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                                  is_callable

   (PHP 4 >= 4.0.6)
   is_callable --  Verify that the contents of a variable can be called
   as a function

Description

   bool is_callable ( mixed var [, bool syntax_only [, string
   callable_name]])

   Verify that the contents of a variable can be called as a function.
   This can check that a simple variable contains the name of a valid
   function, or that an array contains a properly encoded object and
   function name.

   The var parameter can be either the name of a function stored in a
   string variable, or an object and the name of a method within the
   object, like this:
   array($SomeObject, 'MethodName')

   If the syntax_only argument is TRUE the function only verifies that
   var might be a function or method. It will only reject simple
   variables that are not strings, or an array that does not have a valid
   structure to be used as a callback. The valid ones are supposed to
   have only 2 entries, the first of which is an object or a string, and
   the second a string.

   The callable_name argument receives the "callable name". In the
   example below it's "someClass:someMethod". Note, however, that despite
   the implication that someClass::SomeMethod() is a callable static
   method, this is not the case.

   <?php
   //  How to check a variable to see if it can be called
   //  as a function.
   //
   //  Simple variable containing a function
   //
   function someFunction() {
   }
   $functionVariable = 'someFunction';
   var_dump(is_callable($functionVariable, false, $callable_name));  //
   bool(true)
   echo $callable_name, "\n";  // someFunction
   //
   //  Array containing a method
   //
   class someClass {
     function someMethod() {
     }
   }
   $anObject = new someClass();
   $methodVariable = array($anObject, 'someMethod');
   var_dump(is_callable($methodVariable, true,
   $callable_name));  //  bool(true)
   echo $callable_name, "\n";  //  someClass:someMethod
   ?>
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