The word boundary does not help, because for instance 'FOOBAR X' and 'FOOBARX' are both strings which should be accepted (because both BAR X and BARX are considered different from <BAR>), while 'FOOBAR' should be rejected.

Actually I meanwhile believe to having found a solution to my problem while having lunch (it is surprising how a glass of Italian Chardonnay can do good to the brain cells): 

$name =~ /^FOO(?!(BAR|BAZ)$)/

[download]
so unless someone can find a flaw with this (the examples where I tried it, worked so far), I think I will stick with it. It is not a beautiful solution, though, because if I would like one day to pick up what is to the right of FOO, I can't do it. So I'm still interested in hearing alternative proposals.

Maybe just to make it clear, here are concrete examples: The following strings should be accepted: 

FOOABC
FOO_BAR
FOOBA
FOOBAZZZZ
FOOBAR BAZ

[download]
while the following should be rejected: 
FOOBAR
FOOBAZ
BARBAZ

[download]
-- 
Ronald Fischer <ynnor@mm.st>

In reply to Re^3: Zero-width look-ahead regexp question by rovf
in thread Zero-width look-ahead regexp question by rovf

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