[Kde-bindings] possible conflicts in enums

[Richard Dale]

On Monday 07 September 2009 10:25:02 am Petr Vanek wrote:
> hi all,
> 
> we are facing some special problem here. Enums are handled as integers
> (numerical values) in our langugae bindings. Fair enough and easy to
> operate with it - except it's undeterministic in some cases:
> 
> Let's take for example these enums
> enum Qt::GlobalColor
> enum Qt::PenStyle
> 
> and available constructors (Qt):
> QPen ( Qt::PenStyle style )
> QPen ( const QColor & color )
> 
> If I use it in special case (pseudocode)
> 
> // "enum", but it's just an alias for 3
> foo = Qt::DotLine
> // then call
> pen = new QPen(foo)
> 
> so it's unclear which constructor to call. Just because Qt::DotLine
> equals Qt::white in this case.
> 
> Question: is there any way how to get a "enum type" from smoke? How to
> do it? We can create real enums for our language then.
> 
> If there is not such feature - can it be done? I mean: are you
> interested in it, or should we maintain it only in our codebase?
In QtRuby a Qt::Enum value is returned for enums. I don't think we need to add 
anything to smoke because converting from the long on the smoke stack to a 
Ruby Qt::Enum or whatever is needed for other languages, is something than a 
language specific marshaller can do. The enum 'MethodFlags' in smoke.h has a 
value mf_enum, and so it is easy to know if the method being called is 
returning an enum value, and the stack union ha an 's_enum' variant:

    enum MethodFlags {
        mf_static = 0x01,
        mf_const = 0x02,
        mf_copyctor = 0x04,  // Copy constructor
        mf_internal = 0x08,   // For internal use only
        mf_enum = 0x10,   // An enum value
        mf_ctor = 0x20,
        mf_dtor = 0x40,
        mf_protected = 0x80
    };

In QtRuby, marshall_basetypes.h this code does the conversion:

template <>
void marshall_to_ruby<SmokeEnumWrapper>(Marshall *m)
{
    long val = m->item().s_enum;
    *(m->var()) = rb_funcall(qt_internal_module, rb_intern("create_qenum"),
                             2, LONG2NUM(val), rb_str_new2( m->type().name()) 
);
}

-- Richard