Re: Proposal: window-system-version function

[Dmitry Antipov]

On 05/21/2012 08:20 PM, Eli Zaretskii wrote:

> Thanks.  However, this change breaks backward compatibility.  Perhaps
> it would be better to leave the variable alone, and _add_ the
> function; that would be backward-compatible.

I fixed Lisp code in lisp/international/mule-diag.el and
lisp/textmodes/artist.el; not sure about external packages which
may also use it.

Leaving the variable "as is" means that window-system-version
and (window-system-version) may have different values, which
is confusing. Ideally, window-system-version should be a frame-local
variable, but I'm wondering whether this is possible in Emacs.

> > +It's value is a number:
> > + - 0 for a termcap frame,
> > + - Major X protocol version for the frame on X display,
> > + - Major OS version for the frame on MS-Windows display,
> > + - 24 for the frame on direct-write MS-DOS display,
> > + - 10 for the frame on a GNUstep or Macintosh Cocoa display.
>
> This is inaccurate at least for MS-DOS and MS-Windows.  Do we really
> want to document the precise meaning of the values here?  Why is that
> important?

I'm not sure about exact values on a systems beyond *nix, and I suppose
that every Lisp-visible function should be documented.

> > +#ifdef HAVE_X_WINDOWS
> > +    case output_x_window:
> > +      return make_number (ProtocolVersion (FRAME_X_DISPLAY (f)));
> > +#endif
> > +#ifdef WINDOWSNT
> > +    case output_w32:
> > +      return make_number (w32_major_version);
> > +#endif
> > +#ifdef MSDOS
> > +    case output_msdos_raw:
> > +      return make_number (24);
> > +#endif
>
> The MSDOS build supports HAVE_X_WINDOWS as well, so HAVE_X_WINDOWS and
> MSDOS are not by themselves mutually exclusive.

The cpp stuff above has no mutually exclusive paths (no #elif or so),
so it should work if both HAVE_X_WINDOWS and MSDOS are defined.

Dmitry