Re: [pygccxml-development] 2 Questions

[Allen B. <al...@vr...>]

Allen Bierbaum wrote:

>Roman Yakovenko wrote:
>
>  
>
>>On 9/12/06, Allen Bierbaum <al...@vr...> wrote:
>>
>>    
>>
>>>I have two questions that I am surprised I haven't run into before. I
>>>hope that both have easy answers.
>>>
>>>1. Base class virtual ignored, but coming in inside derived class 
>>>wrappers.
>>>
>>>I have a base class and derived class like:
>>>
>>>struct Base
>>>{
>>>   virtual const int* getData() const = 0;
>>>};
>>>
>>>struct Child : public Base
>>>{ }
>>>
>>>struct GrandChild : public Child
>>>{
>>>   virtual const int* getData() const;
>>>}
>>>
>>>In my py++ generation script I ignore the getData decl in the Base class
>>>(and the GrandChild).  But py++ still ends up generating wrapper code
>>>for getData for the Child class.  To make matters worse, since it is not
>>>a decl for getData in the Child class I can not ignore it there.  It is
>>>almost like Py++ is seeing the virtual method and deciding that it needs
>>>to provide a wrapper for it in Child even though it is ignored in Base.
>>>Is this a bug in Py++ or is there some way that I can take care of this.
>>>      
>>>
>>Do you know how hard I work to implement this? Basically this is because
>>wrapper classes could not be abstract. Also untill now I didn't have 
>>use case
>>where user ignore some method. May be I will have to take a look on it.
>>    
>>
>
>Can you give me a pointer to where the logic for this is so I can take a 
>look at fixing it?
>  
>
Ok, this didn't work out so well.  I found a way to ignore these methods 
but this made it so the wrapper didn't generate a function at all.  
Which in turn makes the wrapper a pure class that can be instantiated 
and thus the compile fails.  It seems like what I would want here is for 
the wrapper class to generate a method but then for the exposer for the 
real class to not generate bindings for that method.  Unfortunately I 
don't see a way to do this right now. :(

-Allen

>  
>
>>>2. The alternative option would be to just wrap the method correctly,
>>>but how can I wrap returning a memory buffer (array) of arbitrary 
>>>length?
>>>
>>>Is there a way to wrap this method so it will return a const wrapper
>>>around this data buffer to make it look like a python list?  If so what
>>>is the easiest way to do it and do I really need to wait for MB's method
>>>transformer code to do it right?
>>>      
>>>
>>You don't have to wait, you can join and help :-). Take a look on 
>>TnFOX Python
>>bindings, they deal with the same problem ( image classes ). It uses 
>>indexing
>>suite v2 to solve the problem.
>>
>>    
>>
>This will probably be the long term solution for me.  Right now I just 
>need to get my bindings compiling again so I can get some short term 
>work done.
>
>Thanks,
>Allen
>
>
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