E:\>perl -le "print 'foo baz'=~/(foo|foo|foo)\s(?{print qq(Got '$1')})ba[r]/ ? qq(Matches '$1') : 'No match!'"
Got 'foo'
Got 'foo'
Got 'foo'
No match!

E:\>perl -le "print 'foo baz'=~/(foo|foo|foo)\s(?{print qq(Got '$1')})bar/ ? qq(Matches '$1') : 'No match!'"
No match!