On 12.04.2013 18:57, Greg Ercolano wrote:
> Albrecht> We're only calling const methods anyway, as x(), y(), window(),
> Albrecht> and this code is not subject to be changed in the future.
>
> Yes, though for some reason "as_window()" is not const,
> (it probably should be), which is why that cheat is necessary at the end
> there. Maybe using const_cast<Fl_Widget*>(w)->as_window() is better,
> which is what I decided to go with in top_window_offset().. will check.
Using const_cast<> is only another way to write it, but means the
same essentially, doesn't it? However, if some compilers wouldn't
flag a warning for const_cast<> but would for the old-style cast,
then we could maybe use it, but according to the CMP this shouldn't
be used for fltk 1.1 code, however it should be used for 2.0 code.
1.3 code is not (yet) specified, so we'd have to make a decision
about this first.
Concerning as_window(): ISTR that the first proposal was const, but
for some reason someone removed the const, but I'm not sure about it.
> Note in manolo's implementation, const is cast away at the top
> at the declaration of the variable, but I just switched it to const
> and cast const away only at the place where it was needed, at the
> as_window() call.
>
> So this does two things:
>
> 1) Keeps the variable const so one can't later add code like
> w->label("yoo hoo"); without getting an error..
> hey, it could be more subtle ;)
Yep, that's what I wrote with other words, isn't it? You cited it
above. I don't think that such a tiny method will ever be changed.
However, I'm not against your proposal, please go ahead...
> 2) Highlights exactly where the cheat is needed (at as_window())
> so if as_window() ever changes in the future to be const, it's
> easier to find and remove the const cast-away.
Fair point.
> Is there a reason as_window() and friends (other virtual
> implementations) are not const methods? Fl_Window::window() is.
You mean: "Fl_Window* Fl_Widget::window() const" is, right?
Other than what ISTR (see above), I don't know. Probably
"Fl_Window* Fl_Widget::window()" could be const as well, but
can we change it w/o breaking the ABI?
Albrecht
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