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Date: Wed, 11 Mar 2009 18:09:25 -0500
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Subject: Re: [PHP-DEV] non static function called as static one
From: greg@chiaraquartet.net (Greg Beaver)

Olivier Doucet wrote:
> Hi,
> 
> 
>> not sure if this was mentioned on the general list but, i believe what
>> youre describing is documented in the manual under php5 classes/objects ->
>> "the basics":
>>
>> http://www.php.net/manual/en/language.oop5.basic.php
>>
>> $this is a reference to the calling object (usually the object to which
>> the method belongs, but can be another object, if the method is called
>> statically <http://www.php.net/manual/en/language.oop5.static.php> from
>> the context of a secondary object).
>>
>> -nathan
>>
> I know this behaviour is fully documented, but I was more concerned about
> "is it a 'normal' behaviour ?". How can a programmer controls the class he

Yes

> wrote, and make it absolutely bugproof ? How can he detect his function was
> called in a static context and forbid it (or write specific code for) ?

You can't unless you do some obtuse kind of:

if (isset($this) && $this instanceof MyClass)

But even this results in terrible and subtle mistakes if you happen to
call a "static" method from within a method of a subclass of MyClass.

instead use

static function blah()

for static functions, and $this simply will not be available.

Don't call non-static methods statically unless you want trouble.

"static" was introduced precisely for this reason.

Trying to make functions work as both dynamic and static is a disaster,
and we have had endless intractable problems with the most prevalent
implementation of this double design in the PEAR base class,
specifically with PEAR::raiseError().  Just don't do it.

Greg