How to turn a LaTeX3 package key fontsize value into a command?

Question

I do not know how to search for this issue as backwards slash or \ in questions has not gleaned anything useful. How can I set a key-value and then use a font size value without having to use a command in the package options please, e.g.

\usepackage[superscript-fontsize=large]{aminosymb}

instead of

\usepackage[superscript-fontsize=\large]{aminosymb}

I would prefer for the package I am writing to not have to put the backwards slash in the package options although this is always a backup. For instance, my MWE produces this:

using this command:

\NewDocumentCommand { \aasp } { m m }
  {
    \residueString:nn { #1 } { \l_aminosymb_residue_style_tl }
    \textsuperscript{$\l_superscript_font_size_tl\mkern-1mu#2\mkern-1.5mu$}
  }

I do not know if there is a LaTeX3 command to convert tokens into a command, does anyone know how this can be done please? MWE:

\begin{filecontents}[overwrite]{aminosymb.sty}
\RequirePackage{l3keys2e}
\ProvidesExplPackage
  {aminosymb}
  {today}
  {version}
  {Typesetting amino acid residues with notation and numbers}
\ExplSyntaxOn
\tl_new:N \l_aminosymb_residue_style_tl
\tl_new:N \l_superscript_font_size_tl
\keys_define:nn { AminoSymb / Package }
  {
    style .tl_set:N  = \l_aminosymb_residue_style_tl,
    style .initial:n = abbrev-firstcap,
    superscript-fontsize .tl_set:N = \l_superscript_font_size_tl,
    superscript-fontsize .initial:n = scriptstyle,
  }
\ProcessKeysOptions { AminoSymb / Package }
\prop_new:N \l_abbrev_ala_prop
\prop_new:N \l_abbrev_all_prop
\prop_set_from_keyval:Nn \l_abbrev_ala_prop
  {
    initial-lower=a,
    abbrev-firstcap = Ala,
  }
\prop_set_from_keyval:Nn \l_abbrev_all_prop
  {
    ala = \l_abbrev_ala_prop,
  }
\cs_new:Npn \residueString:nn #1#2
  {
    \tl_set:Nx\l_residue{#1}
    \tl_set:Nx\l_style{#2}
    \prop_map_function:NN \l_abbrev_all_prop __abbrev_aux:nn
  }
\cs_generate_variant:Nn\prop_item:Nn{Ne}
\cs_new:Npn __abbrev_aux:nn #1#2
     {
        \prop_map_inline:Nn #2
        {
          \tl_if_eq:NnT
          \l_residue
          {##2}
          {\prop_item:Ne#2{\l_style}}
        }
      }
\NewDocumentCommand { \aasp } { m m }
  {
    \residueString:nn { #1 } { \l_aminosymb_residue_style_tl }
    \textsuperscript{$\l_superscript_font_size_tl\mkern-1mu#2\mkern-1.5mu$}
  }
\ExplSyntaxOff
\end{filecontents}
\documentclass{article}
\usepackage[superscript-fontsize=large]{aminosymb}
\begin{document}
\aasp{a}{323}
\end{document}

Apologies if this is a duplicate, I do not know how to search for this issue due to the nature of the \ command.

Consider not using package options at all, but instead a setup-macro that can be used after the package is loaded. — Skillmon, Oct 11 '23 at 05:41
Please note that you're violating the naming conventions of expl3. See my edited answer for a version that fixes it. All your functions should contain the module name, same is true for all your variables. — Skillmon, Oct 11 '23 at 05:54
@Skillmon I appreciate the feedback, LaTeX3 is some learning curve but will be worth it, thanks for the help! Will fix it in my main document now — JamesT, Oct 11 '23 at 05:56
In summary, a variable should be called \<scope>_<module>_<description>_<type> or if it's private \<scope>__<module>_<description>_<type>. And a function should always be called \<module>_<description>:<args> or if it's private \__<module>_<description>:<args>. — Skillmon, Oct 11 '23 at 05:56

Skillmon · Accepted Answer · 2023-10-11T15:27:09.383

You can use \cs_if_exist_use:c, if you want to throw an error if it's not available you can as well use \cs_if_exist_use:cF.

The following silently ignores an unknown command. Also I fixed the way you set the font command (has to be used outside of the maths context). And I also put \exp_stop_f: after your \mkern so that they don't affect #2.

Additionally I removed the hard dependency on l3keys2e, as you can use the built-in \ProcessKeyOptions in recent kernels, and only need l3keys2e for older LaTeX versions.

\begin{filecontents}[overwrite]{aminosymb.sty}
\ProvidesExplPackage
  {aminosymb}
  {today}
  {version}
  {Typesetting amino acid residues with notation and numbers}
\ExplSyntaxOn
\tl_new:N \l_aminosymb_residue_style_tl
\tl_new:N \l_aminosymb_superscript_font_size_tl
\keys_define:nn { AminoSymb / Package }
  {
    style .tl_set:N  = \l_aminosymb_residue_style_tl,
    style .initial:n = abbrev-firstcap,
    superscript-fontsize .tl_set:N = \l_aminosymb_superscript_font_size_tl,
    superscript-fontsize .initial:n = scriptstyle,
  }
\cs_if_exist:NTF \ProcessKeyOptions
  {
    \ProcessKeyOptions [ AminoSymb / Package ]
  }
  {
    \RequirePackage{l3keys2e}
    \ProcessKeysOptions { AminoSymb / Package }
  }
\prop_new:N \l_aminosymb_abbrev_ala_prop
\prop_new:N \l_aminosymb_abbrev_all_prop
\prop_set_from_keyval:Nn \l_aminosymb_abbrev_ala_prop
  {
    initial-lower=a,
    abbrev-firstcap = Ala,
  }
\prop_set_from_keyval:Nn \l_aminosymb_abbrev_all_prop
  {
    ala = \l_aminosymb_abbrev_ala_prop,
  }
\cs_new:Npn \aminosymb_residueString:nn #1#2
  {
    \tl_set:Nx\l_aminosymb_residue_tl{#1}
    \tl_set:Nx\l_aminosymb_style_tl{#2}
    \prop_map_function:NN \l_aminosymb_abbrev_all_prop __aminosymb_abbrev_aux:nn
  }
\cs_generate_variant:Nn\prop_item:Nn{Ne}
\cs_new:Npn __aminosymb_abbrev_aux:nn #1#2
     {
        \prop_map_inline:Nn #2
        {
          \tl_if_eq:NnT
          \l_aminosymb_residue_tl
          {##2}
          {\prop_item:Ne#2{\l_aminosymb_style_tl}}
        }
      }
\NewDocumentCommand { \aasp } { m m }
  {
    \aminosymb_residueString:nn { #1 } { \l_aminosymb_residue_style_tl }
    \textsuperscript
      {
        \cs_if_exist_use:c { \l_aminosymb_superscript_font_size_tl }
        $ \mkern-1mu\exp_stop_f: #2 \mkern-1.5mu\exp_stop_f: $
      }
  }
\ExplSyntaxOff
\end{filecontents}
\documentclass{article}
\usepackage[superscript-fontsize=large]{aminosymb}
\begin{document}
\aasp{a}{323}
\end{document}

How to turn a LaTeX3 package key fontsize value into a command?

1 Answers1

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