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digitalmars.D - Is this a bug?

reply freeagle <freeagle inmail.sk> writes:
I have a class BaseWindow
{
Dimension2D size()
	{
		return _size;
	}

abstract void size(Dimension2D size);
}

and derived class Win32Window : BaseWindow
{
void size(Dimension2D size)
{
	_size.set(size);
}
}

lets say i have a reference to class Win32Window. When i try to call 
method _window.size(), compiler complains it doesn't match arguments 
size(Dimension2D). Until i specify is to 
(cast(BaseWindow)_window).size(). Why??
Jul 08 2006
parent reply Tom S <h3r3tic remove.mat.uni.torun.pl> writes:
freeagle wrote:

 I have a class BaseWindow
 {
 Dimension2D size()
     {
         return _size;
     }
 
 abstract void size(Dimension2D size);
 }
 
 and derived class Win32Window : BaseWindow
 {
 void size(Dimension2D size)
 {
     _size.set(size);
 }
 }
 
 lets say i have a reference to class Win32Window. When i try to call 
 method _window.size(), compiler complains it doesn't match arguments 
 size(Dimension2D). Until i specify is to 
 (cast(BaseWindow)_window).size(). Why??


I don't remember the exact reason, but try aliasing 'size' from the 
BaseWindow's scope, like:

class Win32Window : BaseWindow {
void size(Dimension2D size) {
.....
}

alias super.size size;    // iirc
}


-- 
Tomasz Stachowiak  /+ a.k.a. h3r3tic +/
Jul 08 2006
parent reply freeagle <freeagle inmail.sk> writes:
Tom S wrote:

 freeagle wrote:

 I have a class BaseWindow
 {
 Dimension2D size()
     {
         return _size;
     }

 abstract void size(Dimension2D size);
 }

 and derived class Win32Window : BaseWindow
 {
 void size(Dimension2D size)
 {
     _size.set(size);
 }
 }

 lets say i have a reference to class Win32Window. When i try to call 
 method _window.size(), compiler complains it doesn't match arguments 
 size(Dimension2D). Until i specify is to 
 (cast(BaseWindow)_window).size(). Why??


 
 I don't remember the exact reason, but try aliasing 'size' from the 
 BaseWindow's scope, like:
 
 class Win32Window : BaseWindow {
 void size(Dimension2D size) {
 .....
 }
 
 alias super.size size;    // iirc
 }
 
 


the problem is not that i have to type a bit more to actually call the 
method, i just don't understand why its not part of Win32Window 
interface, when Win32Window class is publicly derived from BaseWindow 
defining public method Dimension2D size();
Jul 08 2006
next sibling parent reply Tom S <h3r3tic remove.mat.uni.torun.pl> writes:
freeagle wrote:

 the problem is not that i have to type a bit more to actually call the 
 method, i just don't understand why its not part of Win32Window 
 interface, when Win32Window class is publicly derived from BaseWindow 
 defining public method Dimension2D size();


That may be because of the symbol resolution method that is currently 
being attacked in various posts. In that one example of yours, the 
compiler figures out that you want a 'size' function of the Win32Window, 
it checks it and cant see the right version. It doesnt check the base 
class because of how the method resolution works. Weird, yeah :P


-- 
Tomasz Stachowiak  /+ a.k.a. h3r3tic +/
Jul 08 2006
parent reply freeagle <freeagle inmail.sk> writes:
Tom S wrote:

 freeagle wrote:

 the problem is not that i have to type a bit more to actually call the 
 method, i just don't understand why its not part of Win32Window 
 interface, when Win32Window class is publicly derived from BaseWindow 
 defining public method Dimension2D size();


 
 That may be because of the symbol resolution method that is currently 
 being attacked in various posts. In that one example of yours, the 
 compiler figures out that you want a 'size' function of the Win32Window, 
 it checks it and cant see the right version. It doesnt check the base 
 class because of how the method resolution works. Weird, yeah :P
 
 


well yeah, this way, you have to show whole inheritance tree to the user 
of the lib so he can use it. I think this damages encapsulation. I dont 
want the user to know there is a BaseWindow class, i want him to be 
happy just with a knowledge of Win32Window class.
Jul 08 2006
parent freeagle <freeagle inmail.sk> writes:
freeagle wrote:

 Tom S wrote:

 freeagle wrote:

 the problem is not that i have to type a bit more to actually call 
 the method, i just don't understand why its not part of Win32Window 
 interface, when Win32Window class is publicly derived from BaseWindow 
 defining public method Dimension2D size();


 That may be because of the symbol resolution method that is currently 
 being attacked in various posts. In that one example of yours, the 
 compiler figures out that you want a 'size' function of the 
 Win32Window, it checks it and cant see the right version. It doesnt 
 check the base class because of how the method resolution works. 
 Weird, yeah :P


 
 well yeah, this way, you have to show whole inheritance tree to the user 
 of the lib so he can use it. I think this damages encapsulation. I dont 
 want the user to know there is a BaseWindow class, i want him to be 
 happy just with a knowledge of Win32Window class.


ok, you dont, im taking back my last statements ;) thanks guys for the help
Jul 09 2006
prev sibling parent Bruno Medeiros <brunodomedeirosATgmail SPAM.com> writes:
freeagle wrote:

 Tom S wrote:

 freeagle wrote:

 I have a class BaseWindow
 {
 Dimension2D size()
     {
         return _size;
     }

 abstract void size(Dimension2D size);
 }

 and derived class Win32Window : BaseWindow
 {
 void size(Dimension2D size)
 {
     _size.set(size);
 }
 }

 lets say i have a reference to class Win32Window. When i try to call 
 method _window.size(), compiler complains it doesn't match arguments 
 size(Dimension2D). Until i specify is to 
 (cast(BaseWindow)_window).size(). Why??


 I don't remember the exact reason, but try aliasing 'size' from the 
 BaseWindow's scope, like:

 class Win32Window : BaseWindow {
 void size(Dimension2D size) {
 .....
 }

 alias super.size size;    // iirc
 }


 
 the problem is not that i have to type a bit more to actually call the 
 method, i just don't understand why its not part of Win32Window 
 interface, when Win32Window class is publicly derived from BaseWindow 
 defining public method Dimension2D size();


The relevant doc specification, is on 
http://www.digitalmars.com/d/function.html , Function Inheritance and 
Overriding:
"However, when doing overload resolution, the functions in the base 
class are not considered:
[...]
To consider the base class's functions in the overload resolution 
process, use an AliasDeclaration:"

I'm also not sure if this is the ideal behavior.

-- 
Bruno Medeiros - CS/E student
http://www.prowiki.org/wiki4d/wiki.cgi?BrunoMedeiros#D
Jul 09 2006