Kdtyjb

I'd like to construct a macro that can be used to define commands. Those commands behave like variables or structs of variables, such that they can contain multiple values. The "member" is passed via an optional argument. I use it to define template environments and to have different strings for different languages, which need to be present in the document simultaneously.

Here's what I had and works.

newcommandMakeLocaleVar[1]{%

    global@namedef{#1:en}{{scriptsize (Use {tttextbackslash #1[en]} to replace this text.)}}%

    global@namedef{#1:fi}{{scriptsize (Use {tttextbackslash #1[fi]} to replace this text.)}}%

    expandafternewcommandcsname #1endcsname[2][]{%

        ifthenelse{equal{##1}{}}{%

            global@namedef{#1:en}{##2}%

            global@namedef{#1:fi}{##2}%

        }{%

            global@namedef{#1:##1}{##2}%

        }%

    }%

    expandafternewcommandcsname Emit#1endcsname[1][en]{@nameuse{#1:##1}}%

}

First the default values are set. Then a command is created that sets the values according to the optional argument. If none, set value for all locales.

% In cls: define command

MakeLocaleVar{Faculty}



% In main tex: set values

Faculty{This faculty} % for all values

Faculty[fi]{Tämä tiedekunta} % for a specific one



% In cls environments: use values

EmitFaculty[en]

EmitFaculty[fi]



% Now in addition I'd like to be able to:

MakeLocaleVar[en,fi,de]{Faculty}

I tried to modify the command to accept arbitrary locales, but something's not working.

newcommandMakeLocaleVar[2][en,fi]{%

    foreach n in {#1}{%

        global@namedef{#2:n}{%

            {scriptsize (Use {tttextbackslash #2[n]} to replace this text.)}%

        }%

    }%

    expandafternewcommandcsname #2endcsname[2][]{%

        ifthenelse{equal{##1}{}}{%

            foreach n in {#1}{%

                global@namedef{#2:n}{##2}%

            }%

        }{%

            global@namedef{#2:##1}{##2}%

        }%

    }%

    expandafternewcommandcsname Emit#2endcsname[1][en]{@nameuse{#2:##1}}%

}

If I set values that are used, everything is fine and dandy. It is when values are not set that my custom environments break and the default message shown is just Use Cmd[] to..., so without the locale names.

Any idea as to what is going on?

As mentioned in the comment, your main issue was that the n in the replacement text of the @namedef was not expanded to its value. The replacement text for Faculty:fi for example thus remained literally

{scriptsize (Use {tttextbackslash #2[n]} to replace this text.)}%

with n. In most contexts where the macro would be called n would be undefined and you would get an error. You want the macro replacement text to be constructed so that n becomes its expansion, i.e. fi. The easiest way to get that done properly is probably a helper macro. This answer will show two approaches: One with etoolbox and its list macros and one with your code that uses expandafter and a helper macro. etoolbox's loop work by passing the value of the loop variable directly as an argument to a helper macro.

In the first argument of @namedef (i.e. the #2:n), the n would be expanded automatically so that it would really become fi there.

Here is a solution using etoolbox and its list macros. Some explanations are inline. The advantage of this approach is that there is no need for expansion of the loop variable (n) as the loop is directly implemented as a macro.

documentclass[english,finnish]{article}

usepackage[T1]{fontenc}

usepackage[utf8]{inputenc}

usepackage{babel}



usepackage{etoolbox}



makeatletter

% {<name>}{<lang>}

newcommand*{mlv@defaultvalue}[2]{%

  csdef{#1@#2}{%

    {scriptsize (Use {ttfamilytextbackslash #1[#2]} to replace this text.)}}}

% {<repl. text>}{<name>}{<lang>}

% the unusual order instead of the more natural {<name>}{<lang>}{<repl. text>}

% makes for a more elegant call to forcsvlist

newcommand*{mlv@realvalue}[3]{%

  csdef{#2@#3}{#1}}



% [<langs>]{<name>}

% forcsvlist{<macro>}{<item_1, item_2, ..., item_n>}

% calls <macro> once with each item_i as argument

% <macro>{<item_1>}, <macro>{<item_2>}

% since the items are the <lang> argument it must be the last

% argument to mlv@defaultvalue and mlv@realvalue

newcommandMakeLocaleVar[2][en,fi]{%

  forcsvlist{mlv@defaultvalue{#2}}{#1}%

  expandafternewcommandcsname #2endcsname[2][]{%

    ifblank{##1}

      {forcsvlist{mlv@realvalue{##2}{#2}}{#1}}%

      {mlv@realvalue{##2}{#2}{##1}}}%

  expandafternewcommandcsname Emit#2endcsname[1][en]{csuse{#2@##1}}%

}

makeatother



begin{document}



MakeLocaleVar{Faculty}



% In main tex: set values

Faculty{This faculty} % for all values

Faculty[fi]{Tämä tiedekunta} % for a specific one



% In cls environments: use values

EmitFaculty[en]

EmitFaculty[fi]



% Now in addition I'd like to be able to:

MakeLocaleVar[en,fi,de]{Gaculty}



EmitGaculty[en]

EmitGaculty[fi]

EmitGaculty[de]



Gaculty{Foo}

EmitGaculty[en]

EmitGaculty[fi]

EmitGaculty[de]



Gaculty[fi]{Föö}

EmitGaculty[en]

EmitGaculty[fi]

EmitGaculty[de]

end{document}

If you want to stick to your version with foreach and ifthenelse, you can make use of a helper function.

The trick is that we need to expand n so that we get its actual value. This is possible with expandafter, but to avoid having to use it with surgical precision to jump over many tokens, a helper function is useful.

documentclass[english,finnish]{article}

usepackage[T1]{fontenc}

usepackage[utf8]{inputenc}

usepackage{babel}



usepackage{ifthen}

usepackage{tikz}



makeatletter

% helper for easier control of expansion

% {<lang>}{<name>}

newcommand*{mlv@helper}[2]{%

  global@namedef{#2:#1}{%

    {scriptsize (Use {ttfamilytextbackslash #2[#1]} to replace this text.)}%

  }%

}



% n must be expanded to be useful.

% The first argument of @namedef automatically expands it,

% but the second does not.

% Here we use a helper function to expand n

% before it is processed.

newcommandMakeLocaleVar[2][en,fi]{%

    foreach n in {#1}{%

        expandaftermlv@helperexpandafter{n}{#2}%

    }%

    expandafternewcommandcsname #2endcsname[2][]{%

        ifthenelse{equal{##1}{}}{%

            foreach n in {#1}{%

                global@namedef{#2:n}{##2}%

            }%

        }{%

            global@namedef{#2:##1}{##2}%

        }%

    }%

    expandafternewcommandcsname Emit#2endcsname[1][en]{@nameuse{#2:##1}}%

}

makeatother



begin{document}



MakeLocaleVar{Faculty}



% In main tex: set values

Faculty{This faculty} % for all values

Faculty[fi]{Tämä tiedekunta} % for a specific one



% In cls environments: use values

EmitFaculty[en]

EmitFaculty[fi]



% Now in addition I'd like to be able to:

MakeLocaleVar[en,fi,de]{Gaculty}



EmitGaculty[en]

EmitGaculty[fi]

EmitGaculty[de]



Gaculty{Foo}

EmitGaculty[en]

EmitGaculty[fi]

EmitGaculty[de]



Gaculty[fi]{Föö}

EmitGaculty[en]

EmitGaculty[fi]

EmitGaculty[de]

end{document}