The ri_for gem allows “runtime documentation lookup”, it show a method's source code/comments, ri (if available), arity, parameters, etc. all at runtime (for example within an irb session).

Don't know what a method does? Look it up! It has proven quite useful, and I wouldn't do a ruby-debug session without it–you might like it.


>> File.ri_for :delete

sig: File.delete arity -1 appears to be a c method Searching ri for sig: File.delete arity -1 … ———————————————————– File::delete

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

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

(end ri)

> “sig: File.delete arity -1”

(or alternatively use >> File.method(:delete).ri_for)

or, given this dynamically generated class, it can still show runtime parameter information:

>> class A;

 def go(a); end; 

>> :go

sig: A#go arity 1 def go(a)

# do nothing

end Parameters: go(a) Searching ri for sig: A#go arity 1 … Nothing known about A (end ri)

> “Parameters: go(a)”

Or (my favorite) use it within debug session:

74       assert(true == false)

(rdb:1) ri_for :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.


  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?)
  assert_block(build_message(message, "<?> is not true.", boolean)) { boolean }

end Parameters: assert(boolean, message = nil)

Thus, you can look at methods' source/rdocs without having to run the methods and step into them. Deftly convenient.


$ gem install ri_for

Usage: >> require 'ri_for' >> ClassName.ri_for :method_name # class or instance method name

>> some_instance.ri_for :method_name

Other goodies included:

Object#my_methods (stolen from a website somewhere)

An example: >> class A; def go; end; end >>

> :second, :third]

Object#methods2 (like #methods, but inserts a marker after my_methods are shown)


> [“go”, :“inherited methods after this point >>”, “to_yaml_style”, “inspect”, “methods_old”, “clone”, “public_methods”, “display”, “instance_variable_defined?”, “equal?”, “freeze”, “to_yaml_properties”, “methods”…]

Attributions ===

This gem wraps for convenience the functionality of Method#source_location, ruby2ruby, et al, and was inspired by a snippet from manvenu, SourceRef (MBARI), and Python's Method#desc. It also wouldn't be useful without irb and the ruby-debug folks. Thanks!

Related === (just lists ri, not method bodies and parameters, like mine does). also irb has a “help” command for obtaining (just lists ri) but it's pretty obscure nobody knows about it. >> help “Array” >> help “Array#[]” (just displays ri)

There are quite a few “#methods” helper utilties out there, too.

irbtools also lists a lot of other irb helpers.

Feedback ===

Comments/suggestions welcome rogerdpack on gmail or rdp on github