From: noreply@...
Date: 2007-05-30T10:52:04+09:00
Subject: [ ruby-Bugs-3329 ] String#scan loops forefever if scanned string is modified inside block.

Bugs item #3329, was opened at 2006-01-26 00:55
You can respond by visiting: 
http://rubyforge.org/tracker/?func=detail&atid=1698&aid=3329&group_id=426

Category: Language / Runtime / Core Libraries
Group: None
>Status: Closed
>Resolution: Accepted
Priority: 3
Submitted By: Nikolai Lugovoi (meadow)
Assigned to: Nobody (None)
Summary: String#scan loops forefever if scanned string is modified inside block.

Initial Comment:
ruby 1.8.4 (2005-12-24)

Following code loops infinitely:

a = " 12345678 "; a.scan(/\d/) {|s| a[3,2]='test';  s} 

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>Comment By: Ryan Davis (zenspider)
Date: 2007-05-29 18:52

Message:
confirmed.

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Comment By: Daniel Berger (djberg96)
Date: 2007-05-29 16:47

Message:
This was fixed by freezing the yielded object as per ruby-core: 7222. Trying to run the sample code with 1.8.6 raises a RuntimeError.

Dan

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Comment By: Paul Duncan (pabs)
Date: 2006-01-26 12:33

Message:
I've posted a comment this on ruby-core at the following URL:

http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-core/7220

Basically, I'm not convinced the "fix" to this problem is better than just leaving things as-is.  My suggestion, and patch, is a clarification in the documentation that discourages people from modifying the receiving string inside a String#scan block.

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You can respond by visiting: 
http://rubyforge.org/tracker/?func=detail&atid=1698&aid=3329&group_id=426