Thanx Henri for answer.
Maybe I have been explaining wrong my problem. I would need a variant without a parameter and concurrently without braces. Command without braces swallows the break of the paragraph.
\def\Command#1%
{\expdoifelse{#1}{}{100}{#1}}
\starttext
1. \Command{5} % OK
2. \Command % OK
3. As You see, Command without braces swallows the break of the paragraph.
1. \dorecurse{\Command{5}}{\recurselevel\crlf} % not working
2. \dorecurse{\Command{}}{\recurselevel\crlf} % not working
\stoptext
Jaroslav Hajtmar
Dne 27.06.17 13:05, ntg-context za uživatele Henri Menke napsal(a):
On Tue, 2017-06-27 at 08:58 +0000, Jaroslav Hajtmar wrote:
> Hello ConTeXist.
> I'm not able to solve a macros problem with one optional argument. I need the macro to return a
> value that can be used as a dorecurse loop parameter.
> Is there possibility create macro with optional parameter and parameter is concurrently inside in
> braces? (in nonsquare brackets)?
> I've tried to experiment with examples from the wiki, but I'm not clear about it.
>
> Thanx for help.
> Jaroslav Hajtmar
>
> Here is minimal example:
>
> \def\DoCommand[#1]%
> {\iffirstargument#1\else100\fi}
>
> \def\Command%
> {\dosingleargument\DoCommand}
>
> %\def\DoAnotherCommand{#1}%
> % {\iffirstargument#1\else100\fi}
>
> %\def\AnotherCommand%
> % {\dosingleargument\DoAnotherCommand}
>
> \starttext
>
> 1. \Command[5] % OK
>
> 2. \Command % OK
>
>
>
>
> %1. \dorecurse{\Command[5]}{\recurselevel\crlf} % not working
>
> %2. \dorecurse{\Command}{\recurselevel\crlf} % not working
The first argument to \dorecurse has to expand to a number. Therefore it has to be fully-
expandable. Scanning for optional brackets is never expandable. You have to do it this way:
\def\Command#1%
{\expdoifelse{#1}{}{100}{#1}}
\starttext
1. \Command{5} % OK
2. \Command{} % OK
1. \dorecurse{\Command{5}}{\recurselevel\crlf} % not working
2. \dorecurse{\Command{}}{\recurselevel\crlf} % not working
\stoptext
> \stoptext
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