Bug #5696: rexml BaseParser uses instance_eval unnecessarily on listener add

• Status: Closed
• Assignee: -
• Target version: 1.9.3
• ruby -v: trunk

[headius (Charles Nutter)]

In add_listener in REXML::BaseParser, there's code to instance eval and replace the old "pull" method with a new one that calls all listeners. I assume this was done to avoid the cost of calling .each on the listeners when there's none registered, but when the list is empty this call is nearly a no-op anyway. The singletonizing effect of instance_eval and the redefinition of #pull, on the other hand, cause a cache flush throughout the system.

I have created a patch that removes the instance_eval, initializes the listeners array unconditionally, and does the event #each unconditionally. It passes all tests, and should perform better because it's not damaging the cache.

https://gist.github.com/1420383

This can be safely backported to any Ruby version and has no visible behavior change.

[ayumin (Ayumu AIZAWA)]

• Status changed from Open to Closed
• % Done changed from 0 to 100

This issue was solved with changeset r34202.
Charles, thank you for reporting this issue.
Your contribution to Ruby is greatly appreciated.
May Ruby be with you.

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• lib/rexml/parsers/baseparser.rb: rexml BaseParser uses
  instance_eval unnecessarily on listener add.
  patch from Charles Nutter. [Bug #5696] [ruby-core:41437]