Re: [PATCH 3/4] Implement cygw32

[Eli Zaretskii <eliz@gnu.org>]

> Date: Fri, 30 Dec 2011 01:36:03 -0800
> From: Daniel Colascione <dancol@dancol.org>
> CC: emacs-devel@gnu.org
> 
> ~/software/emacs/cyg.w32/lib-src
> $ ./emacsclient --eval '(window-system)'
> nil
> 
> ~/software/emacs/cyg.w32/lib-src
> $ ./emacsclient --eval 'window-system'
> nil
> 
> ~/software/emacs/cyg.w32/lib-src
> $ ./emacsclient --eval "(featurep 'w32)"
> t

Sorry, I don't see the relevance: daemon needs special handling
anyway.  E.g., featurep will be irrelevant if emacsclient is invoked
to create a text-mode frame.

> I agree that using window-system where appropriate is best.  That said,
> window-system isn't always appropriate.  It answers the question "what
> window system am I using right now?".  The featurep query answers "what
> window system is this copy of Emacs capable of using?".  Sometimes, the
> latter question is of greater interest.

But in an Emacs that is capable of creating _both_ w32 and X frames,
the values of (featurep 'x) and (featurep 'w32) are not mutually
exclusive.

If we don't want to go through the pains we went through when
multi-tty was introduced, we should never again add code that makes
assumptions about which window systems can or cannot coexist.