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Doc Bug #34697 Undocumented behaviour: class definition before use
Submitted: 2005-10-01 03:12 UTC Modified: 2006-09-08 11:37 UTC
From: direvus at gmail dot com Assigned: nlopess (profile)
Status: Closed Package: Documentation problem
PHP Version: Irrelevant OS: Linux
Private report: No CVE-ID: None
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 [2005-10-01 03:12 UTC] direvus at gmail dot com 
Description:
------------
In the php5 migration guide, we have

"In some cases classes must be declared before used. It only happens only if some of the new features of PHP 5 are used. Otherwise the behaviour is the old."

I request that this behaviour be documented properly (which features?  And why?) in the manual chapter on Classes and Objects in PHP5.

I think for most people who are accustomed to PHP definition conventions, this will come as a surprise.  Functions never need to be declared before use.  Even methods within a class definition need not be declared before use.  So why do we have this strange requirement in the declaration of classes?

This vague mention in the migration guide really isn't sufficient ... it's a strange and opaque behaviour whether you're migrating code or not.

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 [2005-10-02 18:21 UTC] nlopess@php.net 
I think it is clear enough.
It says that if you use the "new" PHP 5 features (interfaces, inheritance,..) you must declare the class before using it.
 [2005-10-02 22:26 UTC] direvus at gmail dot com 
No, it doesn't.

It says "some of the new features of PHP5".  That's extremely non-specific.  It could mean that only a couple of the new features cause the restriction, or it could mean that all of them do.

And I'd like to reiterate my point that, regardless of how clear the mention is, it is not where it needs to be.  It needs to be in the manual *and* in the migration guide.

This is a significant (and again, peculiar) property of PHP5 class syntax.  It's just not right to leave it out of the manual.

Whether you think the existing sentence is sufficient or not, how is the manual not improved by adding this?
 [2005-10-02 22:58 UTC] nlopess@php.net 
I doubt anyone will know exactly what are the features that will make you have to declare the class prior of its usage. Anyway, declaring the class before its usage has some performance advantages.

However I couldn't find this info in the language.oop5 chapter, so I'm leaving this open to add a note to that page.
 [2005-10-03 00:58 UTC] direvus at gmail dot com 
> I doubt anyone will know exactly what are the features that will make
you have to declare the class prior of its usage.

Well somebody wrote the code that causes this behaviour, so somebody must know about it.  Unless it's unintended.

> Anyway, declaring the
class before its usage has some performance advantages.

That's good to know, and should also be noted in the manual.

Don't get me wrong, I'm all for declaring classes prior to usage.  I think it's much better programming style.  But there's a big difference between "it's good style" and "the language requires it".  A difference that needs to be well documented.
 [2006-09-06 19:39 UTC] colder@php.net 
This bug has been fixed in the documentation's XML sources. Since the
online and downloadable versions of the documentation need some time
to get updated, we would like to ask you to be a bit patient.

Thank you for the report, and for helping us make our documentation better.
 [2006-09-07 10:16 UTC] nlopess@php.net 
you have fixed it in the wrong way. I'll take this one.
 [2006-09-08 11:37 UTC] nlopess@php.net 
This bug has been fixed in the documentation's XML sources. Since the
online and downloadable versions of the documentation need some time
to get updated, we would like to ask you to be a bit patient.

Thank you for the report, and for helping us make our documentation better.
 [2020-02-07 06:11 UTC] phpdocbot@php.net 
Automatic comment on behalf of colder
Revision: http://git.php.net/?p=doc/en.git;a=commit;h=73f8a64c985302411fff40a1d186c9ef424b6970
Log: Fix #34697 (Remove ambiguity)
 
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