Mrthfx

Do I advise this: No!!!

The catcode of macro escape character is 0, i.e. the catcode of / has to be changed to 0.

I did not test for the literal / however.

You can use /def/foo{blabla} then!

catcode`/=0

def/abd{abd..}

/def/dosomethingstupid{Something not recommended because it looks weird!}



/abd

/dosomethingstupid



bye

An expl3 approach:

documentclass{article}

usepackage{xparse}

ExplSyntaxOn



char_set_catcode_escape:N /

NewDocumentCommand /Abc {} { abc }



ExplSyntaxOff

begin{document}

/Abc

end{document}

As I said: here be dragons!

Rather than redefine / to have the meaning of , you could use LuaLaTeX and (a) set up a function that changes all instances of / in the text to "on the fly" and (b) assign this function to the so-called process_input_buffer callback, which does its work at a very early stage of processing, before (La)TeX does any of its usual work.

Of course, if you do need a forward-slash symbol in your document, you can no longer enter it as /; instead, you'll need to write /slash.

% !TEX TS-program = lualatex

documentclass{article}

usepackage{luacode}

begin{luacode}

function slash2bslash ( line )

    return string.gsub ( line, "/", "\" )

end

luatexbase.add_to_callback ( "process_input_buffer", slash2bslash, "slash2bslash" )

end{luacode}



begin{document}

/section{Hello}

/section{Good-bye}

end{document}

The amstex.tex style file for Plain TeX had @ as “alternative escape” and this was also used in amslatex (the first port of AMS-TeX to LaTeX), but then abandoned when amsmath was issued.

In AMS-TeX one could type @>f>g> for what would be typed xrightarrow[g]{f} in amsmath (both labels were optional, so @>>> meant a right pointing arrow). The downside was that a literal @ had to be input as @@.

There was no interface for defining “@-commands”, but there is the at package by Mark Wooding that provides it (the documentation can be read with texdoc mdwtools, because this points to the first hit, which is exactly at.sty).

For instance, the package provides by default the @-command @/, whereby

@/some text in italics/

(note the matching slash at the end) is the same as typing

textit{some text in italics}

Also predefined is @@ for printing an @. Note that @? would be different from ?: if you do

atdef ?{`?}

newcommand?{QQ}

the output of @? would be different from ?.

Of course, one could replicate the code for allowing other prefix characters. The big downside is that the prefix character must be made into an active one. If you want to use =-commands, such as your proposed =acircum, then you can't type = in a math formula any more (well, you'd need to be very careful).

When amsmath was released, AMS thought carefully about @-commands and decided to withdraw them and they had very good reasons for. I'm not sure where =acircum could be easier for users than acircum. I'm inclined to believe that they'll be very confused, actually.

You just need to know that commands should be escaped and that the signal for this escape is . Remembering different escapes for different commands would be a nightmare. Possibly funny (I'm writing this answer on All Saints' Eve), but definitely not a good user interface.

Other suggested methods such as doing catcode`/=0 are quite different.

If you do

catcode`/=0

newcommand{/Abc}{whatever}

you can then call /Abc or Abc and this will produce exactly the same result (unless you also changed the category code of /). Of course, you cannot use / for printing a slash.

There are good reasons for using the backslash as escape. The character is seldom, if ever, used in running text. For the set theory operation there is the semantically meaningful command setminus (and also the command backslash for the symbol as an ordinary atom). No other character in the ASCII range is in the same situation; except possibly @ itself (barring its usage in email addresses). Indeed, there is a TeX format that uses @ and not as escape: it's texinfo, that's been used for decades for TeXing documentation in GNU info format.