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From: Marco Pessotto <melmothx@gmail.com>
To: ntg-context@ntg.nl
Subject: Re: \do(single|double|etc)empty behaviour
Date: Thu, 16 Dec 2010 00:31:34 +0100	[thread overview]
Message-ID: <8762uuipex.fsf@universe.krase.net> (raw)
In-Reply-To: <37DA1975-1BCE-4922-A72E-4005474CC3CE@gmail.com>

Wolfgang Schuster <schuster.wolfgang@googlemail.com> writes:

> Am 15.12.2010 um 19:40 schrieb Marco Pessotto:
>
>> 
>> Hello there.
>> 
>> I was writing a small macro to emulate a custom \part command, and I
>> broke my head against \dosingleempty (but finally I won). 
>> 
>> […]
>> 
>> It's unclear to me how the arguments are passed between macros.
>> Probably it's just a matter of knowledge of TeX macro programming
>> (which obviously I don't have).
>
> Your test with \iffirstargument fails because you perform it after
> \startalignment which has itself a argument which sets
> \iffirstargument to true, a better way to check for content of the
> optional argument is \doifsomethingelse.
>
> \def\talpart
>   {\dosingleempty\dotalpart}
>
> \def\dotalpart[#1]#2%
>   {\page[right]
>    \blank[force,2*big]
>    \startalignment[center]
>    \doifsomethingelse{#1}
>      {{\bfc#1}\writetolist[talpart]{}{#1. #2}}
>      {\writetolist[talpart]{}{#2}}%
>    \blank[2*big]
>    {\bfd#2}
>    \stopalignment
>    \page[left]}
>
> Wolfgang
>

Thanks a lot for your explanation. I've added a "pitfalls" section to
http://wiki.contextgarden.net/Commands_with_optional_arguments#Pitfalls
(well, it was a pitfall at least for me)

-- 
Marco

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      reply	other threads:[~2010-12-15 23:31 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-12-15 18:40 Marco Pessotto
2010-12-15 22:56 ` Wolfgang Schuster
2010-12-15 23:31   ` Marco Pessotto [this message]

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