Re: vardef with @# not working within context

[Aditya Mahajan <adityam@umich.edu>]

On Mon, 21 Sep 2009, Matthijs Kooijman wrote:

> Hi all,
>
> I've been fiddling around with metaobj a bit, but defining my own objects
> failed. After some debugging, I've reduced this to a metapost / context MkIV
> issue (so no metaobj specifics anymore).
>
> What happens, is that vardefs that use @# as a placeholder in their name only
> work when they are defined in an external .mp file. When I define them inside
> context (\startMPcode or \startMPinclusions), I get funny errors (mostly
> "Isolated expression", which seems to mean that the macro is not defined).
>
> I suspect this is because the way context extracts metapost code. Is this a
> fundamental problem, or could it be fixed?

You need to escape # inside any \startMPwhatever...\stopMPwhatever. This 
has to do with the fact that TeX processes the contents before they 
are passed to metapost, and TeX does not like isolated #. Try replacing
# with \# or \string#

Hans, does it make sense to parse all MP environments (ironically except 
\startMPenvironment, but that is almost redundant in MKIV) with a separate 
catcode regime where # has catcode other. After all, it is highly unlikely 
that anyone will define a TeX maco inside \startMPcode or 
\startMPinclusions.

Aditya
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