General ⇒ Conditional Branch in new Command

[parnmatt]

Hi, I was wondering if anyone can suggest a way to get \ifthenelse working within another command.

This segment is what I have at the moment, granted I know it doesn't work, but it should give you an idea what I mean.

Code: Select all

\usepackage{xifthen}
\usepackage{minted}

\newcommand{\codesrc}[5][]{%
	\inputminted[%
		\ifthenelse{\isempty{#1}}{}{label=#1,}%
		frame=lines,%
		framesep=1.2em,%
		linenos=true,%
		\ifthenelse{\isempty{#2}}{}{firstnumber=#2,firstline=#2,}{}%
		\ifthenelse{\isempty{#3}}{}{lastline=#3,}{}%
	]{#4}{#5}%
}

I've thought perhaps trying to add to a string str = str + "new code" if that's even possible, and to then execute that string as LaTeX code, though I don't know how to do it …if it's even possible.

OK, those are the two possible ideas I have. If anyone has any constructive advice or ideas on this, please comment.

[josephwright]

You are trying to use a 'functional' approach, which is not how TeX works. The usual approach to this sort of problem is to create the input you want using \edef. However, \ifthenelse is not 'expandable' and this will not work. Instead, I would use the so-called 'e-TeX extensions', which are automatically available in any modern LaTeX

Code: Select all

\makeatetter
\newcommand{\codesrc}[5][]{%
  \begingroup
  \edef\@tempa{%
    \endgroup
    \noexpand\inputminted[%
      \expandafter\ifx\expandafter A\detokenize{\@gobble #1?}A%
      \else
        label=\unexpanded{#1},%
      \fi
      frame=lines,%
      framesep=1.2em,%
      linenos=true,%
      \expandafter\ifx\expandafter A\detokenize{\@gobble #2?}A%
      \else
        firstnumber=\unexpanded{#2},firstline=\unexpanded{#2},%
      \fi
      \expandafter\ifx\expandafter A\detokenize{\@gobble #3?}A%
      \else
        lastline=\unexpanded{#3}%
      \fi
    ]%
  }%
  \@tempa{#4}{#5}%
}
\makeatother

The idea here is that we construct \@tempa to contain what you would have typed in if you'd done this directly. Then we use that to execute the command you want.