Frank wrote:
>LaTeX already does have this feature if you think about, part of the font
>selection mechanism was done explicitly to provide this
If you're simply saying that the information is stored somewhere then yes,
that's exactly why I do not think it would be that difficult to implement.
If you're saying that I can do something like my examples of
\UseTextSymbolIFE without first having to define a dozen or so helper
macros then you've lost me completely.

> > One example of how to use them is to make a command that typesets some
> > symbol if that symbol is available and which typesets some fake of it
> > otherwise.
> > [...]
>what's wrong with using the \DeclareTextSymbolDefault (and friends) for that
>purpose? that is exactly doing what you ask for as far as i can see.
There is nothing wrong with using them, but my intention here was to give
an example of how it could be used by an author (perhaps I should have
written \newcommand instead of \DeclareRobustCommand to make my intentions

>eg instead of
> >   \DeclareRobustCommand\euro{%
> >      \UseTextSymbolIFE{TS1}{\texteuro}{EUR}%
> >   }
>you could
> \DeclareTextCommandDefault\texteuro{some definition}
>and then your statement:
> >
> > to get a \euro command that gives something understandable regardless of
> > whether it is typeset on a site with or without a TS1 encoded symbol font.
>holds as well.
The question is of course what the "some definition" should be. If I take
it to be EUR, it may well not the best thing available. If I take it to be
\UseTextSymbol{TS1}{\texteuro}, then people who do not have a TS1 font
available won't get it. By using the test in \UseTestSymbolIFE, I define a
macro which can behave more intelligently. But it seems you acknowledged

>the catch is that this works best if TS1 is something that is either there
>(for all fonts) or not there at all. if it is there only for a small fraction
>of the fonts then the scheme using Defaults works less good than the proposed
>I'm not saying that the proposed test commands for certain font
>characteristics aren't worth having, but i think they should not be used to
>handle something like \textdegree or \texteuro on a large scale. The amount of
>processing etc would be extremely high

Would it? I cannot say I understand all the inner workings of NFSS, but I
have the impression that there is one control sequence which can be tested
to see if the font have been loaded or declared and one control sequence
which can be tested to see if a font definition file has been loaded. This
would mean that after the first time the availability of a specific font
has been tested, additional tests can be completed in two ifs (either "yes,
the font is available" or "no, the font has not been loaded, and no, it is
not because I haven't loaded the font definition file yet, so therefore the
font is not availavle"). That's nothing compared to what is done during a
simple font change.

>and i think this is fixing the symptoms
>of a (one of the) problem(s) with NFSS2 instead of providing the right basic
>interfaces for that problem.
>In my opinion it is time to start thinking about the errors and problems with
>the NFSS2 approach and start experiments for developing NFSS3 but the first
>step for doing this should be via experimental packages that one has to load
>in the document somehow (ie either in a class file or in the preamble)

That's fine by me, I'm in no hurry in this matter. BTW, is the writing of
such packages a privilege for the LaTeX3 project team, or may the public
contribute as well?

Lars Hellström