Customize acronyms to set description as italic

Question

I am using glossaries package and the \newacronym command for a document, I want the description to be printed as italic text the first time it appears, but I dont want to do this in every definition of the acronym, is there a way to modify an internal hook or set some style that makes the long description automatically set to italic

Answer 1

With just the base glossaries package, you can use something like this example from the glossaries gallery:

% arara: pdflatex
% arara: makeglossaries
% arara: pdflatex
\documentclass{article}

\usepackage[colorlinks]{hyperref}
\usepackage[toc,acronymlists={main}]{glossaries}
\usepackage{glossary-mcols}

\makeglossaries

\newacronymstyle{long-short-emph}%
{%
  \ifglshaslong{\glslabel}%
  {% acronym
   % This is an adaptation of \glsgenacfmt
    \ifdefempty\glscustomtext
    {%
      \ifglsused\glslabel
      {%
        \glsifplural
        {%
          \glscapscase
          {%
            \acronymfont{\glsentryshortpl{\glslabel}}\glsinsert
          }%
          {%
            \acronymfont{\Glsentryshortpl{\glslabel}}\glsinsert
          }%
          {%
            \mfirstucMakeUppercase
              {\acronymfont{\glsentryshortpl{\glslabel}}\glsinsert}%
          }%
        }%
        {%
          \glscapscase
          {%
            \acronymfont{\glsentryshort{\glslabel}}\glsinsert
          }%
          {%
            \acronymfont{\Glsentryshort{\glslabel}}\glsinsert
          }%
          {%
            \mfirstucMakeUppercase
              {\acronymfont{\glsentryshort{\glslabel}}\glsinsert}%
          }%
        }%
      }%
      {%
        \glsifplural
        {%
          \glscapscase
          {%
            \emph{\glsentrylongpl{\glslabel}\glsinsert}\space
            (\firstacronymfont{\glsentryshortpl{\glslabel}})%
          }%
          {%
            \emph{\Glsentrylongpl{\glslabel}{\glsinsert}}\space
            (\firstacronymfont{\glsentryshortpl{\glslabel}})%
          }%
          {%
            \mfirstucMakeUppercase
              {\emph{\glsentrylongpl{\glslabel}{\glsinsert}}\space
               (\firstacronymfont{\glsentryshortpl{\glslabel}})}%
          }%
        }%
        {%
          \glscapscase
          {%
            \emph{\glsentrylong{\glslabel}\glsinsert}\space
            (\firstacronymfont{\glsentryshort{\glslabel}})%
          }%
          {%
            \emph{\Glsentrylong{\glslabel}\glsinsert}\space
            (\firstacronymfont{\glsentryshort{\glslabel}})%
          }%
          {%
            \mfirstucMakeUppercase
             {\emph{\glsentrylong{\glslabel}\glsinsert}\space
             (\firstacronymfont{\glsentryshort{\glslabel}})}%
          }%
        }%
      }%
    }%
    {%
      \glscustomtext
    }%
  }%
  {% regular term
    \ifglsused{\glslabel}{\glsgenentryfmt}{\emph{\glsgenentryfmt}}%
  }%
}%
{%
  \GlsUseAcrStyleDefs{long-short}%
}

\setacronymstyle{long-short-emph}

\loadglsentries{example-glossaries-brief}

\loadglsentries{example-glossaries-acronym}

\begin{document}

\section{First Use}

Regular entries: \gls{ac}, \gls{accumsan}, \gls{amet},
\gls{bibendum}, \gls{consectetuer}, \gls{diam}.

Acronyms: \gls{aeu}, \gls{afm}, \gls{anp}, \gls{cas},
\gls{cdg}, \gls{cea}, \gls{dia}.

\section{Next Use}

Regular entries: \gls{ac}, \gls{accumsan}, \gls{amet},
\gls{bibendum}, \gls{consectetuer}, \gls{diam}.

Acronyms: \gls{aeu}, \gls{afm}, \gls{anp}, \gls{cas},
\gls{cdg}, \gls{cea}, \gls{dia}.

Full form: \acrfull{aeu}.

\printglossary[style=mcolindex]

\end{document}

This produces:

Alternatively, you can use the extension package glossaries-extra. This uses a different mechanism for abbreviations, which are defined using \newabbreviation (same syntax as \newacronym). The abbreviation styles are set using \setabbreviationstyle[category]{style-name}. To allow for easy conversion, \newacronym is redefined in terms of \newabbreviation with category=acronym, which means the style needs to be set with \setabbreviationstyle[acronym]{style-name}. The long-short abbreviation style uses \glsfirstlongdefaultfont for the long-form font on first use. This makes for a much simpler document:

\documentclass{article}

\usepackage[colorlinks]{hyperref}
\usepackage{glossaries-extra}
\usepackage{glossary-mcols}

\makeglossaries

\renewcommand{\glsfirstlongdefaultfont}[1]{\emph{#1}}

\setabbreviationstyle[acronym]{long-short}

\loadglsentries{example-glossaries-brief}

\loadglsentries{example-glossaries-acronym}

\begin{document}

\section{First Use}

Regular entries: \gls{ac}, \gls{accumsan}, \gls{amet},
\gls{bibendum}, \gls{consectetuer}, \gls{diam}.

Acronyms: \gls{aeu}, \gls{afm}, \gls{anp}, \gls{cas},
\gls{cdg}, \gls{cea}, \gls{dia}.

\section{Next Use}

Regular entries: \gls{ac}, \gls{accumsan}, \gls{amet},
\gls{bibendum}, \gls{consectetuer}, \gls{diam}.

Acronyms: \gls{aeu}, \gls{afm}, \gls{anp}, \gls{cas},
\gls{cdg}, \gls{cea}, \gls{dia}.

Full form: \glsxtrfull{aeu}.

\printglossary[style=mcolindex]

\end{document}

This produces a similar result, except for the explicit full form at the end, which in this case also has the long form in italics.

Note that with \setabbreviationstyle you need to use \glsxtrfull not \acrfull. Similarly \glsxtrshort instead of \acrshort and \glsxtrlong instead of \acrlong. The \acr... commands are designed for use with the base glossaries acronym mechanism and don't allow for the glossaries-extra style settings.

Answer 2

from The users guide (page 110)

\glstextformat{< text >}

For example, to make all link text appear in a sans-serif font, do:

\renewcommand*{\glstextformat}[1]{\textsf{#1}}

In your case you could use \glstextformat to define all linked text to be italics. Here's a MWE

\documentclass{article}

\usepackage{glossaries} 

\newacronym{svm}{SVM}{support vector machine}
\makeglossaries
\renewcommand{\glstextformat}[1]{\textit{#1}}

\begin{document}
    blah balh blah \gls{svm} some more text and then \gls{svm}

    \printglossaries
\end{document}