Instead of just trusting the documentation I went and did my own tests on differences in regex assertions. Here are my results: 

dooberwah@kyle:~$ perl -e 'print "foobar" =~ /(?<=foo)bar/, "\n";'
1
dooberwah@kyle:~$ perl -e 'print "foobar" =~ /(?=foo)bar/, "\n";'

dooberwah@kyle:~$

[download]

As you can see, trying to use a look-ahead assertion in place of a look-behind assertion yealds no results. I certainly hope that we're still talking about the same thing. You got me a little confused with the jumping analogy :-). If your actually talking about something different please just tell me.

-Ben Jacobs (dooberwah)
http://dooberwah.perlmonk.org
"one thing i can tell you is you got to be free"

In reply to (dooberwa) I hold with beliefs that your regex is incorrect by dooberwah
in thread Regular Expression Tweaking by dooberwah

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