Re: [pygccxml-development] Py++ generates wrappers for final classes

[Julian S. <jul...@rs...>]

Hello,

many thanks for your quick reply.

Roman Yakovenko wrote:
> On 7/9/07, Julian Scheid <jul...@rs...> wrote:
>> I've run into a problem with Py++ (both with 0.9.0 and with trunk) when
>> trying to expose a class like this:
>>
>>    class Foo
>>    {
>>     public:
>>      virtual void bar() {}
>>     private:
>>      Foo() {}
>>    };
> 
> What compiler do you use? I just checked this on MSVC 7.1 and it works 
> fine.
> I attach the generated code.

That was a bad example - it actually compiles for me, too. But the 
following won't compile on g++ 3.x (tested 3.4.2, 3.4.1 and 3.3.1) with 
"base `Foo' with only non-default constructor in class without a 
constructor". It works fine on g++ 4.0.2 though... so maybe it's not 
something that needs to be fixed after all.

     class Foo
     {
      public:
       virtual void foo() {}
      private:
       Foo(bool) {}
     };

I've attached the generated code as well. But it looks like it's sort of 
a non-issue after all, sorry if I wasted your time.

>> In the long term, I guess the proper fix is to not create wrappers for
>> final classes.
> 
> There is no such definition in C++ as "final class". Private
> constructor is "public" for a function or another class. ( friend )

True, but wouldn't the private constructor have to be "public" from the 
point of view of the deriving class? If you take a closed API that uses 
private constructors like this, for example, it effectively means that 
you can't subclass the class in question short of tinkering with the header.

I guess at any rate it would be great if Py++ could add a (simple) way 
to explicitly disable wrapper generation for a given class.

>> Is there a short-term workaround for this problem?
> 
> Try this:

I'll give that a try, thanks again for your help!

Julian