A “run time RI for ruby methods”, this gem allows you to query for information about objects’ methods at runtime–for example within irb or ruby-debug. It reveals everything known about the method. This includes source, ri, arity, rdoc comments (1.9 only), etc.

For me it has proved quite useful, and I wouldn’t do a ruby-debug session without it–you might really like it.

Examples:

>> class A;

 def go(a); end; 
end

>> A.desc_method :go #<UnboundMethod: A#go> arity: 1 ri for A#go Nothing known about A (end ri) def go(a)

# do nothing

end Parameters: go(a)

>> File.desc_method :delete ri for File.delete ———————————————————– File::delete

File.delete(file_name, ...)  => integer
File.unlink(file_name, ...)  => integer

From Ruby 1.9.1

---

Deletes the named files, returning the number of names passed as
arguments. Raises an exception on any error. See also +Dir::rmdir+.

(end ri) #<Method: File.delete> arity: -1 appears to be a c method #parameters signature: delete( [[:rest]] )

Or (my favorite) a debug session:

(rdb:1) l= …

74       assert(assigns['order'].order_line_items.map(:unit_price).min >= -5)

… (rdb:1) desc_method :assert #<Method: StoreControllerTest(Test::Unit::Assertions)#assert> arity: -2 ri for Test::Unit::Assertions#assert —————————————— Test::Unit::Assertions#assert

assert(boolean, message=nil)

From gem test-unit-2.0.1

---

Asserts that +boolean+ is not false or nil.

Example:

  assert [1, 2].include?(5)

(end ri) def assert(boolean, message = nil)

_wrap_assertion do
  assert_block("assert should not be called with a block.") do
    (not block_given?)
  end
  assert_block(build_message(message, "<?> is not true.", boolean)) { boolean }
end

end Parameters: assert(boolean, message = nil)

Thus, you can look at methods’ source/rdocs without having to step into them. Deftly convenient.

How to Install=====

$ gem install rogerdpack-desc_method or $ gem install rogerdpack-desc_method –source gems.github.com if you don’t have gems.github.com as a gem source.

Usage: >> require ‘desc_method’ >> Class.desc_method :method_name # class or instance method name … >> some_instance.desc_method :method_name

Other goodies included:

Class#desc_class method

An example: >> Object.desc_class # outputs descriptive info about that class–RI, method list, etc. >> Object.desc_class :verbose => true # outputs RI, method lists including inherited methods, ancestors, all constants etc.

Kernel#methods has been monkey patched to output a “separator” between its inherited and non inherited methods–i.e. >> instance.methods

> [:first, :second, :after_this_are_inherited>>>>>, :some_inherited_method, :another_inherited_method] # adds in that separator

I’ll probably remove that in a future release since it turns out you can just run Kernel#methods(false) for about much.

Thanks ===

This gem wraps for convenience the functionality of Method#source_location, ruby2ruby, et al, and also contains some code inspiration from manvenu, SourceRef (MBARI), and Python’s Method#desc. It also wouldn’t be useful without irb and the ruby-debug folks. Thanks!

Comments/suggestions welcome rogerdpack on gmail or github