Re: Issue 3498: fatal error with toplevel-markup-identifier (issue 12945043)

[David Kastrup]

Janek Warchoł <address@hidden> writes:

> 2013/8/18  <address@hidden>:
>> On 2013/08/18 10:20:07, janek wrote:
>>> Sorry for a possibly ignorant question: will this patch also remove
>>> the error in case of
>>> mus = { a }
>>> \mus
>>> ?
>>
>> No.
>>
>>> If not, would there be an easy way to fix that?
>>
>> Well, we could delete all functionality of \addlyrics etc
>> (Ok, was a joke)
>
> Ah, i see the difficulty now, thanks!


It's not entirely clear since you can't write

mus = \addlyrics ...

anyway.  The main problem is that \mus differs from #mus in that it
needs to be evaluated _before_ a token can be handed to the parser.
This will only change once every \xxx has the same token category.  The
project of reducing the number of xxx_IDENTIFIER tokens is ongoing (and
has created quite a few more possibilities) but by far not finished.

If \mus returned _two_ tokens, the first without actually evaluating
mus, it is conceivable that the first token already provides enough
information to the parser to know that \addlyrics (and a few similar
commands) are definitely _not_ coming, so that it can evaluate the
assignment before evaluating \mus itself.

But that would be a rather complex change for comparatively little
benefit.  So I prefer focusing on reducing the xxx_IDENTIFIER cases
instead.

-- 
David Kastrup