Re: Language constructs and callability
2013/7/19 Peter Cowburn <[email protected]>
> On 19 July 2013 17:36, Daniel Lowrey <[email protected]> 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');
>
> That would do the opposite of what you want.
>
> >
> > 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?
> >
>
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