How does Rubygem require all gems? [duplicate]

Question

This question already has an answer here:

• How can I debug require in Ruby 1.9 1 answer

I got interested in Rubygem, and started to explore how does it works, and found out that after 1.9, Rubygem's require became THE require.

With the code below:

require 'debugger'
debugger
require 'thor'

I started to n and l and s, but got stuck at:

  # specification.rb:263
  def self._all # :nodoc:
    unless defined?(@@all) && @@all then
      specs = {}

      self.dirs.each { |dir|
        Dir[File.join(dir, "*.gemspec")].each { |path|
          spec = Gem::Specification.load path.untaint
          # #load returns nil if the spec is bad, so we just ignore
          # it at this stage
          specs[spec.full_name] ||= spec if spec
        }
      }

      @@all = specs.values

      _resort!
    end
    @@all
  end

It seems that before stepping into the method above, @@all has already be been prepared. Then I set break-points everywhere @@all =, but none of the break-points are reached.

What am i missing???

---

EDIT:

Look at my question again. See require 'debugger'? I feel like a fool.

Now the question is "How can I debug require"?

---

CLOSED:

Plz see this great answer:https://stackoverflow.com/a/16069229/342366

Answer 1

Thx again for this greet answer:https://stackoverflow.com/a/16069229/342366, i did a little debugging myself.

For some one google to this question(and lazy to debug), i decide to post the answer to "How does Rubygem require all gems?"

There are the key-steps below:

1. load all ".gemspec" in "Ruby193\lib\ruby\gems\1.9.1\specifications"

   Dir[File.join(dir, "*.gemspec")].each { |path|
     spec = Gem::Specification.load path.untaint
     # #load returns nil if the spec is bad, so we just ignore
     # it at this stage
     specs[spec.full_name] ||= spec if spec
   }
   

2. sort the gems by version desc

   @@all.sort! { |a, b|
     names = a.name <=> b.name
     next names if names.nonzero?
     b.version <=> a.version
   }
   

3. got the first gem (the higher version)

   self.find { |spec|
     spec.contains_requirable_file? path
   }
   

4. activate the gem and all dependencies~ Everyone's happy.