From: Brian Candler <b.candler@...>
Date: 2009-02-23T22:12:23+09:00
Subject: Re: encoding problem with tr() and hash keys

Do One wrote:
> Please help to understand solution to this problem (ruby 1.9.1):
> 
> In utf-8 environment I do:
> 
> irb(main):121:0> h = {"a" => 1, "\u0101" => 2}
> => {"a"=>1, "ā"=>2}
> irb(main):122:0> h.key? "a".tr("z", "\u0101")
> => false <--- wrong!
> irb(main):123:0> h.key? "\u0101".tr("z", "\u0101")
> => true

Perhaps describe your environment in more detail? It works for me:

$ irb19
irb(main):001:0> h = {"a" => 1, "\u0101" => 2}
=> {"a"=>1, "ā"=>2}
irb(main):002:0> h.key?("a")
=> true
irb(main):003:0> h.key?("\u0101")
=> true
irb(main):004:0> h.key?("a".tr("z", "\u0101"))
=> true
irb(main):005:0> h.key? "a".tr("z", "\u0101")
=> true
irb(main):006:0> h.key? "z".tr("z", "\u0101")
=> true
irb(main):007:0>

This is Ubuntu Hardy, ruby 1.9.1 (2008-12-01 revision 20438) 
[i686-linux] compiled from source. I think this is 1.9.1-preview2 rather 
than 1.9.1-p0.

To eliminate problems with encoding, maybe try writing this as a script 
and running it from the command line:

p h = {"a" => 1, "\u0101" => 2}
p h.key?("a")
p h.key?("\u0101")
p h.key?("a".tr("z", "\u0101"))
p h.key? "a".tr("z", "\u0101")
p h.key? "z".tr("z", "\u0101")

   ruby19 test.rb
   ruby19 -Ku test.rb
   ruby19 --encoding UTF-8:UTF-8 test.rb

to see if this makes any difference. On my machine at least, the -K and 
--encoding flags are not recognised by irb.
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