PYTHON function_exists

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Python replacement for PHP's function_exists [ edit | history ]
This snipplet only works if you want to check if a function exists in your current module, but not inside os.path or so: 

funcName = "MyFunction"

try:
	func = locals()[ funcName ]
	if callable( func ):
		func( argumentA, argumentB )      # depends on function, of course
except:
	print funcName, "is not defined"



# please note I'm a beginner, don't punish me if it is not the most beautiful way ;-)

An actual replacement rather than a snippet: 

import types

def function_exists(fun):
  '''As in PHP, fun is tested as a name, not an object as is common in Python.'''
  try:
    ret = type(eval(str(fun))
    return ret in (types.FunctionType, types.BuiltinFunctionType)
  except NameError:
    return False

PHP function_exists

PHP original manual for function_exists [ show | php.net ]

function_exists

(PHP 4, PHP 5)

function_exists — Return TRUE if the given function has been defined

Description

bool function_exists ( string $function_name )

Checks the list of defined functions, both built-in (internal) and user-defined, for function_name .

Parameters

function_name

The function name, as a string.

Return Values

Returns TRUE if function_name exists and is a function, FALSE otherwise.

Note: This function will return FALSE for constructs, such as include_once() and echo().

Examples

Example #1 function_exists() example

<?php
if (function_exists('imap_open')) {
    echo "IMAP functions are available.<br />\n";
} else {
    echo "IMAP functions are not available.<br />\n";
}
?>

Notes

Note: A function name may exist even if the function itself is unusable due to configuration or compiling options (with the image functions being an example).

See Also

Function handling Functions
PHP Manual