Re: [pygccxml-development] name_based_recognizer_t and pure functions

[Roman Y. <rom...@gm...>]

On Wed, Jan 13, 2010 at 3:01 PM, Berserker <ber...@ho...> wrote:
> I'm using name_based_recognizer_t to bind properties to my exposed methods.
> I don't understand why pure virtual (public) functions are not supported.
> Given the code:
>
> class Foo {
> public:
>     virtual std::string getName() const = 0;
>     virtual std::string getDescription() const;
> }
>
> Py++ creates the "Description" property but not the "Name" one.
> I tweaked the code in "property_recognizer_i.is_accessor" in this way:
>
> def is_accessor( self, mem_fun ):
>         if mem_fun.ignore:
>             return False
>         if mem_fun.access_type != 'public':
>             return False
>         if mem_fun.has_static:
>             return False
>         #if mem_fun.virtuality ==
> declarations.VIRTUALITY_TYPES.PURE_VIRTUAL:
>         #    return False
>         return True
>
> and now it seems working, can I ask the meaning of that check?

There are few reasons:
* In my opinion, "get" property is a function which returns
"reference". It is impossible to "override" pure virtual function,
which returns reference, on Python side and call it from C++. So I
filter such functions.

* This behavior is "close" to "native" Python:

class Foo:

    def __init__( self ):

        pass

    def x( self ):

        return 1

    x = property( x )



class DFoo(Foo):

    def __init__( self ):

        Foo.__init__(self)

    def x( self ):

        return 2



df = DFoo()

print df.x


The output is: <bound method DFoo.x of <__main__.DFoo instance at 0xb781758c>>

HTH

-- 
Roman Yakovenko
C++ Python language binding
http://www.language-binding.net/