Mrthfx

I have a query with the maximum number of items that can be saved in an expl3 list. Thanks to the response that @egreg gave me in Avoid passing an empty [optional argument] an environment (with verbatim content) using xparse? I was able to finish the implementation of an environment capable of saving valid LaTeX code (including verbatim) in expl3lists ... something like a "fake ConTextbuffers".

Let me explain a bit, I have many question/answer files in which I have abused the use of filecontents to record temporary files and included them in environment based on environ (which did not support verbatim) and then use them in different parts of the documents.

With the new version of filecontentsdef it is not necessary to write the external files (included verbatim) to have them in a macro, thus the things and gathering ideas I have managed to create a listcontents environment which encapsulates filecontentsdefmacro, what run and save in a list, which I can access with usecontents[index]{list name}, the environment works perfectly.

My question is this, as the environment saves the content in one (or more lists), at some point the list will have a limit. What is the limit on the number of items I can save?

I have tested some files, but, I convert all my old files using a script to pass them to the new listcontents environment.

I leave here the example code (for sure it is not written in the perfect way, but it works)

documentclass{article}

usepackage{xparse}

usepackage{filecontentsdef}[2019/04/20] % last version 1.4 (ctan)

makeatletter

ExplSyntaxOn

% elementin{listname}

cs_new:Npn elementin #1

  {

  seq_count:c { l_listcontents_contents_#1_seq }

  }



% clearlist{listname}

cs_new:Npn clearlist #1

  {

  seq_clear_new:c { l_listcontents_contents_#1_seq }

  }



% @add@contents{listname}{{#1}}

NewDocumentCommand{@add@contents}{ m +m }

  {

  listcontents_add_contents:nn { #1 } { #2 }

  }



% usecontents[index]{listname}

DeclareExpandableDocumentCommand{usecontents}{ O{1} m }

  {

  listcontents_use_contents:nn { #1 } { #2 }

  }



cs_new_protected:Npn listcontents_add_contents:nn #1 #2

  {

  seq_if_exist:cF { l_listcontents_contents_#1_seq }

    { seq_new:c { l_listcontents_contents_#1_seq } }

  __listcontents_add_contents:nn { #1 } { #2 }

  }



cs_new_protected:Npn __listcontents_add_contents:nn #1 #2

  {

    tl_map_inline:nn { #2 }

    {

    seq_gput_right:cn { l_listcontents_contents_#1_seq } { ##1 }

    }

  }



cs_new:Npn listcontents_use_contents:nn #1 #2

  {

  seq_item:cn { l_listcontents_contents_#2_seq } { #1 }

  }



% tl vars and bool

tl_new:N l_add@tmpa@contents_tl

tl_new:N l_add@file@@contents_tl

bool_new:N l_write_file_bool

bool_new:N l_add_macro_bool

bool_set_true:N l_add_macro_bool



% [key=val] implementation

keys_define:nn { listcontents }

  {

    save-cmd    .tl_set:N         = l_listcontents_cmd_save_tl,

    save-cmd    .initial:n        = contents,

    save-env    .tl_set:N         = l_listcontents_env_save_tl,

    save-env    .initial:n        = contents,

    show-cmd    .bool_set:N       = l_listcontents_cmd_show_tl,

    show-cmd    .initial:n        = false,

    show-cmd    .value_required:n = true,

    show-env    .bool_set:N       = l_listcontents_env_show_tl,

    show-env    .initial:n        = false,

    show-env    .value_required:n = true,

    name-tmp    .tl_set:N         = l_tmp_name_output_tl,

    file-out    .code:n           = {

                                      bool_set_true:N l_write_file_bool

                                      keys_set:nn { listcontents }

                                       {

                                         name-tmp = { #1 }

                                       }

                                     } ,

    file-out    .value_required:n = true,

    file-use    .code:n           = {

                                      bool_set_false:N l_add_macro_bool

                                      bool_set_true:N l_write_file_bool

                                      keys_set:nn { listcontents }

                                       {

                                         name-tmp = { #1 } ,

                                       }

                                     } ,

    file-out    .value_required:n = true,

    show-all    .meta:n           = { show-env = true , show-cmd = true },

  }



keys_define:nn { listcontents / scontents }

  {

    show-cmd .code:n = { keys_set:nn { listcontents } { show-cmd = { #1 } } } ,

    save-cmd .code:n = { keys_set:nn { listcontents } { save-cmd = { #1 } } } ,

  }



NewDocumentCommand{Setlistcontents}{ +m }

  {

    keys_set:nn { listcontents } { #1 }

  }



% scontents[...]{...} NO verbatim and par support

NewDocumentCommand{scontents}{ O{} m }

  {

   group_begin:

   IfNoValueF { #1 } { keys_set:nn { listcontents / scontents } { #1 } }

   @add@contents{ l_listcontents_cmd_save_tl }{ { #2 } } % pass direct to list

   IfBooleanT { l_listcontents_cmd_show_tl } { usecontents[-1]{ l_listcontents_cmd_save_tl} }

   group_end:

  }



% begin{listcontents}[key val in one line] verbatim env suport in macro

NewDocumentEnvironment{ listcontents }{}

  {

   char_set_catcode_active:N ^^M

   listcontents_start_listcontents:w

  }

  {

   IfBooleanTF{ l_write_file_bool } { endfilecontentsdef } { endfilecontentsdefmacro }

   group_end:

    IfBooleanTF{ l_add_macro_bool }

    {

     tl_put_right:Nx l_tmpb_tl {

     tex_newlinechar:D = 13 tex_everyeof:D = {noexpand}

     exp_not:N scantokens exp_after:wN { l_tmpa_tl }

     tex_newlinechar:D = 10relax

      }

     tl_put_right:Nx l_add@tmpa@contents_tl {

     exp_not:N @add@contents { exp_not:V l_listcontents_env_save_tl } { {exp_not:V l_tmpb_tl } }

      }

     l_add@tmpa@contents_tl

    }

    {

     tl_put_right:Nx l_add@file@@contents_tl {

     exp_not:N @add@contents { exp_not:V l_listcontents_env_save_tl } { { exp_not:N input { exp_not:V l_tmp_name_output_tl } } }

       }

     l_add@file@@contents_tl

    }

     IfBooleanT{ l_listcontents_env_show_tl } { usecontents[-1]{ l_listcontents_env_save_tl} }

  }



cs_new_protected:Npn listcontents_listcontents_set:w [#1]

  {

   keys_set:nn { listcontents } { #1 }

  }



group_begin:

char_set_catcode_active:N ^^M

cs_new_protected:Npn listcontents_start_listcontents:w #1 ^^M

  {

  tl_if_blank:nF { #1 } { listcontents_listcontents_set:w #1 }

  group_begin:

      IfBooleanTF{ l_write_file_bool }

        { use:c { filecontentsdef* } { l_tmp_name_output_tl } { l_tmpa_tl } ^^M }

        { use:c { filecontentsdefmacro } { l_tmpa_tl } ^^M }

  }

group_end:

ExplSyntaxOff

makeatother

% only for example

usepackage[margin=0.5in,noheadfoot,papersize={8.5in,11in}]{geometry} 

usepackage{pgffor} 

setlength{parindent}{0pt}

pagestyle{empty}

begin{document}

section{Test begin{listcontents}[key=val]}

Test verb+begin{listcontents}+ no verb+[key=val]+par



begin{listcontents}

Using verb+listcontents+ env no verb+[key=val]+, save in list verb+contents+ with index 1.par

We have coded this in LaTeX: $E=mc^2$.par

begin{verbatim}

      (A) verbatim environment

end{verbatim}

end{listcontents}



Test verb+begin{listcontents}[file-out=jobname.tsc]+par



begin{listcontents}[file-out=jobname.tsc]

Using verb+listcontents+ env with verb+[file-out=jobname.tsc]+, save in list verb+contents+ with index 2.

We have coded this in LaTeX: $E=mc^2$.par

begin{verbatim*}

      (B) verbatim environment

end{verbatim*}

end{listcontents}



Test verb+begin{listcontents}[file-use=jobname.tsc]+par



begin{listcontents}[file-use=jobname-1.tsc]

Using verb+listcontents+ env with verb+[file-use=jobname-1.tsc]+, pass verb+input{jobname-1.tsc}+

to list verb+contents+ with index 3. We have coded this in LaTeX: $E=mc^2$.par

begin{verbatim}

      (C) verbatim environment

end{verbatim}

end{listcontents}



Test verb+begin{listcontents}[show-env=true]+par



begin{listcontents}[show-env=true]

Using verb+listcontents+ env with verb+[show-env=true]+, save in list verb+contents+ with index 4.

We have coded this in LaTeX: $E=mc^2$.par

begin{verbatim*}

      (D) verbatim environment

end{verbatim*}

end{listcontents}



Test verb+scontents{...}+par

scontents{Using texttt{scontents} command (no verbatim and par suport), save in list texttt{contents} with index 5}



section{Execution in reverse}

The total verb+contents saved+ (environment and command) saved in verb+contents+ list are elementin{contents}.par



usecontents[5]{contents}par

usecontents{contents}



section{Using a loop (pgffor)}



foreach i in {1,...,elementin{contents}} {usecontents[i]{contents}}



section{A simple aplication}



newcounter{exeNr}

newenvironment{exercise}

  {refstepcounter{exeNr}parnoindent This is exercise~theexeNr}

  {par}

subsection{Exercises}

begin{exercise}

end{exercise}

begin{listcontents}[save-env=myansewer]

This is the answer to exercise 1, the shebang line for a Perl script



begin{verbatim}

#!/usr/bin/env perl

end{verbatim}

end{listcontents}



begin{exercise}

end{exercise}

begin{listcontents}[save-env=myansewer]

This is the answer to exercise 2

end{listcontents}



begin{exercise}

end{exercise}

scontents[save-cmd=myansewer]{This is the answer to exercise 3}



subsection{Answers}

newcounter{ansNr}

newenvironment{answer}

  {refstepcounter{ansNr}parnoindent Answer~theansNr:}

  {par}



foreach i in {1,...,elementin{myansewer}} {

begin{answer}

usecontents[i]{myansewer}

end{answer}

}

end{document}

An image of what the output is like:

Comments are welcome

regards