From: Nathaniel Talbott <ntalbott@...>
Date: 2001-09-22T08:22:16+09:00
Subject: [ruby-talk:21504] Replacement for __FILE__ == $0

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OK, this will probably end up being an RCR, but first I want to get some
feedback. Does this construct bother anybody else?:

	if __FILE__ =3D=3D $0
		... Do stuff ...
	end

'Cause it bothers me. Here's what bothers me about it:
1) It looks ugly. It's just my personal opinion, but it violates my =
sense of
aesthetics.
2) It doesn't communicate. When I first saw it in a file, I thought, =
"What
in the world are they doing here!" It looked like some kind of black =
magic.
It seems to violate the "Principle of Least Research," which means that =
for
most things Ruby, I don't even have to look up what a construct is =
doing,
it's just obvious.
3) It's duplicated code between each file that uses it. OK, so not very
much, but one could type the wrong global or something and not get the
expected results.
4) It uses two globals. 'Nuff said.

Obviously this is useful functionality, and I can envision a really =
nifty
replacement. There are two things I'm lacking, though: a name, and an
implementation. Here's how I'd like it to behave:

	run_if_start_file {   # This name makes me gag! Help!
		puts "I will only print if this file is the file ruby was
started with"
	}

Does that express intent better? Is it more "Ruby?"

Clearly implementation is problematic, since this won't work unless it's
defined in the file you're wanting to use it for, which kind of defeats =
the
purpose:

	def run_if_start_file
		if __FILE__ =3D=3D $0
			yield
		end
	end

So if someone has a better name and/or implementation, I'd love to =
submit
this as an RCR. I'll keep mulling it over myself, too.


Nathaniel

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