Pass optional empty arguments in a newcommand down to another command with optional empty arguments in LaTeX

macrosoptional arguments

I would like to define a newcommand with two optional arguments, which in turn, calls on another command with two optional arguments.

Something like the following (\B calls \A). How do I do it?

\newcommand{A}[3][][]{{#1 + #2 + #3}}
\newcommand{B}[3][][]{#1 + \A[#2][#3]{#1}}

\B{9}
\B[1][]{9}
\B[][3]{9}
\B[1][3]{9}

EDIT

I tried to give a similar MWE, but I am afraid that the above example actually may not properly convey exactly what I need.

The reason I had this question is to create a command that takes in a certain bib-item and highlights it. I would like to pass two optional arguments to \parencite[pre][post]{#1} (where pre and post could be empty) via a newcommand \hlcite[pre][post]{#1}. The command \hlcite would then highlight the references.

\usepackage{graphicx, color}
\usepackage[dvipsnames]{xcolor}
\usepackage{bookmark}
\usepackage[
    backend=biber,          % backend: biber
    style=authoryear,       % style: numeric-comp, authoryear
    sorting=ynt,            % sorting: none, ynt
]{biblatex}
\usepackage{soul} 
\newcommand{\hlc}[2][yellow]{\sethlcolor{#1} \hl{#2}}

%% This works
\newcommand{\hlcite}[1]{\colorbox[green]{\mbox{\parencite{#1}}}}

%% But this throws error
\newcommand{\hlcite}[3]{\hlc[green]{\mbox{\parencite[#2][#3]{#1}}}}

References

Adding optional arguments

Non-stackoverflow/stackexchange links:

Using if conditional in latex:

References to use \mbox with \cite or \parencite inside \newcommand for highlighting.

Highlighting text in Latex:

Best Answer

You can use \NewDocumentCommand.

\NewDocumentCommand{\hlc}{O{yellow}m}{\sethlcolor{#1}\hl{#2}}

\NewDocumentCommand{\hlcite}{oom}{%
  \hlc[green]{%
    \IfNoValueTF{#1}{% no optional argument
      \parencite{#3}%
    }{%
      \IfNoValueTF{#2}{% just one optional argument
        \parencite[#1]{#3}%
      }{% both optional arguments
        \parencite[#1][#2]{#3}%
      }%
    }%
  }% end of \hlc
}

Note that you don't want a space between \sethlcolor{#1} ad \hl{#2}.

Related Solutions

[Tex/LaTex] How to pass optional arguments to command

If a macro argument is supposed to be a set of key-value pairs, making use of standard packages to the purpose (keyval, xkeyval and others), it is generally harmless to pass it the empty list.

\newcommand{\foo}[2][]{%
  <actions to be performed before>%
  \VerbatimInput[#1]{#2}%
  <actions to be performed after>%
}

is the method you're looking for, because fancyvrb does use keyval.

Pass 3 optional arguments in newcommand

I see two ways to do it.

With xparse you can use \NewDocumentCommand to create a new command with multiple optional arguments. Once you get beyond two optional arguments the usage becomes a bit clumsy and a key-value interface may be the better solution. The clumsiness is because with three consecutive optional arguments, if you only want to specify the third you must also specify the first and second. If you only want to specify the second you must also specify the first. Otherwise, there is no way to know which of the three optional arguments you are specifying.

MWE using xparse:

\documentclass{article}
\usepackage{xparse} % Automatically included in recent LaTeX releases;
                    % load manually as here for older releases.

\NewDocumentCommand{\Sc}{ O{x} O{q} O{a} }{%
  S(#1; #2, #3)
}%

\begin{document}
\Sc

\Sc[w][y][z] % change all three arguments

\Sc[m]       % change only the first argument

\Sc[x][m]    % change only the second argument

\Sc[x][q][m] % change only the third argument
\end{document}

Another way to do it is to use the xargs package, which provides the \newcommandx macro which, in turn, also lets you specify optional arguments with default values but the syntax and usage is a bit different. You don't explicitly have to supply the default value for, say, the first two arguments if all you want to change is the third argument, but you still must specify empty placeholder delimiters for the missing arguments.

MWE using xargs:

\documentclass{article}
\usepackage{xargs}

\newcommandx*{\Sc}[3][1=x,2=q,3=a,usedefault]{%
  S(#1; #2, #3)
}%

\begin{document}
\Sc

\Sc[w][y][z] % change all three arguments

\Sc[m]       % change only the first argument

\Sc[][m]     % change only the second argument

\Sc[][][m]   % change only the third argument
\end{document}

There may be other more elegant solutions. With three consecutive optional arguments, you need to be careful about what may happen if the user omits any of the arguments.

References

Best Answer

Related Solutions

[Tex/LaTex] How to pass optional arguments to command

Pass 3 optional arguments in newcommand

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