[metapost] Bug? Parsing def := := enddef;
taco at elvenkind.com
Thu Jan 21 10:18:14 CET 2010
> In article <4B57FF3D.30800 at elvenkind.com>,
> Taco Hoekwater <taco at elvenkind.com> wrote:
>> Nicola wrote:
>>> But the following gives an error:
>>> This is MetaPost, version 1.208 (kpathsea version 3.5.7dev)
>>> *def := := enddef;
>>> ! Missing `=' has been inserted.
>>> <to be read again>
>>> <*> def := :=
>>> That looks like a small bug. Taco, can you confirm?
>> Confirmed. Whether this is a 'fixable' bug remains to be seen,
>> I will investigate.
> Actually, I've noticed that both
> def := = enddef;
> def = := enddef;
> are ok (and similarly for vardef). The sense may be: if you are
> redefining ':=' you are not allowed to use it in the definition header
> itself (and similarly for '='), for the simple reason that you are
> changing its meaning. So, I think this is actually expected behaviour.
> Really, in The METAFONTbook, := is never used in a macro header, so this
> might be the only reason why it exists (to allow the user to redefine =)!
Stefan, if you are reading this, can you add a note to this effect to
The solution for plain 'def' is pretty straightforward, but the one
for 'vardef' would be quite ugly, so I'd rather not patch the executable
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