[ruby-core:58977] [ruby-trunk - Feature #8977][Assigned] String#frozen that takes advantage of the deduping

Issue #8977 has been updated by tmm1 (Aman Gupta).

Status changed from Open to Assigned
Assignee set to matz (Yukihiro Matsumoto)

I just made some more arguments for this feature in #9229.

The goal here is to provide runtime access to the frozen string literal table.
This is not a new idea. For instance, see String.Intern in .NET: http://msdn.microsoft.com/en-us/library/system.string.intern(v=vs.110).aspx

@samsaffron also made a good point above: older versions and other implementations of ruby can easily provide their own implementations of String#frozen:

> It also could be implemented using weak refs in 2.0 and stubbed with a .dup.freeze in 1.9.3 . 

@ko1 also agrees with the feature above:

>  I can accept the way to get the string which we can get "foo"f dynamically.

So the remaining question (as always) is a naming issue.
I like String#frozen, but maybe there is some argument that it can be confused with #freeze.

@matz Do you approve of String#frozen, or do you have some other preference? Other proposals are:

  String#dedup
  String#pooled
  String::frozen(str)

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Feature #8977: String#frozen that takes advantage of the deduping 
https://bugs.ruby-lang.org/issues/8977#change-43529

Author: sam.saffron (Sam Saffron)
Status: Assigned
Priority: Normal
Assignee: matz (Yukihiro Matsumoto)
Category: 
Target version: current: 2.1.0


During memory profiling I noticed that a large amount of string duplication is generated from non pre-determined strings.

Take this report for example https://gist.github.com/SamSaffron/6789005 (generated using the memory_profiler gem that works against head) 

">=" x 4953
    /Users/sam/.rbenv/versions/2.1.0-dev/lib/ruby/2.1.0/rubygems/requirement.rb:93 x 4535

This string is most likely extracted from a version. 

Or 

"/Users/sam/.rbenv/versions/2.1.0-dev/lib/ruby/gems" x 5808
    /Users/sam/.rbenv/versions/2.1.0-dev/lib/ruby/gems/2.1.0/gems/activesupport-3.2.12/lib/active_support/dependencies.rb:251 x 3894

A string that can not be pre-determined. 

---- 


It would be nice to have 

"hello,world".split(",")[0].frozen.object_id == "hello"f.object_id 

Adding #frozen will give library builders a way of using the de-duping. It also could be implemented using weak refs in 2.0 and stubbed with a .dup.freeze in 1.9.3 . 

Thoughts ?  





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