Findings on '%q' formatting and documentation

[Asko Kauppi <askok@...>]

In doing serialization code using Lua/C API, I found two things  
concerning the '%q' formatting used in string.format():

* There is no Lua/C API way to convert a string into its safe, '%q'  
formatted representation.

- string.format code (in lstrlib.c) has 'static' scope for the  
functions involved
- lua_pushfstring() could support '%q' but it's conceptually in wrong  
level (no luaL functions in core)

I would suggest adding serialization/deserialization right into the  
Lua/C API itself, this would cover the '%q' case as well (serialize a  
string and you get its '%q' conversion).


* The second finding concerns documentation:

http://www.lua.org/manual/5.1/manual.html#pdf-string.format

states: "This function does not accept string values containing  
embedded zeros."

should be: "This function does not accept format strings and %s  
parameters containing embedded zeros."

Having embedded zeros in '%q' parameters is okay (they convert to \000).

-asko