Bug #1681: Integer#chr Should Infer Encoding of Given Codepoint

• Status: Closed
• Assignee: -
• Target version: -
• ruby -v: ruby 1.9.2dev (2009-06-21 trunk 23774) [i686-linux]

[runpaint (Run Paint Run Run)]

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String#ord and Integer#chr are symmetrical operations on ASCII Strings:

 'a'.ord.chr   #=> "a"

But Integer#chr fails to round-trip when the given codepoint is outside the range of ASCII:

 "\u{2563}".ord.chr #=> RangeError: 9571 out of char range

To fix this, the codepoint's encoding needs to be specified:

 "\u{2563}".ord.chr('utf-8')  #=> "╣"

This seems needlessly verbose given that Ruby already knows that my source encoding is UTF-8. I suggest, then, that, when invoked with no argument, Integer#chr displays the given codepoint w.r.t to the current encoding, raising a RangeError only if the codepoint is out-of-bounds for this inferred encoding.
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[nobu (Nobuyoshi Nakada)]

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Hi,

At Wed, 24 Jun 2009 06:42:29 +0900,
Run Paint Run Run wrote in [ruby-core:23997]:

This seems needlessly verbose given that Ruby already knows
that my source encoding is UTF-8.

It's irrelevant to source encoding. A possiblity would be
Encoding.default_internal?

--
Nobu Nakada

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[runpaint (Run Paint Run Run)]

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This seems needlessly verbose given that Ruby already knows
that my source encoding is UTF-8.

It's irrelevant to source encoding.  A possiblity would be
Encoding.default_internal?

Indeed; my mistake. :-)

--
Run Paint Run Run

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[matz (Yukihiro Matsumoto)]

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Hi,

In message "Re: [ruby-core:24001] Re: [Bug #1681] Integer#chr Should Infer Encoding of Given Codepoint"
on Wed, 24 Jun 2009 09:54:06 +0900, Run Paint Run Run [e-mail] writes:
|
|>> This seems needlessly verbose given that Ruby already knows
|>> that my source encoding is UTF-8.
|>
|> It's irrelevant to source encoding.  A possiblity would be
|> Encoding.default_internal?
|
|Indeed; my mistake. :-)

Source encoding may be different from default internal encoding.
Since codepoint number does not contain any encoding information,
there's information loss. I am not sure it is OK to use possibly
wrong encoding information (default internal), even as a default.

I'd like to hear opinion from others.

						matz.

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[duerst (Martin Dürst)]

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We have String#encode (without any arguments), which transcodes to
default_internal (and in addition, doesn't raise an exception for
invalid byte sequences,..., which may be a security issue), so I don't
think using Integer#chr with a default encoding of default_internal
would be such a big problem.

Regards, Martin.

On 2009/06/25 18:06, Yukihiro Matsumoto wrote:

Hi,

In message "Re: [ruby-core:24001] Re: [Bug #1681] Integer#chr Should Infer Encoding of Given Codepoint"
on Wed, 24 Jun 2009 09:54:06 +0900, Run Paint Run [e-mail] writes:
|
|>> This seems needlessly verbose given that Ruby already knows
|>> that my source encoding is UTF-8.
|>
|> It's irrelevant to source encoding. A possiblity would be
|> Encoding.default_internal?
|
|Indeed; my mistake. :-)

Source encoding may be different from default internal encoding.
Since codepoint number does not contain any encoding information,
there's information loss. I am not sure it is OK to use possibly
wrong encoding information (default internal), even as a default.

I'd like to hear opinion from others.

 					matz.

--
#-# Martin J. Dürst, Professor, Aoyama Gakuin University
#-# http://www.sw.it.aoyama.ac.jp mailto:[e-mail]

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[matz (Yukihiro Matsumoto)]

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

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Applied in changeset r23865.
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