Daniele Varrazzo schrieb:
>  Hello,
>  
>  i am trying (mostly successfully, thank you! :D) to wrap the 
>  SpiderMonkey library (http://www.mozilla.org/js/spidermonkey/) into 
>  Python using ctypes. The wrapper has been built using the ctypeslib 
>  CodeGenerator.
>  
>  I have to set up a structure, basically a vtable, so i have to fill a 
>  structure members with function pointers. These function are provided by 
>  the library itself, i don't have to setup Python callbacks here.
>  
>  The structure defined like:
>  
>       struct JSClass {
>           const char          *name;
>           uint32              flags;
>           JSPropertyOp        addProperty;
>           JSPropertyOp        delProperty;
>           ... and so on...
>       }
>  
>  I have to do the C equivalent of:
>  
>       JSClass global_class = {
>           "global",0,
>           JS_PropertyStub,JS_PropertyStub,
>           ... etc
>       };
>  
>  Up to now, the only way i managed to make it work is:
>  
>       global_class = JSClass('global', 0,
>           JSPropertyOp(JS_PropertyStub),
>           JSPropertyOp(JS_PropertyStub),
>           ...
>  
>  while the most obvious solution (directly passing JS_PropertyStub to the 
>  Python wrapped structure) leads to a TypeError (incompatible types, 
>  _FuncPtr instance instead of CFunctionType instance).
>  
>  Even if the above solution works, i am concerned that, when C code will 
>  access this vtable, it will call a Python function which in turn will 
>  call the desired function, resulting in an extra Python roundtrip for 
>  each call where only C code should have been involved.
>  
>  Is it true? If so, how can i pass a pointer to a C function without such 
>  double wrapping?

You could probably use cast.  Something like this (I assume JS_PropertyStub is
a foreign function loaded from a shared lib), and JS_PropertyOp is something created
with a call to CFUNCTYPE(...):

  JSClass('global', 0,
    cast(JS_PropertyStub, JSPropertyOp),

>  Thanks in advance,
>  
>  Daniele
>  
>  P.S. what is the best place to report a bug in the CodeGenerator?

You can post it here.

Thomas


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