Re: String constant concatenation in c-lex.c

["Zack Weinberg" <zackw at Stanford dot EDU>]

On Thu, Jun 21, 2001 at 03:35:49PM -0700, Stan Shebs wrote:
> 
> Hmmm.  @"" is basically an object constructor, while I think of
> string concatenation as lower-level, so it doesn't seem as sensible
> to mimic L prefix behavior.  It feels almost like having a function
> call in the middle of a pile of constant args.  I wouldn't even mind
> only allowing the middle case, but there would almost certainly be a 
> compat problem if the first case were disallowed.
> 
> Since there's no ObjC committee to debate this endlessly :-), how
> about we make our users happy and go with the L prefix rule anyway,
> so an @ anywhere in a group of concatenated strings will cause the
> result to be an @-string.  If that's going to be extra work to
> implement, I'll be glad to help.

I tried to implement this yesterday and ran afoul of another rule:

#define STRING "whatever"
...
NXConstantString str = @STRING;

is valid.  This forces the initial @ to be a separate token from the
string constant, and that means everything I've tried causes there to
be a communications mess between cpplib, c-lex.c, and the parser.

We also run into a can of worms with e.g. @"foo" L"bar"...
NXConstantString doesn't handle wide string literals, right?

I'm tempted to push the entire mess off and leave concatenation of
@-strings in the parser.  That will mean the syntax of a string
literal object is

   '@' STRING+ ('@' STRING+) *

since @ "foo" "bar" "baz" will be converted to @ "foobarbaz" by the
lexer.  Can you live with this at least transitionally?

-- 
zw    This notion of the domain specificity of information is, patently, of
      no use to anybody.  I mention it simply to get it out of the way.
      	-- Jerry Fodor, _The Mind Doesn't Work That Way_