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Date: Wed, 26 Aug 2015 11:10:34 +0100
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Subject: Re: [PHP-DEV] PHP 7.1 - Address PHPSadness #28?
From: rowan.collins@gmail.com (Rowan Collins)

Scott Arciszewski wrote on 26/08/2015 04:09:
> Hi everybody,
>
> Would anyone be interested in adding another helper like
> isset()/empty() simply called exists() which would return true if the
> variable is defined in the current scope (i.e. without raising an
> E_NOTICE)?

My answer to this would be a very loud "no".

I have written at length about this on StackOverflow: 
http://stackoverflow.com/a/18646568/157957

In short, if your algorithm relies on knowing whether, anywhere in the 
preceding scope, a variable has been implicitly "declared" (in as much 
as that concept has any meaning in PHP), that algorithm is broken. If it 
relies on knowing whether a variable has been changed from its initial 
state, then isset() will do exactly what you want.

Note that many people looking for examples of this "problem" start 
mentioning array keys and object properties; we have functions for 
checking existence of those, so please don't waste time on such examples.

Regards,
-- 
Rowan Collins
[IMSoP]