From: naruse@...
Date: 2015-12-17T16:39:47+00:00
Subject: [ruby-core:72218] [Ruby trunk - Bug #11827] StringIO with set_encoding broken with enabled frozen string literal

Issue #11827 has been updated by Yui NARUSE.


deepj # wrote:
> Shugo Maeda wrote:
> > 
> > What behavior do you expect?
> 
> Not throw the exception in this case. I guess this is a better example https://github.com/rack/rack/blob/master/lib/rack/mock.rb#L139
> 
> Here is set an encoding for IO classes included StringIO. When the frozen string literal is enabled it causes a problem obviously. And there is no way (at least I haven't figured out it) how to change an encoding for a StringIO with frozen string. For me it wouldn't be any difference with I have a StringIO with a frozen string, or a File. It's just a interface with same expected behavior of IO-like classes. In this case a change of encoding. So a string would be mutable in StringIO when it was immutable previously. I might be wrong here.

In this case `''.force_encoding(Encoding::ASCII_8BIT)` should be `String.new.force_encoding(Encoding::ASCII_8BIT)`
(or String.new(encoding: Encoding::ASCII_8BIT) for Ruby 2.3)

Away from the case and thinking ideal behavior, StringIO should be a view of given source string and set_encoding shouldn't change source encoding.
But I'm not sure that it is worth breaking the compatibility.

----------------------------------------
Bug #11827: StringIO with set_encoding broken with enabled frozen string literal
https://bugs.ruby-lang.org/issues/11827#change-55627

* Author: deepj #
* Status: Feedback
* Priority: Normal
* Assignee: 
* ruby -v: ruby 2.3.0preview2 (2015-12-11 trunk 53028) [x86_64-darwin15]
* Backport: 2.0.0: UNKNOWN, 2.1: UNKNOWN, 2.2: UNKNOWN
----------------------------------------
I'm not sure if this the following problem is an expected behavior. But I guess, it is a bug when I run the code below. It throws `set_encoding': can't modify frozen String (RuntimeError).

~~~
# frozen_string_literal: true

io = StringIO.new('')
io.set_encoding(Encoding::BINARY)
~~~

I wouldn't expect this kind of behavior.




-- 
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