Pointers, casting, SetGetWindowLong problem...

[Frits van Bommel]

Chris Warwick wrote:
> "Derek Parnell" <derek at psych.ward> wrote in message 
> news:1f2c01vt6zeaq$.ac8d0velaphe$.dlg at 40tude.net...
>> On Fri, 9 Mar 2007 23:16:34 -0000, Chris Warwick wrote:
>>
>>>     if (window == null)  return DefWindowProcA(handle, msg, wparam, 
>>> lparam);
>>>
>>> but i keep getting an access violation on the if (window == null),
>>>
>> Use this instead ...
>>
>>    if (window is null) ...
>>
>> Because ...
>>
>>    if (window == null)
>>
>> is identical to
>>
>>    if (window.opEquals(null))
>>
>> which will fail if 'window' is null because it needs to use it to 
>> reference
>> the opEquals method.
> 
> So opEquals must be inherited from Object cause I havnt implememented it in 
> my class. So what exactly does this inherited opEquals do? How can an 
> inherited opEquals have any sensible result in descendant classes unless 
> overriden by those subclasses?

Ironically, it returns the result of "this is other" :P.
Unfortunately, execution never gets that far when the left-hand side of 
'==' actually *is* null...
But yes, that method is indeed meant to be overridden by most classes 
that want to be equality-comparable.