From: Zev Blut <rubyzbibd@...>
Date: 2006-12-19T15:34:37+09:00
Subject: Strategies for writing Ruby applications to be easily distributed with RubyGems

Hello,

This is mostly a repost of ruby-talk[229723] with some clarifications
and an appeal for ideas.

I have recently attempted to write a RubyGem for the Saikuro project.
Unfortunately, I have learned that there is a mismatch between how I
wrote Saikuro and how RubyGems expects executables to work.

I would like to know is are there any better or commonly followed ways
of writing executables that work with RubyGems and other installation
programs such as setup.rb ?

Below are the differences between how I wrote Saikuro and what
RubyGems does.

1)
Saikuro uses the "if __FILE__ == $0" check before doing the
"application work".  When RubyGems creates a new gemified saikuro
wrapper to call the real saikuro bin "$0" is the gemified saikuro and
not the real one.  Thus, by default nothing happens.

For fun I cheated and commented out the "if __FILE__" check and
replaced it with "if true".  Saikuro will work with this change, but I
then ran "saikuro -?" to get a usage message and found the next
problem:


2)
I was reading through the Programming Ruby book and found a part that
showed how to use rdoc to create usage messages.  I figured this might
be better than my normal technique so I used it in Saikuro.  This has
caused a number of problems actually.

* With the above cheat I get the gem message:
--
/usr/bin/saikuro: invalid option -- ?
This file was generated by RubyGems.

The application 'Saikuro' is installed as part of a gem, and this file
is here to facilitate running it.
--

Which is not the usage message I wanted.


My original goal was to keep Saikuro simple so that as a single file
nothing complicated was needed.  But now I suppose that should change.

I am planning to move all logic above and "if __FILE__ == $0" block
into a separate library file.  Then add a require to this newly made
file and remove the "if __FILE__" check logic to make the insides of
the block automatically run.

Next I will stop using rdoc usage and simply put the usage message in
a method that outputs a String.

Does this sound like a good strategy?

Thanks,
Zev