On 5/24/2018 11:21 AM, Christoph Reller wrote:
On Wed, 23 May 2018 16:01:05 +0200, Hans Hagen <j.ha...@xs4all.nl> wrote:
On 5/23/2018 3:39 PM, Christoph Reller wrote:
Hi,
What is the right way to define a command with both mandatory and
optional arguments, e.g:
\MyCommand[optional][mandatory]
Consider the following MWE:
\unexpanded\def\MyCommand[#1]{
\dosingleempty{\doMyCommand[#1]}}
\def\doMyCommand[#1][#2]{
\doifsomething{#1}{number 1: #1\par}
\doifsomething{#2}{number 2: #2}\blank[big]}
\starttext
\MyCommand[A][B]
\MyCommand[A]
\stoptext
In last year's versions of ConTeXt the output was
number 1: A
number 2: B
number 1: A
In the latest version of ConTeXt the output is
number 1: A
number 2: B
number 2: A
Is this behavior intended? How can I make a definition whose behavior
does not change in new versions of ConTeXt?
i'm not sure wht happens at your end but this is the best way:
\unexpanded\def\MyCommand
{\dodoubleempty\doMyCommand}
\def\doMyCommand[#1][#2]%
{\iffirstargument
number 1: #1%
\par
\fi
\ifsecondargument
number 2: #2%
\fi
\blank[big]}
\starttext
\MyCommand[A][B]
\MyCommand[A]
\stoptext
Thank you Hans for this information. My question is rather about error
handling. I want:
\MyCommand[A][B] % <- succeeds with #1->A, #2->B
\MyCommand[A] % <- succeeds with #1->A
\MyCommand % <- fails with "! Use of \MyCommand doesn't match its definition"
I just wanted to ask whether there is a standard way to achieve this
with \do<whatever>empty. If not, then this is also okay.
just use \dodoubleempty instead
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Hans Hagen | PRAGMA ADE
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