[NTG-context] How to let a macro check the previous value of #1 the last time the same macro was called?

Aditya Mahajan adityam at umich.edu
Tue Jan 11 05:22:06 CET 2022


On Tue, 11 Jan 2022, Henning Hraban Ramm via ntg-context wrote:

> Am 10.01.22 um 20:21 schrieb Wolfgang Schuster:
> > Henning Hraban Ramm via ntg-context schrieb am 10.01.2022 um 09:52:
> >> Would it make more sense, or would it be “cleaner” to use a variable?
> > 
> > You can get rid of the temp variable before the command definition but 
> > now you have to access it with a different method in \mymacro, below is 
> > one way (LMTX only) but \setvariable and \getvariable work as well.
> > 
> > \define[1]\mymacro
> >    {\iftok{#1}{\getvalue{previousmymacro}}%
> >       same as last time
> >     \else
> >       it is different from last time
> >     \fi
> >     \setvalue{previousmymacro}{#1}}
> 
> That was the approach that I meant. Thank you.
> 
> But would you consider one way to be better?

Just for fun: lua code

\startluacode
  local previous = nil

  interfaces.implement {
    name = "mymacro",
    public = true, 
    arguments = "string",
    actions = function (current) 
          if current == previous then
              context("same as last time")
          else
              context("Different!")
          end
          previous = current
      end,
  }

\stopluacode

\starttext

\startlines
cat: \mymacro{cat}
cat: \mymacro{cat}
mouse: \mymacro{mouse}
mouse: \mymacro{mouse}
cat: \mymacro{cat}
\stoplines

\stoptext

Aditya


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