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Request #33361 $this in static context
Submitted: 2005-06-16 13:14 UTC Modified: 2005-06-16 15:21 UTC
Votes:4
Avg. Score:4.0 ± 1.7
Reproduced:4 of 4 (100.0%)
Same Version:1 (25.0%)
Same OS:1 (25.0%)
From: halmai at nexum dot hu Assigned:
Status: Wont fix Package: Feature/Change Request
PHP Version: 4.3.10 OS: Linux
Private report: No CVE-ID: None
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From: halmai at nexum dot hu
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 [2005-06-16 13:14 UTC] halmai at nexum dot hu 
Description:
------------
I have two classes with one function respectively. 

In any function the variable $this should mean 
- the instance of the class if this function was called as a function of an instance of _that_ class, and 
- it should be undefined (null) if called as a static function.

My problem is that if I call a static function of a class A from a non-static function of class B then in the member function of class A the variable $this denotes the instance of the class B instead of being null.

The fact that in a function of class A the variable $this denotes an instance of class B is really confusing. If it was called statically then $this should be null. 

I know that this is described as normal behaviour but I think this is a useless and senseless feature. In case of accepting my suggestion it would be easy to decide whether a function was called in a static or non-static context.

Reproduce code:
---------------
class A {
  function what_am_i() {
    if ( $this === null ) {
      print "i am not an instance<br>";
    } else {
      print "i am an instance from the class '".get_class( $this )."'.<br>";
    }
  }
}
class B {
  function wrapper() {
    A::what_am_i();  
  }
}
A::what_am_i(); // i am not an instance (this is OK)
$a = new A();
$a -> what_am_i(); // i am an instance from the class 'a'. (this is OK)

$b = new B();
$b -> wrapper();  // i am an instance from the class 'b'. (this should output not an instance)


Expected result:
----------------
i am not an instance
i am an instance from the class 'a'.
i am not an instance


Actual result:
--------------
i am not an instance
i am an instance from the class 'a'.
i am an instance from the class 'b'.

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 [2005-06-16 13:28 UTC] johannes@php.net 
Thank you for taking the time to write to us, but this is not
a bug. Please double-check the documentation available at
http://www.php.net/manual/ and the instructions on how to report
a bug at http://bugs.php.net/how-to-report.php

.
 [2005-06-16 13:39 UTC] halmai at nexum dot hu 
I know that this is not a bug. This is a feature, but a really silly and useless feature.

That's why I reported it as a "feature/change request".
 [2005-06-16 13:52 UTC] halmai at nexum dot hu 
Sorry, I forgot to reopen the state of this report.
 [2005-06-16 13:57 UTC] tony2001@php.net 
As this is not a bug, it won't be changed in 4.3/4.4, because this is a bugfix-only branch.
 [2005-06-16 14:02 UTC] halmai at nexum dot hu 
OK, I unsderstand.

Should I re-report this for version 5. or is it possible somehow to modify the php-version of this report? 

I could simply overwrite the version in the form but I can not reopen the report because I have only the "Wontfix" and "Closed" options.
 [2005-06-16 14:08 UTC] tony2001@php.net 
>Should I re-report this for version 5.
Why? It works perfectly there.
 [2005-06-16 14:33 UTC] halmai at nexum dot hu 
No, it is not perfect in version 5 neither. 

It works the same way in PHP 5.0.4 as in PHP 4.3.10.

So, should I re-report it or can You assign this report to a newer PHP version? If You can, then please do it. Thanks in advance.
 [2005-06-16 14:39 UTC] tony2001@php.net 
It works fine if you declare the method as static.
If you don't do it - it works in the same way as in PHP4 just because of backward compatibility.
 [2005-06-16 14:58 UTC] halmai at nexum dot hu 
In php5 when I use the keyword static then the value of the variable $this will always be null in this function. It's the correct behaviour because a static function can be called only without any instance. 

But if I want to call a function sometimes as an instance function and sometimes without any instances, then I have to omit the keyword static. But in this case I get the silly behaviour of php4, where I can not decide inside a function if it was called in static context or not. 

That's why I think this behaviour should be changed.
 [2005-06-16 15:14 UTC] tony2001@php.net 
As I have already said: it won't be changed in PHP4 and it won't be changed in PHP5 because of BC.
 [2005-06-16 15:21 UTC] halmai at nexum dot hu 
OK, I understand that it will not be changed in PHP4.

If BC stands for backword compatibility, then I do not agree. 

I think this "feature" was not used by too many users but many of them were surprised by this behavior (see earlier bugreports). That's why it should be changed, I think. Maybe in PHP6?

If a feature is senseless and embarrasses some users and any others are not using this feature at all then it could be changed, I think.
 
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