Re: Encoding::primary_encoding

Dirk Traulsen wrote:
> Am 23 Oct 2007 um 4:26 hat David Flanagan geschrieben:

>> Here's a section from chapter 2 of my forthcoming book. 
> (..)
>> 	<para>
>> 	  More generally, however, you can identify the encoding of a
>> 	  Ruby file by placing a special comment on the first (or
>> 	  second: see below) line of the Ruby file.  The comment must be
>> 	  written entirely in ASCII, and must include the string
>> 	  "coding" 
> 
> So the vim modeline
> # vim: fenc=utf-8
> will not be recognized?

Correct. Ruby follows Python in this.  See 
http://www.python.org/dev/peps/pep-0263/ for Python's details.


> 
> Two comments: 
> 1.
> You speak of vi users and used vim: in the modeline.
> This is not necessary in vim. Vim recognizes equally 'vi:', 'vim:' and 
> even 'ex:'. For your readers it might be more consistent to use only vi 
> or vim, IF Ruby will recognize both or ignore them completely, which I 
> don't know.

Thanks for this feedback.  I'm an emacs user, as you might have guessed, 
so I was just quoting the example from the python docs.  Ruby doesn't 
care what the prefix is, so I'll change that to vi.

> 2.
> You're modeline example is no valid modeline in vim.
> There are two forms of modelines in vim:
> a. One with implicit, but not mentioned command 'set' and
> b. one with the command 'set' spelled out.
> In case a. it reads the complete line, so nothing else is allowed 
> there.
> In case b. which you used, there MUST be a colon ending the command, 
> which also allowes to add comments after the command:
> 
> # vi: set fileencoding=utf-8: #This sets the encoding for Ruby also!
> (or in c: /* vi: set fileencoding=utf-8 : */ )


I've added the colon in my example, and I now see that it is there in 
the Python document refereced above, too.

>> 	<para>
>> 	  An encoding comment like that shown above is usually only
>> 	  valid on the first line of the file.  It may appear on the
>> 	  second line, however, if the first line is a "shebang" comment
> 
> Modelines are by default recognized by vim in the first and last 5 
> lines of a file. Do you know whether this is true for Ruby also? Does 
> Ruby recognize modelines at least in the last line too, where they are 
> mostly?

No; it can't.  The parser needs to be able to find the comment right at 
the start of the file so it knows how to interpret the rest of the file. 
  Again, Ruby follows Python in this regard.

> Dirk

	David