How to use a user-defined command in glossary file?

Question

I've a user-defined symbol like this:

\newcommand{\myexclam}{\mathrel{\stackinset{c}{}{t}{}{\rotatebox{-45}{\scalebox{.5}{$/$}}}{$!$}}}

This symbol should be used in one of my glossary's entries as below (gloss.tex):

\newglossaryentry{mykey}{name={\ensuremath{\delta_{\text{act}}(a,\tau)\myexclam}}, description={Activity automaton}}

and here is main.tex:

\documentclass[doublespaced,12pt]{article}

\usepackage{amsmath}
\usepackage{graphicx}
\usepackage[english]{babel}
\usepackage[symbols]{glossaries}
\usepackage{stackengine}
\usepackage{hyperref}

\newcommand{\myexclam}{\mathrel{\stackinset{c}{}{t}{}{\rotatebox{-45}{\scalebox{.5}{$/$}}}{$!$}}}

\makenoidxglossaries
\loadglsentries{gloss}

\begin{document}

    Here is my formula \gls{mykey}

    \printnoidxglossary[sort=standard,title={List of Symbols}]      

\end{document}

But the compilation throws an undefined control sequence corresponding to \myexclam.

How can I properly use this command in my glossary?

Answer 1

In this case, \myexclam must be \protected in the \newglossaryentry.

EDITED to add a sort= key to \newglossaryentry, since the name is non-alphabetic, per Nicola's instruction. Also, loaded hyperref prior to glossaries.

\documentclass[doublespaced,12pt]{article}
\usepackage{filecontents}
\begin{filecontents*}{gloss.tex}
\newglossaryentry{mykey}{name={\ensuremath{\delta_{\text{act}}(a,\tau)\protect\myexclam}}, 
  description={Activity automaton},sort={delta activity}}
\end{filecontents*}

\usepackage{amsmath}
\usepackage{graphicx}
\usepackage[english]{babel}
\usepackage{hyperref}
\usepackage[symbols]{glossaries}
\usepackage{stackengine}

\newcommand{\myexclam}{\mathrel{\stackinset{c}{}{t}{}{\rotatebox{-45}{%
  \scalebox{.5}{$/$}}}{$!$}}}

\makenoidxglossaries
\loadglsentries{gloss}

\begin{document}

    Here is my formula \gls{mykey}

    \printnoidxglossary[sort=standard,title={List of Symbols}]      

\end{document}

In the event that there were multiple macros needing protection (for example, if \myexclam were used more than once), it might just be easier to define it this way, so that only a single \protect is required:

\begin{filecontents*}{gloss.tex}
\newcommand\newname{\ensuremath{\myexclam\delta_{\text{act}}(a,\tau)\myexclam}}
\newglossaryentry{mykey}{name={\protect\newname}, description={Activity automaton},
  sort={delta activity}}
\end{filecontents*}