Re: Fwd: GTK+ is real object oriented?

[David Nečas <yeti physics muni cz>]

On Sun, Dec 20, 2009 at 05:26:20PM -0200, frederico schardong wrote:
> Yes, C don't provide sintax support for do my example of method.
> 
> In OOP such class must have self methods to set self attributes.
> 
> What happen is GObject (by the C limitation) just have attributes, the
> methods to set its attributes are functions out of the struct. Ok, is
> this what happen, but for this facts don't broke the OOP?

You have a weird definition of OO.

Smalltalk people could tell you that calling methods is fake OO because
to do real OO you must send messages to objects.  Now what?

To the syntax issue.  In fact, virtual methods in Gtk+ are called

GTK_WIDGET_GET_CLASS(widget)->show(widget)

where GTK_WIDGET_GET_CLASS explicitly obtains the virtual table
(referenced from within the object struct) because the compiler won't do
it for you and then you can call the method.

But as everyone else prefers a sane syntax to a cozy objectishy feeling,
this is wrapped with something like gtk_widget_show() for virtual
methods and non-virtual methods look entirely like functions.

If it matters to you whether calling methods looks like

    object.method(arg1, arg2)
    object_method(arg1, arg2)
    (object method arg1 arg2)
    method { arg1 } { arg2 } : object

then Gtk+ is fake OO by your definition but hardly anyone cares.

If it matters to you in what bit of memory methods are physically
stored, then check if Smalltalk, Ocaml, Haskel, etc. are OO according to
your definition or not.  Hopefully you are aware the methods are seldom
actually stored in `the object struct' even though they are placed there
in the source code of e.g. C++ because that would be a collosal waste of
resources.

If you are troubled by the fact that one can write gtk_widget_frobnicate()
that will look exactly like a GtkWidget method but would not be, then
you simply noticed one of the things that cannot be enforced in C.  The
rule is that you must not name functions gtk_widget_frobnicate().

The object file compiled from gtkwidget.c then lists all the GtkWidget
methods and is as good table of methods of the object as anything else.

Yeti