I'm dumb and this is embarrassing, but I'm trying to figure out how I properly use a method from a class in other parts of my code. I need to understand the Drupal way, if not just the php way. I have a class like this... namespace Drupal\module_name\Utilities;  use GuzzleHttp\Exception\RequestException; use Drupal\Core\Logger\LoggerChannelFactory; use Drupal\Core\Messenger\MessengerInterface; use Symfony\Component\DependencyInjection\ContainerInterface; use GuzzleHttp\ClientInterface; use Drupal\Core\Config\ConfigFactoryInterface; use Drupal\Core\DependencyInjection\ContainerInjectionInterface;  class Example implements ContainerInjectionInterface {    private $client;   protected $loggerFactory;   protected $messenger;   protected $config;    public function __construct(     LoggerChannelFactory $loggerFactory,     MessengerInterface $messenger,     ClientInterface $client,     ConfigFactoryInterface $config   ) {     $this-&gt;loggerFactory = $loggerFactory-&gt;get('simple_mailchimp');     $this-&gt;messenger = $messenger;     $this-&gt;client = $client;     $this-&gt;config = $config-&gt;get('module_name.settings');   }    public static function create(ContainerInterface $container) {     return new static(       $container-&gt;get('logger.factory'),       $container-&gt;get('messenger'),       $container-&gt;get('http_client'),       $container-&gt;get('config.factory')     );   }    public function request() {     return 'whatever';   } }  What's the proper way to use this class somewhere else? For instance, in another module, I want to call the request() method shown above.   $example = new Example();   $x = $example-&gt;request();  This doesn't work, as shown above. I get this... ArgumentCountError: Too few arguments to function Drupal\module_name\Utilities\Example::__construct(), 0 passed... and exactly 4 expected  (Even though it seemed to have worked at one time.) That said, what's the right way to go about this with Drupal, or in general, I guess?
I am relatively fresh to the DI party and am struggling to get my head around how exactly to use Dependency Injection. I understand that I can pass requirements as part of a service, but what about in my own class?  Say I have the below class where I want the language manager service to be injected:  class Foo implements ContainerInjectionInterface {    protected $languageManager;     public function __construct(LanguageManagerInterface $languageManager) {     $this-&gt;languageManager = $languageManager;   }    public static function create(ContainerInterface $container) {     return new static(       $container-&gt;get('language_manager')     );   } }   When I call new Foo() I am required to pass an instance of LanguageManagerInterface. That makes sense in terms of a normal constructor method, but that would require me to instantiate the class like the below:  $languageManager = \Drupal::service('language_manager'); $foo = new Foo($languageManager)   That just doesn't feel right to me.  Is there something I am missing, or would this class always have to be a service to take advantage of dependency injection?
I know that it is defined such that there is no more than one y-value output for any given x-value input, but I"m wondering WHY it is defined that way? Why can't we apply everything we know about functions to equations that have more than one y-value output for any given x-value input?   In short, what is the benefit or reason to define a function this way?  At the same time, a little historical context would also be appreciated (i.e., when the concept originated and why).  Thanks,  Moshe $(K[x,y,z]/(x^2+y^3+z^7))_{(x,y,z)}$ is a UFD. Is there a good reason for the removal of this FrameTicks syntax? How to generate a random number between 1 and 10 with a six-sided die? I know it existed as sort of a folder in Windows Explorer in at least Windows XP, but I just can't seem to find it in Windows 7...  How can I take a picture with my webcam in Windows 7 without using any 3rd party tools? Is there an unsubdivide function in Blender? Prove that $\binom{m+n}{m}=\sum\limits_{i=0}^m \binom{m}{i}\binom{n}{i}$ I'm using the word "Zwei-Drittel-Abstimmungsmehrheit" a bunch of times in my document. Often it won't fit into the current line, extending into the right margin.  I figured out that the following package helps :  \usepackage[shortcuts]{extdash}    Then I can write  Zwei\-/-Drittel\-/Abstimmungs\-mehrheit   and the hyphenation is done correctly.  Is there a way that I can set this hyphenation globally for this word? Like i can do it with the command  \hyphenation{...}   Sadly this command doesn't work for words containing dashes. Typesetting a function defined by case analysis Can any one suggess me the code to write this equation in LaTeX. Are the XBLA and PC versions of Minecraft compatible? There exists an injection from $X$ to $Y$ if and only if there exists a surjection from $Y$ to $X$. Theorem. Let $X$ and $Y$ be sets with $X$ nonempty. Then (P) there exists an injection $f:X\rightarrow Y$ if and only if (Q) there exists a surjection $g:Y\rightarrow X$.  For the P $\implies$ Q part, I know you can get a surjection $Y\to X$ by mapping $y$ to $x$ if $y=f(x)$ for some $x\in X$ and mapping $y$ to some arbitrary $\alpha\in X$ if $y\in Y\setminus f(X)$. But I don't know about the Q $\implies$ P part.  Could someone give an elementary proof of the theorem? Question mark or period to end a rhetorical sentence Which makes more sense as end punctuation for the following rhetorical sentence—a period or a question mark?     Maybe you could be a security guard there and enforce whatever the WalMart policy is at that location Negative R squared contradicts ssa/sst? I understand from this question -    that the R squared value of a linear regression model can be negative if the intercept is constrained. And this makes sense if you define R squared as -   $$R^2 = 1-\frac{SSE}{SST}$$  One says $SSE&gt;SST$. But then,  $$SST = SSA + SSE $$ Total Sum of squares  = Sum of squared errors + Sum of squared residual. And with this we get -  $$R^2 = \frac{SSA}{SST}$$ And now it is hard to imagine how $R^2$ can be negative. Aren't SSA and SST >0 always? Let $G$ be a finite group. For each positive integer $m$, if $x^{m}=e$ has at most $m$ solutions in $G$, $G$ is cyclic.   What I have thought is that $n=\sum_{d\mid n}\phi(d)$ can be used to solve this and showing that $|G|$ order element in $G$ exists is enough. Creating the Nabla operator (also known as Del operator) as an operator Basic mathematical induction regarding inequalities These are just the examples from my textbook, but I don't think it did not explain well.  One of the problem was to prove the inequality   $$n&lt;2^n$$  for all integers $n$.  I understand we assume if $P(n)$ is true, $P(k+1)$ is true.  Thus $k+1&lt; 2^{k+1}$  But in the text book, they added one more line that I don't understand:  $$k+1&lt;2^k+1 \le 2^k+2^k=2\cdot2^k=2^{k+1}$$  I understand  $$k+1&lt;2^{k+1}$$  But how do I know $2^k+1$ is larger than $k+1$, and smaller than $2^{k+1}$?  I have one another example just in case,  proving $2^n&lt;n!$ using induction.  $$2^{k+1}=2\cdot 2^k&lt;2\cdot k!&lt;(k+1)k!=(k+1)!$$  I understand we should start with $2^{k+1}&lt;(k+1)!$, but  Where did $2\cdot k!$ come from? Textbook says it came from inductive hypothesis, but I still don't get it.  Please advise. Making a HUD/GUI with OpenGL (LWJGL) So I know umask can restrict privileged users, using this format umask ugo.  I understand that the read = 4, write = 2, and exec = 1. However, when I type umask, it returns 4 digits which is 0022 or 0073. I have no understanding of how does this work now because there is an extra digit. What is that extra digit and what does 0022 mean? How to only perform LTS upgrades? Time Expressions with "in" I have seen some examples about using "in" with time expressions. They give some examples as shown below:     I will leave for vacation in a month. (Exactly one month from now I   will go on vacation.)      We’ll be there in an hour.  (Exactly one hour will go by and then we   will arrive.)   But these comments confused me. Then I looked the usage of "in" up in a dictionary and it says about usage of "in" with time expressions :"before or at the end of a particular period". I think the comments and the definition in the dictionary contradict each other?    I have examples of mine:     1- Dinner will be ready in ten minutes. (Maybe dinner will be   ready at the 5th minute? or 8th. Does it strictly mean dinner will be   ready at the end of the ten minutes?)      2- My letter arrived in two days. ( Does that mean it took   exactly two days to arrive? or Could it be just one day because he/she   doesnt remember the exact time?)      3- Imagine you are on the first day of a month and your friend says:   I will be going outside the country in this month. (Does that mean he/she could go tomorrow or ten days later or at the end of the   month?)      4- He can run a mile in 5 minutes. ( Does that mean he has to   spent entire 5 minutes to run a mile? Could it be 4 or 4.5 minutes?)