[Slightly OT] Case against ".*" regexp

[Edgardo Hames]

Some time ago I remember reading a post in this list against using
".*" regexp but I cannot find it -- I guess I don't remember the right
keywords
Does anyone remember that?

Thanks a lot,
Ed
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[Giles Bowkett]

I didn't see that, but the .* regex can easily misfire. There's a
great book on this called "Mastering Regular Expressions" from
O'Reilly. The author's name I think is Jeff Friedl.

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Giles Bowkett
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[Robert Klemme]

Some time ago I remember reading a post in this list against using
".*" regexp but I cannot find it -- I guess I don't remember the right
keywords
Does anyone remember that?

Not exactly. But you should not use ".*" nested in another starred
expression because that will usually lead to massive backtracking.
Another problem is, that ".*" matches the empty string which is often
not what you want.

Kind regards

robert

 

[Jan Friedrich]

Some time ago I remember reading a post in this list against using
".*" regexp but I cannot find it -- I guess I don't remember the right
keywords

Did you probably mean this thread?
http://www.ruby-forum.com/topic/100364

regards
Jan

 

[Brian Candler]

Not exactly. But you should not use ".*" nested in another starred
expression because that will usually lead to massive backtracking.
Another problem is, that ".*" matches the empty string which is often
not what you want.

And also eats as much string as it can without causing the regexp to fail -
*? is the non-greedy form.

 

[Robert Dober]

Did you probably mean this thread?
http://www.ruby-forum.com/topic/100364

Hmm I am not sure this one was what OP meant, was there not a problem
with the greedy match eating up "<" s in xml/html

if I remember correctly OPITOP (OP in the other post asked why

%r{(<.*>)*} === "<a><b><c>"

regards
Jan

HTH
Robert