Re: don't want to display yyout

[Vincent Zweije]

On Wed, May 18, 2005 at 10:08:09PM +0200, Hans Aberg wrote:

||  At 13:22 -0400 2005/05/18, Aaron Jackson wrote:
||  >On May 18, 2005, at 4:46 AM, Nicolas Peyrussie wrote:
||  >>I am using flex and don't want to see yyout as output.
||  >>The only way I found to sort it out was to redirect yyout
||  >>to a file (out.txt), but I don't think it is a really
||  >>good idea to do that.
||  >>
||  >>Do you know if I can just say 'I don't want to see the
||  >>output' in Flex ?
||  >
||  >The flex man page says:
||  >
||  >The scanner writes its ECHO output to the yyout global
||  >(default, std-out), which may be redefined by the user
||  >simply by assigning it to some other FILE pointer.
||
||  I think Flex imnplements a default rule
||     .  ECHO
||  which can be overriden by writing
||     .  { /* whatever you like */ }

True.

However, if you hit your default rule, that means that your
token definitions didn't cover all possible input.  For some
applications, that's a BAD thing.

If so, find the holes in your token definitions, and plug them.

I like to use %option nodefault precisely for that reason.

Ciao.                                                  Vincent.