Fellow monks,

Here is my problem : I want to substitute a word, 'foo', by another word 'bar' in a line, but only if that line does not contain 'toto' before matching 'foo'.

Of course, I can do this :

while (<DATA>) {
  s/foo/bar/ if ($_ !~ /toto.*?foo/);
  print;
}

__DATA__
toto 4dsf4qsd foo
mama 432fz foo
[download]

Output:

toto 4dsf4qsd foo
mamaf 432fz bar
[download]

But what I am looking for is an only regex, probably using look-behing assertion. I have played with (?<!pattern), without success. As far as I understand, the problem is that there can be anything between 'toto' and 'foo'.

Any hint ?

--
zejames