Feature #19191
openImplicit console input transcoding is more desirable
Description
In response to Bug #18353, STDIN.internal_encoding are set and encoding is converted explcitly on Windows platform.
For example, [STDIN.external_encoding, STDIN.internal_encoding] # => [Encoding::Windows-31J, Encoding::UTF-8]
if STDIN is console.
I feel that internal_encoding should be reserved for specific applications. And I think setting internal_encoding to STDIN is not foreseened.
Today I found irb breaks STDIN encoding, like
>ruby -rirb -e "p [$stdin.external_encoding, $stdin.internal_encoding]; IRB.setup(''); IRB::Irb.new(); p [$stdin.external_encoding, $stdin.internal_encoding]"
[#<Encoding:Windows-31J>, #<Encoding:UTF-8>]
[#<Encoding:UTF-8>, nil]
We know input has console code page encoding. So we always can convert encoding from console code page to io_input_encoding().
proposal¶
when reading from console on Windows, input encoding is enfoced to console code page and encoding conversion is implicitly applied.
when set_encoding("UTF-8")
implicitly converts console code page to UTF-8.
when set_encoding("CP437", "UTF-8")
implicitly converts console code page to UTF-8. external_encoding is ignored.
binmode or binary input method is not affected by these specifications.
set_encoding, etc. will continue to work as before, and this specification will affect only when encoding conversion on read (NEED_READCONV() and make_readconv()).
Updated by Eregon (Benoit Daloze) almost 2 years ago
YO4 (Yoshinao Muramatsu) wrote:
when
set_encoding("UTF-8")
implicitly converts console code page to UTF-8.
I'm against more inconsistent corner cases like this for set_encoding
.
Probably IRB should be fixed here to inherit the original $stdin
external and internal encodings?
Updated by YO4 (Yoshinao Muramatsu) almost 2 years ago
I agree that the IRB issue should be corrected on the part of the IRB.
My point was that for certain devices, external_encoding on read can be fixed to the device's specification.
In that case, external_encoding is not used when internal_encoding is specified,
and if only external_encoding is specified, it is treated as a conversion from device_encoding to external_encoding.
Input from the console will be treated as locale encoding.
Updated by YO4 (Yoshinao Muramatsu) almost 2 years ago
Not sure if this is appropriate for this topic,
Consider the case where UTF-16 reading from the console will be supported in the future.
For explicit encoding
p [STDIN.external_encoding, STDIN.internal_encoding]
=> ["UTF-16LE", "UTF-8"].
For implicit encoding
p [STDIN.external_encoding, STDIN.internal_encoding]
=> ["UTF-8", nil].
And I think the console output implicitly uses UTF-16LE as device encoding.