[NTG-context] How to make \def accept block or buffer as part of (long) command argument

[Benjamin Buchmuller]

Uff, this is indeed deep tex. Thanks a lot for the example, Hans! I still need to learn a lot.

After a walk and a bit of fresh air, I found another (much easier) way around my problem. This works since I don't need to deal with #2 in any special way:

\tolerant\def\startMyCommand[#1]%
{
\startallbeautifulcontextcommands
% whatever #1 does
}

\tolerant\def\stopMyCommand%
{
\stopallbeautifulcontextcommands
}

Then one can do in the main files:

\startMyCommand

\beginMyBuffer
bla bla
\endMyBuffer

\stopMycommand

> On Jan 2, 2022, at 14:43, Hans Hagen <j.hagen at xs4all.nl> wrote:
> 
> On 1/2/2022 2:14 PM, Benjamin Buchmuller wrote:
>> Thanks, Hans, for the answer, but I'm not sure if I get the point.
>> While this is possible in ConTeXt:
>> \startsection[title={My Title}]
>> \beginMyBlock
>> bla bla
>> \endMyBlock
>> \stopsection
>> The following won't work (end of file error):
>> \startMyCommand[optional={Maybe}]
>> \beginMyBlock
>> bla bla
>> \endMyBlock
>> \stopMyCommand
>> I had hoped for a simple command/modifier like \pleaseacceptblocks\def\startMyCommand[#1]#2\stopMyCommand to have #2 work in a similar way.
>> But maybe, as Wolfgang stated here (https://www.mail-archive.com/ntg-context@ntg.nl/msg73956.html), buffers and blocks can't be used in commands. (To add: Even when passed as arguments during compilation?)
> 
> You can bet that WS is right.
> 
> You really have to go dirty tex for this kind of magic:
> 
> \defineblock[MyBlock]
> \keepblocks[MyBlock]
> 
> \starttext
> 
> \tolerant\def\startMyCommand[#1]%
>  {\begingroup
>   \setcatcodetable\notcatcodes
>   \dostartMyCommand[#1]}
> 
> \let\stopMyCommand\relax
> 
> \normalexpanded{\def\noexpand\dostartMyCommand[#1]#2\expandtoken\notcatcodes92 stopMyCommand}%
>  {\endgroup
>   % whatever #1 does
>   \setbuffer[foo]#2\endbuffer
>   \typebuffer[foo]
>   \getbuffer[foo]}
> 
> or
> 
> \normalexpanded{\def\noexpand\dostartMyCommand[#1]#2\retokenized\notcatcodes {\stopMyCommand}}%
>  {\endgroup
>   % whatever #1 does
>   \setbuffer[foo]#2\endbuffer
>   \typebuffer[foo]
>   \getbuffer[foo]}
> 
> \startMyCommand[optional={Maybe}]
> 
> \beginMyBlock
> bla bla
> \endMyBlock
> 
> \stopMyCommand
> 
> \stoptext
> 
> and then of course further nesting mess ...
> 
> Hans
> 
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>                                          Hans Hagen | PRAGMA ADE
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