Re: [pygccxml-development] Basic Py++ questions

[Paul M. <pa...@sc...>]

Roman Yakovenko wrote:
> On Wed, Oct 29, 2008 at 10:31 PM, Paul Melis
> <pyp...@as...> wrote:
>   
>> Roman Yakovenko wrote:
>>     
>>>>> Why do you want to exclude such declarations:
>>>>> * to get "clean" build - without warnings. If so, in this specific
>>>>> case you can decide that you trust Py++ and suppress the warning.
>>>>> * other reasons - please explain.
>>>>>
>>>>>
>>>>>           
>>>> The reason is quite practical. Up till now I have not been able to even
>>>> compile my generated wrappers because of W1005 warnings.
>>>> I simply want to get some version of my wrappers working that I can get
>>>> started with. From there I can work on replacing/handling the issues w.r.t.
>>>> use of non-public classes.
>>>>
>>>>         
>>> It sounds like a bug. Can you send me simple test case. I would like
>>> to improve the situation.
>>>
>>>       
>> After some digging it seems to be caused by the following pattern:
>> - the code I'm wrapping uses its own smart pointer class, say smart_ptr<T>
>> - the code contains a class, say C, with a protected inner class, say I
>> - the smart_ptr class has one or more methods that either return or use
>> a pointer to C::I
>>
>> In the gccxml I see lines <Class ... artificial="1"
>> demangled="smart_ptr<C::I>;" mangled="..."  name="smart_ptr<C::I>" />,
>> which probably make Py++ generate wrappers for the smart_ptr methods.
>>     
>
> No, it doesn't help. I don't understand why Py++ still generates them.
> Are the functions [pure] virtual?
>
> Also, I suggest you to read the following link:
> http://language-binding.net/pyplusplus/troubleshooting_guide/smart_ptrs/smart_ptrs.html
>   
I thought I had found what was going on. Take, for example, the 
following class:

class Outer
{
protected:
    struct Inner
    {
        Inner() {}

        Inner(const Inner& obj)
        {
            field = obj.field;
        }

        Inner& operator = (const Inner& obj)
        {
            field = obj.field;
            return *this;
        }

        int field;
    };
};

When I run the Python script at the end of this mail I get

INFO Parsing source file "all.h" ...
INFO gccxml cmd: /home/paul/local/bin/gccxml  -I"."   "all.h" 
-fxml="/tmp/tmpQ34w-p.xml"
INFO GCCXML version - 0.9

WARNING: Outer::Inner::Inner(Outer::Inner const & obj) [copy constructor]
 > compilation error W1005: Py++ cannot expose function that takes as
 > argument/returns instance of non-public class. Generated code will not
 > compile.

WARNING: Outer::Inner & Outer::Inner::operator=(Outer::Inner const & 
obj) [member operator]
 > compilation error W1005: Py++ cannot expose function that takes as
 > argument/returns instance of non-public class. Generated code will not
 > compile.

INFO: file "generated.cpp" - updated( 0.000000 seconds )

So it LOOKS like Py++ is trying to wrap the constructors of the 
protected inner class, which is obviously not going to work.
However, when I look in the generated code there's no wrappers for 
Outer::Inner, so the warning message's claim "Generated code will not 
compile." is misleading...
All the W1005 warnings I get might, however, still contain legimate ones 
that cause my compile problems. I'll need to dig further.

Regards,
Paul



The script:

#! /usr/bin/python
import os
import sys
import pygccxml
from pyplusplus import module_builder

mb = module_builder.module_builder_t(
        files=['all.h'],
        gccxml_path='/home/paul/local/bin/gccxml') #path to gccxml 
executable

mb.global_ns.include()

#Now it is the time to give a name to our module
mb.build_code_creator( module_name='doh' )

#I don't want absolute includes within code
mb.code_creator.user_defined_directories.append( os.path.abspath('.') )

#And finally we can write code to the disk
mb.write_module( os.path.join( os.path.abspath('.'), 'generated.cpp' ) )