Re: delwin() and deleting windows with subwindows

[Thomas Dickey]

On Thu, Aug 11, 2022 at 12:35:49PM -0400, Bill Gray wrote:
> On 8/10/22 20:08, Thomas Dickey wrote:
> > it depends: in the SVr4 code, child-windows have a link to their parent,
> > using that to maintain a reference count -- and tell it if there are no
> > remaining children, and return an error if any remain.  But that's not
> > enough to just delete all of the children and the parent window, which
> > would make it nice(r) for applications.
> 
>    Well,  yes... nicer,  and apparently we _should_ recursively delete to
> follow the XSI Curses standard ("It [delwin] must delete subwindows before
> deleting their parent.")

It's arguably ambiguous: others read that as saying that delwin can't
touch the parent until the subwindows have been (by whatever means)
deleted.
 
>    The only downside I see to recursive deletion would be if you did the
> following :
> 
>    WINDOW *win = newwin( ...);
>    WINDOW *sub = subwin( win, ...);
> 
>    delwin( win);
>    access something in sub;
> 
>    At present,  the delwin() call would fail in ncurses and SVr4.  In
> PDCurses and Solaris X/Open curses,  win would be deleted and sub wouldn't.
> In either case,  attempts to access something in sub will still work.

portability's a problem :-)

-- 
Thomas E. Dickey <dickey@invisible-island.net>
https://invisible-island.net
ftp://ftp.invisible-island.net

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