conditional argument and \doifemptyelse

conditional argument and \doifemptyelse

[Pablo Rodriguez]

Dear list,

I’m trying to define a command that has a conditional argument:

    \def\MyCommand#1#2#3{#1, #2, \doifemptyelse{#3}{#1}{#3}}
    \starttext
    \MyCommand{first}{second}
    \stoptext

The problem is that \doifemtpyelse only works if there the third
argument is there as {}. And the third argument is actually an exception
to workaround an unwanted behavior of the command in very few
exceptional cases.

Is there no way to make \MyCommand above work with \doifemptyelse even
if its third argument is not defined?

Many thanks for your help,


Pablo
-- 
http://www.ousia.tk
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Re: conditional argument and \doifemptyelse

[Wolfgang Schuster]

Am 06.11.2013 um 20:26 schrieb Pablo Rodriguez <oinos@gmx.es>:

> Dear list,
> 
> I’m trying to define a command that has a conditional argument:
> 
>    \def\MyCommand#1#2#3{#1, #2, \doifemptyelse{#3}{#1}{#3}}
>    \starttext
>    \MyCommand{first}{second}
>    \stoptext
> 
> The problem is that \doifemtpyelse only works if there the third
> argument is there as {}. And the third argument is actually an exception
> to workaround an unwanted behavior of the command in very few
> exceptional cases.
> 
> Is there no way to make \MyCommand above work with \doifemptyelse even
> if its third argument is not defined?

\def\MyCommand
  {\dotriplegroupempty\doMyCommand}
  
\def\doMyCommand#1#2#3%
  {#1, #2, \ifthirdargument #3\else #1\fi}

\starttext

\MyCommand{first}{second}{third}

\MyCommand{first}{second}

\stoptext

Wolfgang
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___________________________________________________________________________________

Re: conditional argument and \doifemptyelse

[Pablo Rodriguez]

On 11/06/2013 10:33 PM, Wolfgang Schuster wrote:
> Am 06.11.2013 um 20:26 schrieb Pablo Rodriguez <oinos@gmx.es>:
>> [...]
>> Is there no way to make \MyCommand above work with \doifemptyelse even
>> if its third argument is not defined?
> 
> \def\MyCommand
>   {\dotriplegroupempty\doMyCommand}
>   
> \def\doMyCommand#1#2#3%
>   {#1, #2, \ifthirdargument #3\else #1\fi}
> 
> \starttext
> 
> \MyCommand{first}{second}{third}
> 
> \MyCommand{first}{second}
> 
> \stoptext

Wolfgang,

many thanks for your reply and the fix.


Pablo
-- 
http://www.ousia.tk
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maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context
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