Re: [gtkmm] gtkmm 2.4 questions
- From: Frank Naumann <fnaumann cs uni-magdeburg de>
- To: Matthew Walton <matthew alledora co uk>
- Cc: gtkmm-list gnome org
- Subject: Re: [gtkmm] gtkmm 2.4 questions
- Date: Wed, 16 Jun 2004 18:03:29 +0200 (CEST)
Hello!
I would be surprised if the recomputation you are doing requires a change in
the underlying data or the fundamental state of the CellRenderer; therefore
you should be able to do it inside a const method without a great deal of
difficulty, perhaps with the help of a few mutable data members (perhaps for
result caching where appropriate).
Yes, mainly the result is cached for the immediatly following render call.
Ok, having the cache result mutable don't look so bad.
It seems a good rule of API design to write methods as const whenever you
possibly can. This provides a clear and guarenteed interface to the user,
helping them to write code that doesn't have unexpected side effects. That
might be the Haskell programmer in me speaking.
Yes, I do so too for my own code.
Then my question, why is get_size_vfunc const? What's the difference
compared to render_vfunc for example?
I can't answer that question, as I had no input on the design of the API
there. I would have expected render_vfunc to be const, but it may operate in
a way which surprises me and forces it to be non-const.
render_vfunc should be const too, then I aggree on the logic :-) Otherwise
something is not consequent and logical.
Regards,
Frank
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