x-font-family-list

x-font-family-list

[Eli Zaretskii]

I don't understand this change:

> 	* xfaces.c (Fx_font_family_list): Function deleted.  Compatibility
> 	version moved to faces.el.

Here's the compatibility function:

> +(defun x-font-family-list (&optional frame)
> +  "Return a list of available font families on FRAME.
> +If FRAME is omitted or nil, use the selected frame.
> +Value is a list of conses (FAMILY . FIXED-P) where FAMILY
> +is a font family, and FIXED-P is non-nil if fonts of that family
> +are fixed-pitch."
> +  (if (fboundp 'font-family-list)
> +      (mapcar (lambda (family) (cons family nil))
> +	      (font-family-list))
> +    '(("default" . t))))
> +(make-obsolete 'x-font-family-list 'font-family-list "23.1")

This "compatibility version" is not compatible, AFAICS: it claims that
none of the font families are fixed-pitch, and also assumes that some
builds of Emacs don't have font-family-list fboundp, which is never
true AFAIK.  The net effect is that in the --without-x and MS-DOS
builds x-font-family-list now returns nil, whereas previously it was
unbound in the --without-x build and on MS-DOS returned `("default" . t)'.

What am I missing?  What was the purpose of this change?

If the value of this function is not important at all, let's delete it
completely.  If it _is_ important, then let's make the replacement
really compatible, which means at the very least make the cdr of the
cons cells it returns be non-nil for fixed-pitch font families.

Re: x-font-family-list

[Chong Yidong]

Eli Zaretskii <eliz@gnu.org> writes:

> I don't understand this change:
>
>> 	* xfaces.c (Fx_font_family_list): Function deleted.  Compatibility
>> 	version moved to faces.el.
>
> This "compatibility version" is not compatible, AFAICS: it claims that
> none of the font families are fixed-pitch, and also assumes that some
> builds of Emacs don't have font-family-list fboundp, which is never
> true AFAIK.  The net effect is that in the --without-x and MS-DOS
> builds x-font-family-list now returns nil, whereas previously it was
> unbound in the --without-x build and on MS-DOS returned `("default" . t)'.
>
> What am I missing?  What was the purpose of this change?

The previous version of x-font-family-list (in xfaces.c) was broken---it
simply returned the return value of font-family-list, and so did not do
what the docstring said.  I noticed that when updating the font handling
documentation, so I made this change, but forgot to implement the
fixed-p part.  Thanks for spotting the omission

> If the value of this function is not important at all, let's delete it
> completely.  If it _is_ important, then let's make the replacement
> really compatible, which means at the very least make the cdr of the
> cons cells it returns be non-nil for fixed-pitch font families.

I don't think it's important, but am not sure whether there is any
external code relying on it.  Normally, this means that we should try to
change the compatibility function and make it compatible.  But, I don't
know a simple way of computing whether a font is fixed-pitch using the
new font code, without jumping through some ugly hoops (e.g., somehow
turning each family name into an xlfd and examining its "monospace"
entry).  If no one can suggest a good method, let's just delete the
function.

Re: x-font-family-list

[Leo]

On 2009-01-09 20:32 +0000, Chong Yidong wrote:
> I don't think it's important, but am not sure whether there is any
> external code relying on it.

Maybe that function can be deleted. It is not a user level function, so
all the users we care about will remain happy. Any maintained packages
will evolve as Emacs evolves slowly.

Best,
-- 
.:  Leo  :.  [ sdl.web AT gmail.com ]  .: I use Emacs :.

Re: x-font-family-list

[Eli Zaretskii]

> From: Chong Yidong <cyd@stupidchicken.com>
> Cc: emacs-devel@gnu.org
> Date: Fri, 09 Jan 2009 15:32:52 -0500
> 
> I don't think it's important, but am not sure whether there is any
> external code relying on it.  Normally, this means that we should try to
> change the compatibility function and make it compatible.  But, I don't
> know a simple way of computing whether a font is fixed-pitch using the
> new font code, without jumping through some ugly hoops (e.g., somehow
> turning each family name into an xlfd and examining its "monospace"
> entry).  If no one can suggest a good method, let's just delete the
> function.

Either delete it entirely, or make it signal an error.

Re: x-font-family-list

[Chong Yidong]

Eli Zaretskii <eliz@gnu.org> writes:

>> I don't think it's important, but am not sure whether there is any
>> external code relying on it.  Normally, this means that we should try to
>> change the compatibility function and make it compatible.  But, I don't
>> know a simple way of computing whether a font is fixed-pitch using the
>> new font code, without jumping through some ugly hoops (e.g., somehow
>> turning each family name into an xlfd and examining its "monospace"
>> entry).  If no one can suggest a good method, let's just delete the
>> function.
>
> Either delete it entirely, or make it signal an error.

I've removed it from CVS.

Re: x-font-family-list

[Eli Zaretskii]

> From: Chong Yidong <cyd@stupidchicken.com>
> Cc: emacs-devel@gnu.org
> Date: Sat, 10 Jan 2009 07:58:37 -0500
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> >> I don't think it's important, but am not sure whether there is any
> >> external code relying on it.  Normally, this means that we should try to
> >> change the compatibility function and make it compatible.  But, I don't
> >> know a simple way of computing whether a font is fixed-pitch using the
> >> new font code, without jumping through some ugly hoops (e.g., somehow
> >> turning each family name into an xlfd and examining its "monospace"
> >> entry).  If no one can suggest a good method, let's just delete the
> >> function.
> >
> > Either delete it entirely, or make it signal an error.
> 
> I've removed it from CVS.

Thanks.

Re: x-font-family-list

[Eli Zaretskii]

> From: Chong Yidong <cyd@stupidchicken.com>
> Date: Sat, 10 Jan 2009 07:58:37 -0500
> Cc: emacs-devel@gnu.org
> 
> I've removed it from CVS.

Btw, do we need font-family-list to return something non-nil on TTY
frames?

Re: x-font-family-list

[Jason Rumney]

Eli Zaretskii wrote:
> Btw, do we need font-family-list to return something non-nil on TTY
> frames?
>   

I wouldn't think so, TTY frames don't have any fonts so they should 
return nil.

Re: x-font-family-list

[Eli Zaretskii]

> Date: Sun, 11 Jan 2009 00:08:37 +0800
> From: Jason Rumney <jasonr@gnu.org>
> CC: Chong Yidong <cyd@stupidchicken.com>, emacs-devel@gnu.org
> 
> Eli Zaretskii wrote:
> > Btw, do we need font-family-list to return something non-nil on TTY
> > frames?
> >   
> 
> I wouldn't think so, TTY frames don't have any fonts so they should 
> return nil.

Every frame has at least one font: the one it uses to display the
text.

The question is: would some Lisp code call font-family-list expecting
it to always return something non-nil.  Since in Emacs 23 GUI frames
and TTY frames can be found in the same session, I'm not sure what is
the right answer to that.