Re: [pygccxml-development] Two patches proposal

[Berserker <ber...@ho...>]

> The short answer is no :-(. The main reason for it: such code does not
> meat user expectations. Let me explain:
> 
> foo = Foo()
> foo.Bar.x = 2
> assert foo.Bar.x == 2
> 
> The following is explanation how I thought "add_properties"
> functionality should be used in such case.
> 
> class custom_name_based_recognizer_t( name_based_recognizer_t ):
>     def __init__( ... ): ...
> 
>     def check_type_compatibility(self, fget, fset):
>          <your code >
> 
> cls = mb.class_( ... )
> cls.add_properties( recognizer=custom_name_based_recognizer_t() )
> 
> Could it be an acceptable solution?


Yes, I'm actually using that solution. I'm sad about "user expectations" but what 
about this case then (without the patch):

foo = Foo()
b1 = foo.Bar
b1.x = 2
b2 = foo.Bar

b2.x = ?

I think that this is another case where we can discuss about "user expectations", what about?


> I am not sure. According to the MSDN (
> http://msdn2.microsoft.com/en-us/library/h1y7x448.aspx ) "...C++
> constructors that have just one parameter automatically perform
> implicit type conversion. ...". In your case the constructor has 2
> arguments. I tested the following code with gcc 4.4.1
> 
> struct Foo{
>     Foo( int i, bool b=false ){}
> };
> 
> void dosmth( Foo ){
> }
> 
> int main( int argc, const char* argv[] ){
>     dosmth( 11 );
> };
> 
> and it compiles fine.
> 
> I don't know C++ at the level of standard. Do you know what the
> standard says? Does the code compile fines with MSVC compiler?
> 
> > How can I write it?
> 
> It is not a problem to write it:
> 
> if 1 != len( self.required_args ):
>     return False
> 
> > Any hope to apply the code to the svn?
> 
> The first issue - I believe you have a solution, the second one - I
> prefer to know the answers. If they are positive - I will apply the
> patch almost immediately.


I'm not a "standard expert" too, but I can confirm that your code does compile 
on MSVC (tested on VC2005 and VC2008).
Actually I "tweaked" the method in this way (probably it could be written better...):


def override_does_define_implicit_conversion(self):
    if self.parent.is_abstract:
        return False

    if self.is_copy_constructor:
        return False   
   
    args = len(self.arguments)
    if args != 1:
        if args > 1:
            for arg in self.arguments[1::]:
                if not arg.default_value:
                    return False
        else:
            return False
    
    if self.parent.find_out_member_access_type(self) != declarations.ACCESS_TYPES.PUBLIC:
        return False
        
    return True
    
decl_wrappers.calldef_wrapper.constructor_t.does_define_implicit_conversion = override_does_define_implicit_conversion


It works but as you probably know I don't like this solution :)

Thanks for your help as usual ;)

 		 	   		  
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