How to reference class instance from nested function

antun

If I have a class with a nested function inside of another function:

class MyClass {
    function MyClass() {
        $this->myVar = 'foo';
        function startElement() {
            echo $this->myVar;
        }
    }
}

... how do I reference a class property (such as myVar above) from a nested function? Is there some sort of "parent" concept?

-Antun

ahundiak

I'm pretty sure that php does not support nested functions.

class MyClass 
{
  function MyClass() 
  {
    $this->myVar = 'foo';
  }
  function startElement() {
    echo $this->myVar;
  }
}

neon

Classes have only methods no functions. And I don't no if that what you are doing is possible, but anyway it's wrong way to do it.

class myFirstClass {
         var $myVar;
         function myFirstMethod() {
                       $this->mySecondMethod();
         }
          function mySecondMethod() {
                      $this->myVar = "foobar";
         }
}
$object = &new myFirstClass;
$object->myFirstMethod();

Consider reading about OO programing.

antun

I know PHP does allow nested functions, because the manual says it does. However I'm not sure about the implications of a function inside of a class method.

-Antun

neon

Simply not possible. Functions are always in global scope. You are trying to implement a function inside a method, but "functions" inside classes are always handled as methods. So what I'm saying is that it leads us into method inside method case, which is nested method. It you feel that confusing, blain me..

antun

Hey neon

Actually my last post was in response to ahundiak, who said that PHP doesn't support nested functions, and you were right to point out that functions inside classes are always treated as methods.

In that case, what I really need to know is how do I implement a callback reference for a method:

Say I'm parsing XML. I can define startElement() in my script and the following will work:

xml_set_element_handler($xml_parser, "startElement", "endElement");

but if startElement is a method of a class, how do I call the xml_set_element_handler() method?

xml_set_element_handler($xml_parser, "this->startElement", "this->endElement");

-Antun

neon

I kinda knew the real problem was something like this.
See xml_set_object() function.

       $this->parser = xml_parser_create();
        xml_set_object($this->parser, &$this);
        xml_set_element_handler($this->parser, "tag_open", "tag_close");
        xml_set_character_data_handler($this->parser, "cdata");

ahundiak

Can you give me a link to where in the manual it says that php supports nested functions?

The chapter on functions says:

Any valid PHP code may appear inside a function, even other functions and class definitions.

But all that is happening here is that you are defining the function. The function itself is not nested and has no information about the outer function. So it's really not nested.

The main reason php lets you do this is to allow bringing in conditional include files.

ahundiak

anton,
You can use a method as a callback by using an array. Something like

sort($list,array($object,'method_name'));

Look in the user comments in the objects chapter in the manual.

antun

I must have misunderstood "nested". I guess that it implies specific behavior; I though it meant that one function was allowed to be inside of another. This page:

http://www.php.net/manual/en/functions.php#functions.user-defined

... under the section Example 13-3. Functions within functions, shows what I thought nested functions were.

Anyway, I've figured out how to do a callback to a method, so I'm chuffed:

xml_set_element_handler($xml_parser, array( &$this, "startElement"), array( &$this, "endElement" ));

Take care,

Antun