RE: About the :distant-foreground face attribute

[Drew Adams <drew.adams@oracle.com>]

> > What is the purpose of this face attribute, newly introduced for
> > 24.4?
> 
> Too lazy to read documentation?
> 
> "`:distant-foreground'
>      Alternative foreground color, a string.  This is like
>      `:foreground'
>      but the color is only used as a foreground when the background
>      color is near to the foreground that would have been used.
>      This is useful for example when marking text (i.e. the region
>      face).
>      If the text has a foreground that is visible with the region
>      face, that foreground is used.  If the foreground is near the
>      region face background, `:distant-foreground' is used instead
>      so the text is readable."

I see.  And just how does a user override this automatic "cleverness"?
How can a user really make her preference for the face take effect?

This kind of DWIMity should always allow users to take control back,
and preferably easily.  What you think might be best for all users
all the time might not be what some user thinks is best for herself.

And what about all of the existing code that tests :foreground or
otherwise expects it to reflect the actual foreground used?  Is that
code broken now, because Emacs substitutes a :distant-foreground
color behind its back?  Must all such code now change to test first
one and then the other?

When was this design OK'd (and why)?

> > First of all, the name :distant-foreground is not intuitive.  What
> > does "distant" mean in this context?
> 
> The same as in any other context, far removed from something else,
> i.e. the background.

I agree with Yidong about the name.  This is apparently a fallback,
alternative color, when (you) think the color specified by the
user or program is inappropriate.

> > Besides that, the implementation seems rather incomplete.  The
> > Customize interface, `modify-face', `face-spec-reset-face', and
> > other parts of Emacs haven't been updated for the existence of
> > this face attribute.
> 
> That is on purpose.  It is supposed to be automatically calculated.

So what?  All the more reason to bring it out into the open, so
users can know about it (and try to find some way to work around it,
if they like).

> > It's unclear what functions like `face-foreground' should now do
> > if there's a :distant-foreground.
> 
> No it is not.

Yes it is.  See above.  Search the distributed code and the Internet
for uses of "foreground" in Emacs Lisp code.  How much of that code
now needs to be modified to accommodate this gratuitous change.

Was there a real problem, reported by a real user, that this change
attempts to fix?  Or is this just someone's clever brainchild for
making Emacs smarter?

> > This all sounds like an invitation for more bugs.  In my opinion,
> > this feature is a bad idea.

+1

> All new features invite new bugs, so are you saying we should never
> add new features?

All new features should be proposed and discussed, before being cast
into the product.  That's my humble opinion.

> Your opinion is not very interesting, but if you have core for an
> alternative approach that would be interesting.

Why is any approach needed?  What is the (real) problem that needs
solving?