How do I require a specific version of a ruby gem?

Question

Specifically, the ruby-oci8 gem. I have both 1.0.7 and 2.0.4 installed. I want 1.0.7.

I can just require oci8, but I don't get the version I want.

irb(main):001:0> require 'oci8' => true irb(main):002:0> OCI8::VERSION => "2.0.4" 

I can require using the full path to the file, which works, but is not going to be portable:

irb(main):001:0> require 'C:\Ruby\lib\ruby\gems\1.8\gems\ruby-oci8-1.0.7-x86-mswin32-60\lib\oci8' => true irb(main):002:0> OCI8::VERSION => "1.0.7" 

I can use the gem command to ask for the version I want, but it doesn't appear to actually load the library:

irb(main):001:0> gem 'ruby-oci8', :lib=>'oci8', :version=>'=1.0.7' => true irb(main):002:0> OCI8::VERSION NameError: uninitialized constant OCI8     from (irb):2 

I would definitely favor this last approach if would load the library, rather than just confirming that it's present on my system. What am I missing?

Answer 1

My problem was twofold:

1) confusing gem command syntax with that used in config.gem lines in a rails environment.rb configuration file.

2) failing to issue a require command after the gem command.

Proper usage in a script is:

gem 'ruby-oci8', '=1.0.7' require 'oci8'           # example is confusing; file required (oci8.rb) is not                           # same name as gem, as is frequently the case 

Proper usage in a rails 2.3.x environment.rb file is:

config.gem "ruby-oci8", :version=>'1.0.7' 

Thanks to the folks at http://www.ruby-forum.com/topic/109100