<?php
function someName($val){
return $val;
}
$functionName = "someName";
echo call_user_func($functionName, "Hello, World!"); //calls `someName()`
PD9waHAKICAgIGZ1bmN0aW9uIHNvbWVOYW1lKCR2YWwpewogICAgICAgIHJldHVybiAkdmFsOwogICAgfQoKICAgICRmdW5jdGlvbk5hbWUgPSAic29tZU5hbWUiOwogICAgZWNobyBjYWxsX3VzZXJfZnVuYygkZnVuY3Rpb25OYW1lLCAiSGVsbG8sIFdvcmxkISIpOyAvL2NhbGxzIGBzb21lTmFtZSgpYA==