(PECL runkit >= 0.7.0)
runkit_function_rename — Change a function's name
bool runkit_function_rename ( string $funcname , string $newname )
Note: By default, only userspace functions may be removed, renamed, or modified. In order to override internal functions, you must enable the runkit.internal_override setting in php.ini.
funcname
Current function name
newname
New function name
 Returns TRUE on success or FALSE on failure. 
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Licensed under the Creative Commons Attribution License v3.0 or later.
    https://secure.php.net/manual/en/function.runkit-function-rename.php