Get class location from class object

Question

I have a bunch of code to look at, and now it is debugging time. Since I have never been a fan of Ruby's debugger I am looking for a way of going through code and reading it.

What I am trying to do is get the location of the file where a loaded class is defined:

Foo::Bar.create(:param) # how can I know file location in runtime?

For smaller, better organized, projects, I would just search for class Bar but here that is not possible since there are many classes named Bar, and, to make matters worse, some of them are under the same namespace. I know, it's trouble waiting to happen.

Note: I'm using Ruby 1.8.7.

Answer 1

For Methods and Procs Ruby 1.9 has method called source_location:

Returns the Ruby source filename and line number containing this method or nil if this method was not defined in Ruby (i.e. native)

So you can request for the method:

m = Foo::Bar.method(:create)

And then ask for the source_location of that method:

m.source_location

This will return an array with filename and line number. E.g for ActiveRecord::Base#validates this returns:

ActiveRecord::Base.method(:validates).source_location
# => ["/Users/laas/.rvm/gems/ruby-1.9.2-p0@arveaurik/gems/activemodel-3.2.2/lib/active_model/validations/validates.rb", 81]

For classes and modules, Ruby does not offer built in support, but there is an excellent Gist out there that builds upon source_location to return file for a given method or first file for a class if no method was specified:

• ruby where_is module

EDIT: For Ruby 1.8.7 there is a gem that backports source_location:

• ruby18_source_location

Answer 2

FYI, In Rails's console or debugging sessions of Rails apps, you can find out the disk-location of the file where that particular class is defined. like

> show-source Job

this will give you

From: /home/john/projects/iisifix/app/models/job.rb @ line 13:
Class name: Job
Number of monkeypatches: 6. Use the `-a` option to display all available monkeypatches
Number of lines: 66

class Job < ApplicationRecord
  belongs_to :quote_request
  belongs_to :garage