On 19 July 2013 17:36, Daniel Lowrey <rdlow...@gmail.com> wrote: > I have a simple question about the callability of language constructs and > whether or not that's something that might change in the future. Consider: > > var_dump(is_callable('echo')); // bool(false) > var_dump(call_user_func('echo', 'foo')); // E_WARNING > echo('foo'); // foo > > var_dump(is_callable('isset')); // bool(false) > var_dump(isset(1)); // E_ERROR > > Obviously this behavior arises because tokens like `echo` and `isset` are > language constructs and not functions. I can see some potential benefits > for working around this. For example, say I want to filter only the NULL > elements from an array but keep the other "falsy" values. Recognizing > `isset` as callable would allow me to do this: > > var_dump(array_filter([0, FALSE, NULL], 'isset')); // [0, FALSE] >
array_filter([…], 'is_null'); > > Of course, this limitation is trivial to work around with a userland > callback to check for the explicit NULL equivalency, but it would be nice > to avoid the hassle. So my question is ... > > How deeply ingrained into the engine is this behavior? Is there any chance > of language constructs ever passing the tests for callability or is that > just a pipe dream that's not worth the implementation effort? >