seen on youtube. I get 220v in on the contactor. I get 220v out on the contactor. I get 24v from the thermostat. When the air is on at the thermostat the contactor solenoid is in, when the air is off it is out.   When the air is on at the thermostat I hear a buzz coming from the outside compressor but I can't tell what the source of the buzz is. If I push the solenoid in when the AC is off, the compressor does not start up and the fan does not spin, I just hear the buzz. If I wait by the compressor outside for a few seconds while the AC is on there's another buzz sound that goes off for about 3 seconds then stops.  From listening to the AC when it was working this is the buzz sound that goes off before the compressor and fan usually kick in. After leaving the non-functioning unit on for a few minutes while I diagnosed I noticed that the metal on top of the compressor fan motor was VERY hot to the touch.  It cooled after I turned the AC off.   I'm thinking the fan motor on the compressor is dead or the capacitor is bad.  Is there a way to check the capacitor and the fan motor while they're still in the unit?  With the power off of course.  Does anyone think it's something else?  Do I have to buy the overpriced ($485 for the manufacturer fan motor and $200 for the dual capacitor) replacement part from the manufacturer or can I use a third party manufacturer?  Any other help would be appreciated.  As much as I'd love to bring an HVAC guy in here I just can't afford it.  Either I go without AC, or I fix it myself.  EDIT:  With the AC on I manually spun up the fan on the compressor and the fan started spinning and the AC unit fired up. The extension of smooth function Uncaught ReferenceError: $ is not defined? I have a code that prints a table with 2 rows. I want to keep format of it and change 2 rows into 3.   \documentclass[conference]{IEEEtran}  \usepackage{pgfplots} \usepackage{siunitx} \usepackage{multirow} \begin{document}  \begin{table}[h] \caption{Family data set results} \label{tbl::Fam} \centering \begin{tabular}{|l|l|c|c|c!{\vrule width 2pt}l|l|c|c|c|} %\noalign{\hrule height 2pt} \hline \textbf{Column}&amp;\textbf{Algorithm}&amp;\textbf{min}&amp;\textbf{max}&amp;\textbf{std}l&amp;\textbf{Column}&amp;\textbf{Algorithm}&amp;\textbf{min}&amp;\textbf{max}&amp;\textbf{std}\\\hline \multirow{2}{*}{age}&amp;Original&amp;9&amp;2.8&amp;100&amp;\multirow{2}{*}{employer\_type}&amp;Original&amp;13&amp;2&amp;10\\ \cline{2-5} \cline{7-10}&amp;PrivBayes&amp;2&amp;95&amp;96&amp;&amp;PrivBayes&amp;2&amp;100&amp;100\\\hline \multirow{2}{*}{education\_level}&amp;Original&amp;7&amp;2&amp;98&amp;\multirow{2}{*}{marital\_status}&amp;Original&amp;10&amp;2&amp;100\\ \cline{2-5} \cline{7-10}&amp;PrivBayes&amp;2&amp;6&amp;96&amp;&amp;PrivBayes&amp;2&amp;6&amp;100\\\hline \hline %\noalign{\hrule height 2pt} \end{tabular} \end{table}  \end{document}   In this picture, I have 2 algorithms {Original, PrivBayes}. I want to change 2 algorithms into 3 algorithms with keeping the format of table. Can you please help me to do it? Viewer-independent copyable spaces at the beginning of a line? I need to include a couple of Python code listings, where the indentation of the lines (using some number of spaces) is significant. I would like for the code listings to be copyable, so the spaces at the beginning of the line need to be be copied along with the text.  This question has been asked in various ways before (e.g. , or ). Those questions focus on making line numbers uncopyable, though.  Making the spaces at the beginning of a line copyable seems to be harder: "I am not sure it is possible to specify in the PDF (at least in a viewer-independent way) that the indentation should be copied too" (). At , Philippe Goutet suggests a solution (turning the spaces into visible spaces, and coloring them in the background color so that they appear invisible) that works using Acrobat Reader, but not all readers. He says "It works under Acrobat Reader and it's extremely pleasant to be able to quickly copy/paste code without problem (perhaps the problem can be circumvented by writing direct PDF code to tell that it's a space, I've never had the time to try)".  Is it possible to produce a PDF with a code listing with copyable real spaces at the beginning of a line?  Minimal example: The line return x should start with four spaces.  \documentclass{article}  \begin{document} \begin{verbatim} def myfunction(x):     return x \end{verbatim} \end{document}   I know that I could attach the code to the PDF as a file, but that's not what I want. Rectifiability of a curve Let $f$ be a function defined on $[0,1]$ by   $$f(x) = { 0, \text{ if } x = 0} $$ $$f(x) = { x \sin \frac 1 x , \text{ if } 0 &lt; x \leq 1} $$  Prove that the curve $\{(x, f(x)) : x \in [0,1]\}$ is not rectifiable.   I'm not sure how to approach this. The general idea seems logical, we're proving that the length of the curve is infinite, but the method seems difficult to find. Here $n$ belongs to natural numbers. Firstly, I proved the relation by putting $n = 1$ . Then, taking $$|\sin(mx)| \leq m|\sin x|$$ true, I had to prove $$|\sin(m + 1)x| \leq (m + 1)|\sin x|$$  Now, here I got stuck. How to prove it?? Please help. Are Complex Substitutions Legal in Integration? This question has been irritating me for awhile so I thought I'd ask here.  Are complex substitutions in integration okay?  Can the following substitution used to evaluate the Fresnel integrals:  $$\int_{0}^{\infty} \sin x^2\, dx=\operatorname {Im}\left( \int_0^\infty\cos x^2\, dx + i\int_0^\infty\sin x^2\, dx\right)=\operatorname {Im}\left(\int_0^\infty \exp(ix^2)\, dx\right)$$  Letting $ix^2=-z^2 \implies x=\pm\sqrt{iz^2}=\pm \sqrt{i}z \implies z=\pm \sqrt{-i} x \implies dx = \pm\sqrt{i}\, dz$  Thus the integral becomes  $$\operatorname {Im}\left(\pm \sqrt{i}\int_0^{\pm\sqrt{-i}\infty} \exp(z^2)\, dz\right)$$  This step requires some justification, and I am hoping someone can help me justify this step as well: $$\pm \sqrt{i}\int_0^{\pm\sqrt{-i}\infty} \exp(z^2)\, dz=\pm\sqrt{i}\int^\infty_0\exp(z^2)\, dz=\pm\sqrt{i}\left(\frac{\sqrt{\pi}}{2}\right)$$  Thus  $$\operatorname {Im}\left(\int_0^\infty \exp(ix^2)\, dx\right)=\operatorname {Im}\left(\pm\frac{\sqrt{i\pi}}{2}\right)=\operatorname {Im}\left(\pm\frac{(1+i)\sqrt{\pi}}{2\sqrt{2}}\right)=\pm\frac{1}{2}\sqrt{\frac{\pi}{2}}$$  We find that the correct answer is the positive part (simply prove the integral is positive, perhaps by showing the integral can be written as an alternating sum of integrals).  Can someone help justify this substitution?  Is this legal? Motivation: I once had one surplus card on my hand, and knew the robbers would come soon. So I gave it to someone for free, to avoid losing more cards when they hit. I was surprised by how badly this was received. Two of the three other players (the hosts of the game) acted upset, like I had tried to cheat. I had to take the card back, get robbed the next turn and 'giving cards away for free' was banned immediately. (Oh, how I hate mid-game additions to the rules. But that's beside the point.)  So now the question: Is this really illegal in Settlers of Catan? Is it generally considered underhanded in any way? If so, why?   My reasoning was like this:        Consider players A and B.   A wants to give B a sheep.   A trades a sheep and one rock to B, in exchange for wheat.   A trades the received wheat for the (formerly his) rock.   A and B now both have the same resources they had in the beginning, only the sheep has moved from A to B. Is it possible to have a 100% secure virtual private server? Create directory if it does not exist Are all eigenvectors, of any matrix, always orthogonal? In a LaTeX article, the math characters are more "curvy" than the text characters:  \documentclass[12pt]{article} \begin{document}  $x^2 + y^2 = z^2$ \end{document}     In a beamer presentation, the math characters do not have the same curves:  \documentclass{beamer} \begin{document} \begin{frame}  $x^2 + y^2 = z^2$ \end{frame} \end{document}     Question  How can I get the beamer math to look just like the article math?  I would prefer if the solution was a single line (that I could place at the top of my LaTeX file) as opposed to something that needs to appear next to every piece of math. I normally dual-boot with 12.04 and Win XP pro sp3 on a Thinkpad R60.  I needed to reinstall windows because of problems piling up, so I ran the computer's built-in hard-disk recovery software.  I told it not to mess with the other partitions, but somehow it deleted the Linux partition.  That's what I was using to backup all of my windows files, so now everything I have is gone.  I just ran the USB setup with linux, and the partition is deleted - it just shows it as empty space.    Is there ANY way to get all of my files back? Mongoose Sub Document Woes How can I stop Ubuntu Dock from extending to the edges? By default Ubuntu Dock in Ubuntu 17.10 and later releases always extends to the edges (top-bar-to-bottom if placed on the left or right and left-to-right when placed at the bottom) even when it's not filled with icons. Is there a way to prevent this behaviour (i.e. I want to make the dock-length flexible so that as the number of application icons in the dock increases, it should expand accordingly)?  ➡️➡️➡️  In other words, is there a way make Ubuntu Dock look like a &quot;proper dock&quot; instead of a side/bottom panel with full-height/width?