Cfrgtkky

I am trying to build an environment with a switch, so that -- when turned on - only the text in the Brackets appear in the pdf file.

It would be great, if exceptions are possible and for marked* items the whole text could be printed.

Does something like this exist? I could not find an example.

documentclass{scrreprt}

usepackage{enumerate}

begin{document}

begin{description}

item[ABC] 12345

item[CDEF] 098765

item*[xxxx] yyyyy

end{description}

end{document}

You can use environ for manipulating the environment's contents more easily.

documentclass{article}

usepackage{xparse,environ}



ExplSyntaxOn

NewEnviron{xdesc}

 {

  begin{description}

  cp_xdesc_main:NV xdescitemshow BODY

  end{description}

 }



NewEnviron{xdesc*}

 {

  begin{description}

  cp_xdesc_main:NV xdescitemhide BODY

  end{description}

 }



cs_new_protected:Nn cp_xdesc_main:Nn

 {

  seq_set_split:Nnn l_cp_xdesc_items_in_seq { item } { #2 }

  seq_pop_left:NN l_cp_xdesc_items_in_seq l_tmpa_tl

  seq_clear:N l_cp_xdesc_items_out_seq

  seq_map_inline:Nn l_cp_xdesc_items_in_seq

   {

    seq_put_right:Nn l_cp_xdesc_items_out_seq { #1 ##1 endxdescitem }

   }

  seq_use:Nn l_cp_xdesc_items_out_seq { }

 }

cs_generate_variant:Nn cp_xdesc_main:Nn { NV }



NewDocumentCommand{xdescitemshow}{sO{}+u{endxdescitem}}

 {

  item[#2] #3

 }

NewDocumentCommand{xdescitemhide}{sO{}+u{endxdescitem}}

 {

  item[#2] IfBooleanT{#1}{#3}

 }

ExplSyntaxOff



begin{document}



section{Show}



begin{xdesc}

item[ABC] 12345



item[CDEF] 098765



item*[xxxx] yyyyy

end{xdesc}



section{Hide}



begin{xdesc*}

item[ABC] 12345

item[CDEF] 098765

item*[xxxx] yyyyy

end{xdesc*}



end{document}

The idea is to collect the contents and splitting it at item; the first item will be empty and we throw it away. Then we process each item by adding in front of it either xdescitemshow or xdescitemhide and ending them with the sentinel endxdescitem; the two commands process their arguments inserting item, collecting the optional argument (and possibly the *), then printing or discarding the following text up to endxdescitem.

Update March 2019

With new features of expl3 (seq_map_variable:NNn) and xparse (the implementation of features alike to environ), the code can be simplified.

documentclass{article}

usepackage{xparse}



ExplSyntaxOn

NewDocumentEnvironment{xdesc}{+b}

 {

  begin{description}

  cp_xdesc_main:Nn xdescitemshow { #1 }

  end{description}

 }{}



NewDocumentEnvironment{xdesc*}{+b}

 {

  begin{description}

  cp_xdesc_main:Nn xdescitemhide { #1 }

  end{description}

 }{}



seq_new:N l_cp_xdesc_items_seq

tl_new:N l__cp_xdesc_temp_tl



cs_new_protected:Nn cp_xdesc_main:Nn

 {

  % split the input at item

  seq_set_split:Nnn l_cp_xdesc_items_seq { item } { #2 }

  % throw away the first element, that's empty

  seq_pop_left:NN l_cp_xdesc_items_seq l_tmpa_tl

  %

  seq_map_variable:NNn l_cp_xdesc_items_seq l__cp_xdesc_temp_tl

   {

    exp_last_unbraced:NV #1 l__cp_xdesc_temp_tl stopxdescitem

   }

 }



NewDocumentCommand{xdescitemshow}{sO{}+u{stopxdescitem}}

 {

  item[#2] #3

 }

NewDocumentCommand{xdescitemhide}{sO{}+u{stopxdescitem}}

 {

  item[#2] IfBooleanT{#1}{#3}

 }

NewDocumentCommand{stopxdescitem}{}{} % for safety



ExplSyntaxOff



begin{document}



section{Show}



begin{xdesc}

item[ABC] 12345



item[CDEF] 098765



item*[xxxx] yyyyy

end{xdesc}



section{Hide}



begin{xdesc*}

item[ABC] 12345

item[CDEF] 098765

item*[xxxx] yyyyy

end{xdesc*}



end{document}

I don't know of a package that does this. If you are prepared to enclose the "item text" in braces so that for each item you type something like:

Item[ABC]{12345}

then this is relatively straightforward to do using the xparse package. All that you need to do is define an Item command that takes three arguments:

• an optional *
  


• an optional label for the item command, and,


• the "item text"

The Item command then processes the input using the tools described in the (see the xparse](https://www.ctan.org/pkg/xparse) manual and then does the appropriate things.

For example, you get the output

using the code:

documentclass{scrreprt}

usepackage{enumerate}

usepackage{xparse}

newififMySwitch% a "switch" for turning othe item text on/off



NewDocumentCommandItem{ som }{% *[label]{text}

IfBooleanTF{#1}{ IfNoValueTF{#2}{item #3}{item[#2]#3} }

  {IfNoValueTF{#2}{item}{item[#2]}ifMySwitch #3fi}

}



begin{document}



  Switched on: MySwitchtrue

  begin{description}

    Item[ABC]{12345}

    Item[CDEF]{098765}

    Item*[xxxx]{yyyyy}

  end{description}



  Switched off MySwitchfalse

  begin{description}

    Item[ABC]{12345}

    Item[CDEF]{098765}

    Item*[xxxx]{yyyyy}

  end{description}



end{document}

If you are not happy enclosing the "item text" in braces this is slightly trickier. The easiest way out that I see is to assume that the "item text" contains at most one paragraph, which seems reasonable to me, and then require that every item ends with a blank line. In particular, the very last item needs a blank line before the end{Description}.

If you assume this then you can essentially repeat the code above but now the item command delegates everything to a greedyItem command that reads in everything up to the end of the next paragraph as the item text. For LaTeX the "end of the next paragraph" means the next par, which is why par appears after the #3 in the definition of greedyItem. The following code achieves this:

documentclass{scrreprt}

usepackage{enumitem}



newlist{Description}{description}{3}% a new description environment

setlist[Description]{before=letitemItem}% in which the switch is automatic

letrealItem=item% save the "real" item for future use

usepackage{xparse}

newififMySwitch% switch on/switch off



defgreedyItem[#1][#2]#3par{% #3 = until end of paragraph

  IfBooleanTF{#1}{ IfNoValueTF{#2}{realItem #3}{realItem[#2]#3} }%

    {IfNoValueTF{#2}{realItem}{realItem[#2]}ifMySwitch #3fi}%

}

NewDocumentCommandItem{ so }{greedyItem[#1][#2]}



begin{document}



  Switched on: MySwitchtrue

  begin{Description}

    item[ABC]12345



    item[CDEF]098765



    item*[xxxx]yyyyy



  end{Description}



  Switched off MySwitchfalse

  begin{Description}

    item[ABC]12345



    item[CDEF]098765



    item*[xxxx]yyyyy



  end{Description}



end{document}

Btw, I have switched to using the enumitem package, which I prefer, and added a few bells and whistles to hide the code inside a new Description environment, which is the just the usual description environment with your switch automatically incorporated. The output is the same as before.