Special characters in patterns: what about \?

[Frank Küster <frank@...>]

Hi,

is this a bug or am I misunderstanding anything?  According to the
reference manual, 

,----
| x: (where x is not one of the magic characters ^$()%.[]*+-?)
|    represents the character x itself.
`----

so \ is not mentioned as a special character.  However, in the "not set"
pattern [^\] it seems to "escape" the closing square bracket:

***********************
#!/usr/bin/lua

function deluaficate(oldpat)
   local newpat
   newpat = string.gsub(oldpat,'([^\])%-','%1%%%-')
   print (newpat)
   return newpat
end

deluaficate('lm-hist')
***********************

    (this is supposed to be the first step in using a user-supplied
    filename, which might contain a hyphen, as a pattern for
    string.match(); I want to give power users full access to lua patterns,
    therefore '\-' should not be replaced). 

Surprisingly, this gives:

$ ./deluaficate 
/usr/bin/lua: ./deluaficate:5: malformed pattern (missing ']')
stack traceback:
	[C]: in function 'gsub'
	./deluaficate:5: in function 'deluaficate'
	./deluaficate:10: in main chunk
	[C]: ?
~$ lua -v
Lua 5.1.2  Copyright (C) 1994-2007 Lua.org, PUC-Rio


What am I missing?

Regards, Frank

-- 
Frank Küster
Single Molecule Spectroscopy, Protein Folding @ Inst. f. Biochemie, Univ. Zürich
Debian Developer (teTeX/TeXLive)