# Use of 'self' in static function in subclass - Thread: https://externals.io/message/10200 - Original archive: https://news-web.php.net/php.internals/10200 - Started by Bert Slagter on 2004-06-01T13:11:29+00:00 - Messages: 12 - Reply by email to internals@lists.php.net - More for agents: search with https://externals.io/search.md?q={query} · JSON API at https://externals.io/api · documentation at https://externals.io/llms.txt --- ## #10200 — Bert Slagter — 2004-06-01T13:11:29+00:00 URL: https://externals.io/message/10200#10200 Hi All, I have a class and a subclass, both with a static method: In this case I expect to find 'Baz' on my screen, but I get the following: "Fatal error: Call to undefined method Foo::baz() in d:\htdocs_php5\ProBase2\TRUNK\probase\libsys\test5.php on line 7". This is in PHP5 RC2. Somehow this behaviour seems logical, on the other hand I don't think it's desired. I think that 'self' should point to the current class, even if the static method resides in a parent class. Is this 'self'-behaviour intended? Bert --- ## #10201 — Stephan Schmidt — 2004-06-01T13:21:48+00:00 URL: https://externals.io/message/10200#10201 · In reply to: #10200 Hi, > Somehow this behaviour seems logical, on the other hand I don't think > it's desired. I think that 'self' should point to the current class, > even if the static method resides in a parent class. > > Is this 'self'-behaviour intended? Furthermore this renders the template-method pattern quite useless, so IMHO it should be changed. Stephan --- ## #10202 — Hans Lellelid — 2004-06-01T13:43:02+00:00 URL: https://externals.io/message/10200#10202 · In reply to: #10200 Bert Slagter wrote: > Hi All, > > I have a class and a subclass, both with a static method: > > class Foo > { > static function Bar() > { > self::Baz(); > } > } > > class Foo2 extends Foo > { > static function Baz() > { > echo 'Baz'; > } > } > > Foo2::Bar(); > ?> > > In this case I expect to find 'Baz' on my screen, but I get the > following: "Fatal error: Call to undefined method Foo::baz() in > d:\htdocs_php5\ProBase2\TRUNK\probase\libsys\test5.php on line 7". > > This is in PHP5 RC2. > > Somehow this behaviour seems logical, on the other hand I don't think > it's desired. I think that 'self' should point to the current class, > even if the static method resides in a parent class. Yeah, this probably should change to be consistent. I've been living fine with the current behavior, but considering self::*() will automatically invoke the parent class' method if none is defined in current class, then it should probably also work the other way around. My .02, Hans --- ## #10204 — Ferdinand Beyer — 2004-06-01T14:02:43+00:00 URL: https://externals.io/message/10200#10204 · In reply to: #10200 > Furthermore this renders the template-method pattern quite useless, so > IMHO it should be changed. He should define an abstract method Foo::Baz() here. -- Ferdinand Beyer > > > > […] > > useless, so > > > […] > > > He should define an abstract method Foo::Baz() here. > Yes, I agree that design-wise that would be better -- but it will still fail w/ E_FATAL in PHP if the method is abstract ("cannot call abstract method Foo::Baz() in ...."). Hans --- ## #10208 — Bert Slagter — 2004-06-01T14:19:57+00:00 URL: https://externals.io/message/10200#10208 · In reply to: #10204 Ferdinand Beyer wrote: > He should define an abstract method Foo::Baz() here. > This is a minimal testcase, in my real life situation there indeed is a 'abstract static function Baz();' in Class Foo. But indeed, then a "Fatal error: Cannot call abstract method Foo::Baz() in.." arises.. Bert --- ## #10230 — Timm Friebe — 2004-06-01T19:13:54+00:00 URL: https://externals.io/message/10200#10230 · In reply to: #10200 > Hi All, > > I have a class and a subclass, both with a static method: [...] > Somehow this behaviour seems logical, on the other hand I don't think > it's desired. I think that 'self' should point to the current class, > even if the static method resides in a parent class. > > Is this 'self'-behaviour intended? Yes: self is bound at compiletime. It would need to be changed to evaluation at runtime und would be far more useful then. This has been reported a couple of times, in slight variations: http://zend.com/lists/engine2/200307/msg00033.html http://zend.com/lists/engine2/200307/msg00036.html http://zend.com/lists/engine2/200309/msg00024.html In one of these, Marcus suggested a new keyword "this" which would behave like a run-time self, e.g: class Test { public static function getInstance() { return new this(); } } class Foo extends Test { } var_dump(Foo::getInstance()); would output "object(foo)" instead of "object(test)". I wouldn't mind chaning self in the first place, though. - Timm --- ## #10231 — Ferdinand Beyer — 2004-06-01T19:47:49+00:00 URL: https://externals.io/message/10200#10231 · In reply to: #10200 > Yes: self is bound at compiletime. It would need to be changed to > evaluation at runtime und would be far more useful then. > > [...] > > I wouldn't mind chaning self in the first place, though. I prefer your solution to evaluate self at runtime instead of adding a new keyword 'this'. The second one would only be confused with $this. Many people (including me) are already familiar with 'self' and expect it to refer to the class from within it is called. -- Ferdinand Beyer > > > > […] > > > I prefer your solution to evaluate self at runtime instead of adding a > new keyword 'this'. The second one would only be confused with > $this. Many people (including me) are already familiar with 'self' and > expect it to refer to the class from within it is called. > Yeah +1 on self:: binding at runtime. I can't really imagine a case where you would want to refer to 'self' as the class that contains the method *and not* the overridden method in invoked class (if it exists). Binding this at runtime will introduce many new design possibilities with static classes and will also make self:: consistent with $this-> behavior for objects. Hans --- ## #10236 — Adam Bregenzer — 2004-06-02T00:26:25+00:00 URL: https://externals.io/message/10200#10236 · In reply to: #10235 > Yeah +1 on self:: binding at runtime. I can't really imagine a case > where you would want to refer to 'self' as the class that contains the > method *and not* the overridden method in invoked class (if it exists). > Binding this at runtime will introduce many new design possibilities > with static classes and will also make self:: consistent with $this-> > behavior for objects. +1, I agree completely. I think it is critical to have a way to be able to have a static method call another static method in the same class that respects inheritance. If a developer wanted a call to not respect inheritance the class's name can be used instead of self with the same results (increased code maintenance should the class name change notwithstanding). -- Adam Bregenzer adam@bregenzer.net http://adam.bregenzer.net/ --- ## #10237 — Jevon Wright — 2004-06-02T00:36:26+00:00 URL: https://externals.io/message/10200#10237 · In reply to: #10236 It's something I noticed, too. Consider this: class A { function a() { return $this::b(); } function b() { return 1; } } class B extends A { function b() { return 2; } } If I call $b = new B(); echo $b->a(); No matter what combination of this, self, parent, ... - I could never get B's property. I was led to believe that this is actually normal for OO designs (is it? If so, ignore me). But it would be awesome if self or $this (ONLY one of them, if they currently perform the same function) actually referred to the top class - ie. B::b() in this case. Is this what this suggestion would suggest? Thanks, Jevon ----- Original Message ----- From: "Adam Bregenzer" To: "Hans Lellelid" Cc: "Ferdinand Beyer" ; "Timm Friebe" ; Sent: Wednesday, June 02, 2004 12:26 PM Subject: Re: [PHP-DEV] Use of 'self' in static function in subclass > > > […] > > +1, I agree completely. I think it is critical to have a way to be able > to have a static method call another static method in the same class > that respects inheritance. If a developer wanted a call to not respect > inheritance the class's name can be used instead of self with the same > results (increased code maintenance should the class name change > notwithstanding). > > -- > Adam Bregenzer > adam@bregenzer.net > http://adam.bregenzer.net/ --- ## #10255 — Andi Gutmans — 2004-06-03T08:01:15+00:00 URL: https://externals.io/message/10200#10255 · In reply to: #10200 I don't agree as I don't think static methods should be virtual. This is what $this-> exists for. Re-design...! Andi At 03:11 PM 6/1/2004 +0200, Bert Slagter wrote: >Hi All, > >I have a class and a subclass, both with a static method: > >class Foo >{ > static function Bar() > { > self::Baz(); > } >} > >class Foo2 extends Foo >{ > static function Baz() > { > echo 'Baz'; > } >} > >Foo2::Bar(); >?> > >In this case I expect to find 'Baz' on my screen, but I get the following: >"Fatal error: Call to undefined method Foo::baz() in >d:\htdocs_php5\ProBase2\TRUNK\probase\libsys\test5.php on line 7". > >This is in PHP5 RC2. > >Somehow this behaviour seems logical, on the other hand I don't think it's >desired. I think that 'self' should point to the current class, even if >the static method resides in a parent class. > >Is this 'self'-behaviour intended? > >Bert