From: Tim Pease <tim.pease@...>
Date: 2007-07-03T03:21:44+09:00
Subject: Re: getting rid of $0

On 7/2/07, Alex Young <alex@blackkettle.org> wrote:
> Tim Pease wrote:
> > On 7/2/07, Michel Demazure <michel@demazure.com> wrote:
> >> The common idiom
> >>  if __FILE__ == $0 then ...
> >> gives bugs when $0 is not what one would expect, for instance under a
> >> debugger, or in rubyscript2exe, etc.
> >>
> >> There should be a primitive test
> >>    if <nice name to be found> then...
> >>
> >
> > require 'English'
> >
> > if __FILE__ == $PROGRAM_NAME
> >  ...
> > end
> >
> Does that solve the problem?  Isn't that vulnerable to the same issues
> as just using $0?
>

You're correct! That does not solve the problem. :/

Hmmm ... the solution I use most often is to have a top-level function
that runs the application.  This top-level function is called by a
separate Ruby script.


class MyApp
  def self.run( args )
    new(args).run
  end
  ...
end

And in an executable file called "my_app"

#!/usr/bin/env ruby

require 'MyApp'
MyApp.run ARGV


I try to avoid the __FILE__ == $0 idiom when I distribute code. You
run into the problems the original poster pointed out, and rubygems
also wrappers up all your executables with it's own special calling
semantics (provides compatibility between windows / *nix).

Not the answer you want to hear, but, "don't do that".  Sorry :/

TwP