Dear all,



As those who have followed the list for some time know, there were 

discussions of introducing verbatim arguments in xparse. This was rejected

for a very good reason: if the verbatim-like commands are not having the 

first look at the argument, then comment characters and spaces have been 

lost irretrievably. Thus, the user has to be made aware that nesting is a 

problem for verbatim. The proposal I describe below forces the user to 

explicitly indicate that the command that he is using will contain verbatim 

text.





Namely, in the package `cprotect.dtx`, I introduced the command 

`\cprotect` that acts somehow like a prefix: the argument of the 

following macro is read verbatim, and `\scantoken`ed when it 

is used. A typical example of use is



\cprotect \section { Title \cprotect \footnote { Foot \verb|^^|. } }



This will put the expected verbatim in a footnote attached to the section 

called "Title". This works in moving arguments (e.g. Table of Contents). 

So far, the implementation (is dirty and) only works for one argument. I 

plan to extend it to any command declared using xparse.





It might be possible to do error checking: each `\cprotect` should check 

somehow that it is "at the top" (i.e., it is the first one to look at its 

argument), or that it is within a `\cprotect`ed command. 

   Any idea how to do that?

If the error checking fails, throw an error, and try to recover by using the

harmless character sequences mentionned a few times in the past on this

list.





For the syntax, the naive thing is to simply get `\cprotect` to  grab all 

the arguments verbatim, and reread them when needed, but for 

performance reasons, it could be better to say explicitly for each 

argument whether it needs `\cprotect`ion. Any suggestions for the 

syntax in this case? 





Best regards,

Bruno Le Floch,

new to the list.





PS: Also, a small crazy idea (I see no practical application for that):

In LaTeX3, we can generate variants of macros with different types 

of arguments (using \cs_generate_variant:Nn). Could/should the 

same thing be done at the layer above? In other words, should it be 

possible to take a DocumentCommand, and change the delimiters, or 

change an argument from being optional to being mandatory, or from 

being mandatory to being  optional with default, ...?