From: "naruse (Yui NARUSE)" <naruse@...>
Date: 2012-11-12T14:29:23+09:00
Subject: [ruby-core:49245] [ruby-trunk - Bug #7201] Setting default_external affects STDIN encoding but default_internal does not


Issue #7201 has been updated by naruse (Yui NARUSE).


brixen (Brian Ford) wrote:
> Can someone please explain how the inconsistency with how the rest of IO instances would behave with transcoding is not a bug? 

This is because IO object's internal property are set when it is created.
In this case, STDIN's internal property is not changed when default_external and default_internal are set.

And in this situation, STDIN.external_encoding returns current Encoding.default_external,
so it looks as if Encoding.default_external changes STDIN.

Following are detail

= IO's internal property

An IO object has two internal properties, extenc (external encoding) and intenc (internal encoding).

When extenc and intenc are explicitly given like open("foo.txt", "r:UTF-8:ISO-8859-1"),
extenc is UTF-8 and intenc is ISO-8859-1

When extenc and intenc are not given like open("foo.txt", "r") or STDIN without -E/-U,
extenc is nil and intenc is nil.

= IO#external_encoding

If extenc is not nil, returns extenc.
If extenc is nil, returns current Encoding.default_external.

This method is to know what encoding is set on io.read.
(this had to be always return extenc...)

= IO#internal_encoding

Returns intenc.

= Conclusion

Current inconsistency is derived from IO objects' internal state and settings for conversion.
The change will need add more internal property and breaking IO#external_encoding.
I couldn't design better one yet.
----------------------------------------
Bug #7201: Setting default_external affects STDIN encoding but default_internal does not
https://bugs.ruby-lang.org/issues/7201#change-32804

Author: brixen (Brian Ford)
Status: Rejected
Priority: Normal
Assignee: naruse (Yui NARUSE)
Category: 
Target version: 2.0.0
ruby -v: ruby 1.9.3p286 (2012-10-12 revision 37165) [x86_64-darwin10.8.0]


Changing Encoding.default_external changes STDIN.external_encoding, but changing Encoding.default_internal does not change STDIN.internal_encoding.

STDOUT and STDERR internal/external encodings are not changed in either case and are always nil.

Is this a bug? See the following IRB transcript:

$ irb
1.9.3p286 :001 > Encoding.default_external
 => #<Encoding:UTF-8> 
1.9.3p286 :002 > Encoding.default_internal
 => nil 
1.9.3p286 :003 > STDIN.external_encoding
 => #<Encoding:UTF-8> 
1.9.3p286 :004 > STDIN.internal_encoding
 => nil 
1.9.3p286 :005 > Encoding.default_external = "euc-jp"
 => "euc-jp" 
1.9.3p286 :006 > STDIN.external_encoding
 => #<Encoding:EUC-JP> 
1.9.3p286 :007 > STDIN.internal_encoding
 => nil 
1.9.3p286 :008 > Encoding.default_internal = "iso-8859-1"
 => "iso-8859-1" 
1.9.3p286 :009 > STDIN.internal_encoding
 => nil 

Thanks,
Brian





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