From: James Gray <james@...>
Date: 2009-08-07T23:58:04+09:00
Subject: Re: R1.9 mixed encoding in file

On Aug 7, 2009, at 9:47 AM, Vít Ondruch wrote:

> James Gray wrote:
>> On Aug 7, 2009, at 8:49 AM, Vít Ondruch wrote:
>>
>>> Hello
>>
>> Hello.
>>
>>> C:\enc>echo p 'zufällige_žluťoučký'.encoding > encoding.rb
>>> according to specified encoding.
>> The problem with an idea like this is that before your String is ever
>> created the code to create it must be read (correctly) by Ruby's
>> parser and formed into a proper String literal.  That would be
>> impossible to do if String literals could be in any random Encoding.
>
> Yes, I understand that you have to parse the file. However, if I am
> right, you still have to read the file binary in case you are looking
> for some encoding directive on top of file.

You don't really have to:

$ cat source_encoding.rb
# encoding: UTF-8

output = ""
open(__FILE__, "r:US-ASCII") do |source|
   first_line = source.gets
   if first_line =~ /coding:\s*(\S+)/
     source.set_encoding($1)
   else
     output << first_line
   end
   output << source.read
end
p [output.encoding, output[0...20] + "…"]
$ ruby_dev source_encoding.rb
[#<Encoding:UTF-8>, "\noutput = \"\"\nopen(__…"]

James Edward Gray II