From: akr@...
Date: 2015-08-23T02:13:11+00:00
Subject: [ruby-core:70552] [Ruby trunk - Feature #11473] Immutable String	literal in Ruby 3

Issue #11473 has been updated by Akira Tanaka.


Yusuke Endoh wrote:
> Why do matz and akr want to make String literals immutable, at first?  Please explain use case.

My first intent is explained at:
https://bugs.ruby-lang.org/issues/8976
This is refered from this issue as a related ticket.

At the meeting (DevelopersMeeting20150820Japan), matz decided by Matsuda-san's argument.
Matsuda-san explains his motivation in
https://bugs.ruby-lang.org/issues/8976#note-30

In short, current situation frustrate developers, especially library developers.
The problem is caused by an ambivalent between clean code and fast code.

> For performance?  Is it more important than usability, in the recent Ruby design?

This issue tries to match performance (fast code) and usability (clean code).

I agree more code (dup, String.new or something new) is required to distinguish
string modifiable from string never modified.
It decline usability.
However it prevents unintentional string modification.
This can improve usability.
So, total usability changes are not trivial.

However if code bloat is small enough, latter (usability improvement) should win.

In my experiment, modification is about one per 700 lines.
I feel the usability decline is acceptable.

My experiment is here:
https://github.com/akr/ruby/tree/frozen-string

```
% git diff -U0 trunk lib/**/*.rb|grep '^+'|grep -v '^+++'|wc
    256    1273   10887
% wc lib/**/*.rb|tail -1
 175569  537606 4639935 total
```

So, the library modification rate is one per 175569/256=685.8 line.



----------------------------------------
Feature #11473: Immutable String literal in Ruby 3
https://bugs.ruby-lang.org/issues/11473#change-53960

* Author: Koichi Sasada
* Status: Assigned
* Priority: Normal
* Assignee: Yukihiro Matsumoto
----------------------------------------
Matz said "All String literals are immutable (frozen) on Ruby 3".

This ticket is place holder to discuss about that.




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