php: can I create and call function inside a class method?

Question

is it possible to create function inside a class method and how do I call it ?

i.e.

class Foo
{
    function bar($attr)
    {
       if($attr == 1)
       {
          return "call function do_something_with_attr($attr)";
       }
       else
       {
          return $attr;
       }

       function do_something_with_attr($atr)
       {
          do something
          ...
          ...
          return $output;
       }
    }
}

thank you in advance

Could the same not be accomplished using a normal (perhaps static) class method? — Matt Lowden
– Matt Lowden, Commented Jan 16, 2011 at 23:59

Russell Hankins · Accepted Answer · 2016-08-30 16:00:30Z

13

Yes. As of PHP 5.3, You can use anonymous functions for this:

class Foo
{
    function bar($attr)
    {
        $do_something_with_attr = function($atr)
        {
            //do something
            //...
            //...
            $output = $atr * 2;
            return $output;
        };

        if ($attr == 1)
        {
            return $do_something_with_attr($attr);
        }
        else
        {
            return $attr;
        }
     }
}

answered Aug 30, 2016 at 16:00

Russell Hankins

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Comments

Ignacio Vazquez-Abrams · Accepted Answer · 2011-01-17 00:01:32Z

10

It can be done, but since functions are defined in the global scope this will result in an error if the method is called twice since the PHP engine will consider the function to be redefined during the second call.

answered Jan 17, 2011 at 0:01

Ignacio Vazquez-Abrams

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3 Comments

m1k3y3 Over a year ago

I am getting error as Ignacio wrote. Zerkms, could you please explain in more details how to solve with function_exists() ? - Thank You.

Scuzzy Over a year ago

The php documentation is a wonderful thing php.net/manual/en/function.function-exists.php

netcoder Over a year ago

@m1k3y02: You shouldn't have to declare global functions within methods. Declare other methods with protected or private visibility instead, and call them using $this. Unless you really really need a global function...

joan16v · Accepted Answer · 2014-07-10 10:05:25Z

3

Use "function_exists" to avoid errors.

class Foo
{
    function bar($attr)
    {

       if (!function_exists("do_something_with_attr")){ 
           function do_something_with_attr($atr)
           {
              do something
              ...
              ...
              return $output;
           }
       }

       if($attr == 1)
       {
          return do_something_with_attr($attr);
       }
       else
       {
          return $attr;
       }


    }
}

answered Jul 10, 2014 at 10:05

joan16v

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