The ri_for gem allows "runtime documentation lookup", it shows 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.
Examples
>> 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;
end
>> A.new.ri_for :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.
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 run the methods and step into them. Deftly convenient.
Installation
$ 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
>> A.new.my_methods
=> {:first, :second, :third]}
Object#methods2
Like #methods, but inserts a marker after my_methods are shown:
>> A.new.methods2
=> ["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
ori: 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.
method_source: Similar, I think it's embedded in pry as well.
Feedback
Comments/suggestions welcome rogerdpack on gmail or @rdp on github