gem which cannot find gem despite it being installed

Question

Hi,
I've built my first gem but I don't seem to be able to get it to install correctly. I can issue the command

sudo gem install ceilingfish-toto

Which produces the output

Successfully installed ceilingfish-toto-0.3.6
1 gem installed

But when I then type gem which ceilingfish-toto. I get the output

Can't find ruby library file or shared library ceilingfish-toto

Which is very strange because if I go and look in my gems folder I can see all the files installed there

# ls -l /opt/local/lib/ruby/gems/1.8/gems/ceilingfish-toto-0.3.6/
total 48
-rw-r--r--  1 root  admin  1053 14 Feb 17:16 LICENSE
-rw-r--r--  1 root  admin  6166 14 Feb 17:16 README.md
-rw-r--r--  1 root  admin   879 14 Feb 17:16 Rakefile
-rw-r--r--  1 root  admin     6 14 Feb 17:16 VERSION
-rw-r--r--  1 root  admin  2477 14 Feb 17:16 ceilingfish-toto.gemspec
drwxr-xr-x  7 root  admin   238 14 Feb 17:16 test

Does anyone know what could cause this? I think it's complaining because there is a hyphen in the gem name. You can see the gemspec here http://github.com/ceilingfish/toto

Answer 1

gem which ceilingfish-toto looks through the gem require path for a file named ceilingfish-toto.rb. Since there isn't one, it returns nothing. What would work for you is gem which toto, but since lib/ is not included in your gem spec, the lib files are not installed, so it doesn't exist.

Rerunning rake gemspec might fix the problem.

As an aside, you can check whether a gem is installed by its name by using gem list ceilingfish-toto which should show you it is installed, regardless of the files it has(it will also list the versions installed).

Answer 2

OK, so the problem here appears to be that there was a problem with my gemspec file. From what I can tell there absolutely has to be a file with the name lib/gem-name.rb so in this case I needed lib/ceilingfish-toto.rb.

This doesn't seem to be true for some other gems to operate correctly. For example mime-types or rest-client but they do not show up with gem which, but they do actually work.

I'm not sure this is entirely correct yet, I'm sure there should be a way to get a gem with a hyphen in the name to behave correctly. If I find out I'll post back and let y'all know.

Answer 3

It's not the hyphen.

gem which searches for library files in gems, not gems. Compare:

$ gem which haml
/home/dave/.gem/ruby/1.8/gems/haml-3.0.12/lib/haml.rb
$ ls haml-3.0.12/lib/h*
haml  haml.rb  haml.rbc

Peachy. Note the existance of lib/haml.rb.

$ gem which rails
ERROR:  Can't find ruby library file or shared library rails
$ ls rails-2.3.8/lib/r*
rails_generator.rb  railties_path.rb  rubyprof_ext.rb  ruby_version_check.rb

There is no lib/rails.rb. But try:

$ gem which railties_path # not a gem
/home/dave/.gem/ruby/1.8/gems/rails-2.3.8/lib/railties_path.rb

So gem which ceilingfish-toto throws an error even when ceilingfish-toto is installed because there is no lib/ceilingfish-toto.rb file (there's not even a lib folder).