From: Cezary <cezary.baginski@...>
Date: 2011-06-10T23:03:20+09:00
Subject: [ruby-core:36935] Re: [Ruby 1.9 - Feature #4824] Provide method Kernel#executed?

On Fri, Jun 10, 2011 at 07:20:32AM +0900, Rocky Bernstein wrote:
>
> Issue #4824 has been updated by Rocky Bernstein.
>
>
> Cezary Baginski wrote:
> > This may seem like heresy, but isn't really:
> >
> >   __FILE__ == $0
> >
> > just a hack for letting a file be *both* a script and a "library"
> > at the same time? With the only sane use (I can think of) being
> > adding unit tests?
>
> I wrote my thoughts regarding this to ruby-core on June 5-6. See
> http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-core/36772.

Yes, I read your comments (I read the list). It was what got me
thinking. I didn't like checking using file path strings either.

> It has one answer to your question which, in sum, is "demo code".
> Demonstration code is not the same as a unit test.

Yes, but shouldn't that be in a README or example.rb instead?

> But there is another use. One can write a program that has a
> command-line interface, but folks can use this as a library instead.
> For example see, https://github.com/rocky/ps-watcher

Shouldn't there be an executable script installed in bin/ loading a
lib/ps-watcher/cli.rb file ? It would be accessible from $PATH.
And unit/integration tests can be simpler and more robust.

I understand the use case(s), but I don't see why '__FILE__ == $0' is
really that useful and good practice enough to be explicitly supported
by the language.

As for the name - anything containing 'main' assumes familiarity with
C-type languages, which may or may not be the case for novices.

--
Cezary Baginski