Htydjtk

I want to make a shortcut for

href{tel:0123456789}{01,23,45,67,89}

I can use StrSubstitute from the xstring package as

StrSubstitute{01 23 45 67 89}{ }{,}

inside the second argument to href. But the same thing with

StrSubstitute{01 23 45 67 89}{ }{}

in the first argument won't work.

I think, I understand that this is an issue with macro expansion order. But how can I get LaTeX to first expand StrSubstitute into a string that can be parsed by href?

Here is a minimal example of what I actually want to achieve:

documentclass{minimal}



usepackage{xstring}

usepackage{hyperref}



newcommandphone[1]{href{tel:StrSubstitute{#1}{ }{}}{StrSubstitute{#1}{ }{,}}}



begin{document}



    href{tel:0123456789}{01,23,45,67,89}



    href{StrSubstitute{01 23 45 67 89}{ }{}}{StrSubstitute{01 23 45 67 89}{ }{,}}



    phone{01 23 45 67 89}



end{document}

You can't use StrSubstitute in those places, because it doesn't produce the string after the substitution, but rather a fairly complicated set of instructions to produce that string.

A more complicated solution that avoids the need to input spaces between pairs of digits, so it will work even if you forget them.

documentclass{article}



usepackage{xparse}

usepackage{hyperref}



ExplSyntaxOn



NewDocumentCommand{phone}{m}

 {

  dlichti_phone:n { #1 }

 }



tl_new:N l_dlichti_phone_href_tl

tl_new:N l_dlichti_phone_print_tl



cs_new_protected:Nn dlichti_phone:n

 {

  tl_set:Nx l_dlichti_phone_href_tl { #1 }

  % remove all spaces

  tl_replace_all:Nnn l_dlichti_phone_href_tl { ~ } { }

  % save a copy

  tl_set_eq:NN l_dlichti_phone_print_tl l_dlichti_phone_href_tl

  % insert a thin space between any pair of digits

  regex_replace_all:nnN

   { ([0-9][0-9]) } % two digits followed by another digit

   { 1c{,} } % the same with , in between

   l_dlichti_phone_print_tl

  % remove the trailing ,

  regex_replace_once:nnN { c{,} Z } { } l_dlichti_phone_print_tl

  dlichti_phone_href:VVV

   c_colon_str

   l_dlichti_phone_href_tl

   l_dlichti_phone_print_tl

 }

cs_new_protected:Nn dlichti_phone_href:nnn

 {

  href{tel#1#2}{#3}

 }

cs_generate_variant:Nn dlichti_phone_href:nnn { VVV }



ExplSyntaxOff



begin{document}



phone{01 23 45 67 89}



phone{0123456789}



end{document}

Expand the string substitution first by storing it in an argument, which you can then use with hyperref's href:

documentclass{article}



usepackage{xstring}

usepackage{hyperref}



newcommandphone[1]{%

  StrSubstitute{#1}{ }{}[firstarg]% Store first substitution in firstarg

  StrSubstitute{#1}{ }{,}[secondarg]% Store second substitution in secondarg

  href{tel:firstarg}{secondarg}% Use stored arguments in href

}



begin{document}



href{tel:0123456789}{01,23,45,67,89}



phone{01 23 45 67 89}



end{document}

The xstring commands are not expandable so can't in general be used inline in other commands. You can use a simple expandable replacement here.

documentclass{minimal}





usepackage{hyperref}



makeatletter

defzza#1 {#1zza}

defzzb#1 {#1,zzb}

newcommandphone[1]{{def!##1{}def$##1##2{}href{tel:zza#1! }{zzb#1$ }}}

makeatother



begin{document}



    href{tel:0123456789}{01,23,45,67,89}



    phone{01 23 45 67 89}



end{document}