Cfrgtkky

I was getting unexpected results storing a parameter into a string variable, and added the statement "str_show:N l_tmpa_str" to produce debugging output. Texworks treats the output as an error. My first thought was to use str_log:N, but that does not exist.

My concerns are why I am getting an extraneous hyphen and quote around "semi-" and what the correct way is to get diagnostic output.

The reason for the extraneous characters in the underset is that the string functions and variablesare not intended for text that you need to render. Once I switched to token list variables for the text in the underset, everything worked.

documentclass{article}

usepackage{mathtools}

usepackage{xparse}



ExplSyntaxOn



% Render underscored with some variation of strict

NewDocumentCommand{strict}{O{strict} m}

  {

     show_strict:nn {#1} {#2}

  }



cs_new_protected:Npn show_strict:nn #1 #2

  {

    str_set:Nn l_tmpa_str {#1}

    l_tmpa_str~is~ l_tmpa_str

    str_show:N l_tmpa_str

    str_if_eq:eeTF {str_item:nn {#1} {-1}} {-}

      {

        str_set:Nx l_tmpa_str {{l_tmpa_str}strict}

      }

      {

        str_case:nn {#1}

        {

          {*}  {str_set:Nn l_tmpa_str {(semi-strict,strict)}}

          {**} {str_set:Nn l_tmpa_str {semi-strict~(strict)}}

        }

      }

    underset {textup{l_tmpa_str}} {#2}

  }



ExplSyntaxOff



begin{document}



begin{enumerate}

item Test $strict{{default}}$ \*

      expect underset with upright "strict"

item Test $strict[semi-]{{hyphen}}$

      expect underset with upright "semi-strict"

item Test $strict[*]{{star}}$

      expect underset with upright "(semi-strict,strict)"

item Test $strict[**]{{starstar}}$

      expect underset with upright "semi-strict (strict)"

end{enumerate}



end{document}

Yes, str_log:N and str_log:n were missing, but have been added for the next release, see https://github.com/latex3/latex3/blob/master/l3kernel/CHANGELOG.md and https://github.com/latex3/latex3/commit/83d2792ccf9e1c03b8a06e85c889d442da8e798c

In the meantime you can use tl_log:N, in your case it will log

> l_tmpa_str=strict.

> l_tmpa_str=semi-.

> l_tmpa_str=*.

> l_tmpa_str=**.