(PHP 4 >= 4.0.6, PHP 5)is_callable -- Verify that the contents of a variable can be called as a function
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:
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.