Finding minimum and maximum values of arguments in function

Question

I am defining a \newcommand called \eventsperiodslist which call some other commands: \event[]{Digits}{} and \period[]{Digits}{Digits}{}

The arguments called "Digits" in \event and \period contains digits that I am trying to extract to find the minimum and maximum values of all numbers within \eventsperiodslist.

I do not know where to start:

• With a \foreach, I would need to know how many \event and \period are in \eventsperiodslist which I don't know.
• With functions from the xstring package, I have problems with the curly brackets.

Any suggestions?

EDIT @egreg's comment From the values in the MWE below, I expect to be able to call \findminmax{\eventsperiodslist} with the expected output being something like \newcommand{\myminvalue}{-6} and \newcommand{\mymaxvalue}{23}.

EDIT: I do not mind defining my events and periods from an array and later build the commands \event and \period from this array.

MWE (at least of the \eventsperiodslist command)

\documentclass{article}
\begin{document}
\newcommand{\event}[3][non-dated]{*Some command*}

\newcommand{\period}[4][right]{*Some other command*}

\newcommand{\findminmax}[1]{
    *Some code to identify the minimum and maximum values*
    \newcommand{\myminvalue}{*calculated minimum value*}% Here: minimum is -6
    \newcommand{\mymaxvalue}{*calculated maximum value*}% Here: maximum is 23
}

\newcommand{\eventsperiodslist}{
    \event[dated]{-6}{Some text}
    \period{1}{5}{Nothing}
    \period[center]{2}{7}{Something else}
    \period[left]{4}{10}{Random text}
    \event[dated]{23}{Making a test}

\findminmax{\eventsperiodslist}

\end{document}
}

Answer 1

With the input as you show it you could simply redefine \event and \period and execute the contents of \eventsperiodslist inside a box. This way any possible output is only typeset into a box (so never shows up), and by the redefinition we can just compare the correct argument to the current minimum and maximum.

Limitations: If your list contains input that might have a global effect this will not be safe.

\documentclass{article}
\newcommand{\event}[3][non-dated]{Some command}
\newcommand{\period}[4][right]{Some other command}
\makeatletter
\newcount\AlMa@min
\newcount\AlMa@max
\newcommand\AlMa@period[4][]
  {%
    \AlMa@maxmin{#2}%
    \AlMa@maxmin{#3}%
  }
\newcommand\AlMa@event[3][]{\AlMa@maxmin{#2}}
\newcommand\AlMa@maxmin[1]
  {%
    \ifnum\numexpr#1\relax>\AlMa@max
      \global\AlMa@max=\numexpr#1\relax
    \fi
    \ifnum\numexpr#1\relax<\AlMa@min
      \global\AlMa@min=\numexpr#1\relax
    \fi
  }
\newcommand\findminmax[3]
  {%
    \begingroup
      \global\AlMa@max=-\number\maxdimen
      \global\AlMa@min=\number\maxdimen
      \let\period\AlMa@period
      \let\event\AlMa@event
      \sbox0{#1}%
      \edef\AlMa@tmp
        {%
          \endgroup
          \def\unexpanded{#2}{\the\AlMa@min}%
          \def\unexpanded{#3}{\the\AlMa@max}%
        }%
    \AlMa@tmp
  }
\makeatother
\newcommand{\eventsperiodslist}
  {%
    \event[dated]{-6}{Some text}%
    \period{1}{5}{Nothing}%
    \period[center]{2}{7}{Something else}%
    \period[left]{4}{10}{Random text}%
    \event[dated]{23}{Making a test}%
  }
% just allocating macro names
\newcommand\mymin{0}
\newcommand\mymax{0}
\findminmax{\eventsperiodslist}\mymin\mymax
\begin{document}
Minimum was \mymin, and maximum was \mymax.
\end{document}