Try:

    $this-&gt;{$this-&gt;data[&#39;action&#39;]}();

You can do it safely by checking if it is callable first:

    $action = $this-&gt;data[&#39;action&#39;];
    if(is_callable(array($this, $action))){
    	$this-&gt;$action();
    }else{
        $this-&gt;default(); //or some kind of error message
    }

Reemphasizing what the OP mentioned, [`call_user_func()`][cuf] and [`call_user_func_array()`][cufa] are also good options.  In particular, `call_user_func_array()` does a better job at passing parameters when the list of parameters might be different for each function.

    call_user_func_array(
        array($this, $this-&gt;data[&#39;action&#39;]),
        $params
    );

[cuf]: http://www.php.net/manual/en/function.call-user-func.php
[cufa]: http://www.php.net/manual/en/function.call-user-func-array.php

Simple, probably dumb question: Suppose I have a Java server that stores in memory commonly used keys and values which I can query (let&#39;s say in a HashMap)

What&#39;s the difference between that and using Memcache (or even Redis)? They both store things in memory. Is there a benefit to one or the other? Does Memcache leaves less of a memory footprint? Can store more in less memory? Faster to query? No difference?

Memcache vs Java Memory

I&#39;m doing a `UNION` of two queries on an Oracle database. Both of them have a `WHERE` clause. Is there a difference in the performance if I do the `WHERE` after `UNION`ing the queries compared to performing the `UNION` after `WHERE` clause?

For example:

    SELECT colA, colB FROM tableA WHERE colA &gt; 1
    UNION
    SELECT colA, colB FROM tableB WHERE colA &gt; 1

compared to:

    SELECT * 
      FROM (SELECT colA, colB FROM tableA
            UNION
            SELECT colA, colB FROM tableB) 
     WHERE colA &gt; 1

I believe in the second case, it performs a full table scan on both the tables affecting the performance. Is that correct?

UNION with WHERE clause

    Class MyClass{
      private $data=array(&#39;action&#39;=&gt;&#39;insert&#39;);
      public function insert(){
        echo &#39;called insert&#39;;
      }
    
      public function run(){
        $this-&gt;$this-&gt;data[&#39;action&#39;]();
      }
    }

This doens&#39;t work:

    $this-&gt;$this-&gt;data[&#39;action&#39;]();

only possibilites is to use `call_user_func();` ?

Call method by string?

<pre><code class="hljs language-php">Class MyClass{
 private $data=array('action'=>'insert');
 public function insert(){
 echo 'called insert';
 }

 public function run(){
 $this->$this->data['action']();
 }
}
</code></pre>
This doens't work:
<pre><code class="hljs language-kotlin">$this->$this->data['action']();
</code></pre>
only possibilites is to use <code>call_user_func();</code> ?

I have the following script which is good IMO for returning many rows from the database because of the &quot;foreach&quot; section.

How do I optimize this, if I know I will always only get 1 row from the database.  If I know I will only ever get 1 row from the database, I don&#39;t see why I need the foreach loop, but I don&#39;t know how to change the code.

    $STH = $DBH -&gt; prepare( &quot;select figure from table1&quot; );
    $STH -&gt; execute();
    $result = $STH -&gt; fetchAll();
    foreach( $result as $row ) {
    	echo $row[&quot;figure&quot;];
    }


PHP PDO returning single row

How can I generate a 6 digit unique number? I have verification mechanisms in place to check for duplicate entries.  

How can I generate a 6 digit unique number?

How can I search and find, for a given target value, the closest value in an array?

Let&#39;s say I have this exemplary array:

    array(0, 5, 10, 11, 12, 20)


For example, when I search with the target value 0, the function shall return 0; when I search with 3, it shall return 5; when I search with 14, it shall return 12.

Find a matching or closest value in an array

I have an array: 

    [13] =&gt; Array
            (
                [0] =&gt; joe
                [1] =&gt; 0
            
        [14] =&gt; Array
            (
                [0] =&gt; bob
                [1] =&gt; 0
            )
    
        [15] =&gt; Array
            (
                [0] =&gt; sue
                [1] =&gt; 0
            )
    
        [16] =&gt; Array
            (
                [0] =&gt; john
                [1] =&gt; 0
            )
    
        [17] =&gt; Array
            (
                [0] =&gt; harry
                [1] =&gt; 0
            )
    
        [18] =&gt; Array
            (
                [0] =&gt; larry
                [1] =&gt; 0
            )

How can I get the last 3 elements while preserving the keys? (the number of elements in the array may vary, so I cannot simply slice after the 2nd element)

So the output would be:

      [16] =&gt; Array
            (
                [0] =&gt; john
                [1] =&gt; 0
            )
    
        [17] =&gt; Array
            (
                [0] =&gt; harry
                [1] =&gt; 0
            )
    
        [18] =&gt; Array
            (
                [0] =&gt; larry
                [1] =&gt; 0
            )




PHP get the last 3 elements of an associative array while preserving the keys?

I would like to compare two variables to see if they are the same, but I want this comparison to be case-insensitive.

For example, this would be case sensitive:

    if($var1 == $var2){
       ...
    }

But I want this to be case insensitive, how would I approach this?

Case insensitive string comparison

In a Java class a method can be defined to be `final`, to mark that this method may not be overridden:

    public class Thingy {
        public Thingy() { ... }
        public int operationA() {...}
        /** this method does @return That and is final. */
        public final int getThat() { ...}
    }

That&#39;s clear, and it may be of some use to protect against accidental overriding, or maybe performance &amp;mdash; but that&#39;s not my question.

My question is: From an OOP point of view I understood that, by defining a method `final` the class designer *promises* this method will always work as described, or implied. But often this may be outside the influence of the class author, if what the method is doing is more complicated then just delivering a *property*.

The syntactic constraint is clear to me, but what is the implication in the OOP sense? Is `final` used correctly in this sense by most class authors?

**What kind of &quot;contract&quot; does a `final` method promise?**

Java `final` method: what does it promise?

Declaring a variable in a class (outside of a function): all class functions can access it (basically a public variable)

Declaring a variable inside a function inside a class: only that function can access it (it&#39;s in that function&#39;s scope)

Declaring a variable with `self.(variable name)` inside a function inside a class: all class functions can access it (how is this different from `global (variable name)`?)

And since there is no private/protected, everything is public, so everything accessible from inside a class is accessible from outside the class.

Are there any other nuances I should know, or have I pretty much got it?

Variable scopes in Python classes

In Domain Driven Design, there seems to be [lots][1] of [agreement][2] that Entities should not access Repositories directly. 

Did this come from Eric Evans [Domain Driven Design][3] book, or did it come from elsewhere?
 
Where are there some good explanations for the reasoning behind it?
  
edit: To clarify: I&#39;m not talking about the classic OO practice of separating data access off into a separate layer from the business logic - I&#39;m talking about the specific arrangement whereby in DDD, Entities are not supposed to talk to the data access layer at all (i.e. they are not supposed to hold references to Repository objects)

update: I gave the bounty to BacceSR because his answer seemed closest, but I&#39;m still pretty in the dark about this. If its such an important principle, there should be some good articles about it online somewhere, surely?

update: March 2013, the upvotes on the question imply there&#39;s a lot of interest in this, and even though there&#39;s been lots of answers, I still think there&#39;s room for more if people have ideas about this.

  [1]: http://thinkddd.com/blog/2009/03/02/the-specification-pattern/
  [2]: https://stackoverflow.com/questions/827670/is-it-ok-for-entities-to-access-repositories/827693#827693
  [3]: http://www.amazon.co.uk/Domain-driven-Design-Tackling-Complexity-Software/dp/0321125215

DDD - the rule that Entities can&#39;t access Repositories directly

I have a number `Processor` classes that will do two very different things, but are called from common code (an &quot;inversion of control&quot; situation).

I&#39;m wondering what design considerations I should be cognicent (or cognizant, for you USsers) of when deciding if they should all inherit from `BaseProcessor`, or implement `IProcessor` as an interface.

When should I choose inheritance over an interface when designing C# class libraries?

I am just getting a grasp on the MVC framework and I often wonder how much code should go in the model. I tend to have a data access class that has methods like this:

    public function CheckUsername($connection, $username)
    {
        try
        {
            $data = array();
            $data[&#39;Username&#39;] = $username;

            //// SQL
            $sql = &quot;SELECT Username FROM&quot; . $this-&gt;usersTableName . &quot; WHERE Username = :Username&quot;;

            //// Execute statement
            return $this-&gt;ExecuteObject($connection, $sql, $data);
        }
        catch(Exception $e)
        {
            throw $e;
        }
    }

My models tend to be an entity class that is mapped to the database table.

Should the model object have all the database mapped properties as well as the code above or is it OK to separate that code out that actually does the database work?

Will I end up having four layers?


Content Type	Original Author	Original Content on Stackoverflow
Question	dynamic	View Question on Stackoverflow
Solution 1 - Php	Mārtiņš Briedis	View Answer on Stackoverflow
Solution 2 - Php	Brad Koch	View Answer on Stackoverflow

Call method by string?

Php Problem Overview

Php Solutions

Solution 1 - Php

Solution 2 - Php

UNION with WHERE clause

Memcache vs Java Memory

Attributions