ParametersExtra
Purpose
You've got a method, but want to know more about the arguments? #arity
and #parameters
(if available) are useful,
but not nearly enough. You need something better. Like, the default arguments. ParametersExtra makes this simple. It operates
on a source file to supply the more details argument information by parsing the code itself.
Usage
Pretend you have a file your_ruby_file.rb
:
class MyClass
def initialize
@default_value = 'hello'
end
def something(one, two = 'two', three = @default_value, *more, &block)
end
end
To look at the arguments to something and you're in Ruby 1.9 (please see https://twitter.com/igrigorik/status/19461463110320128), just require it normally:
require 'your_ruby_file'
MyClass.instance_method(:something).args
Otherwise, do the following:
ParametersExtra.load('your_ruby_file') # <-- this also requires the file
MyClass.instance_method(:something).args
This will return an ArgList
object. You can then look at the names & types.
MyClass.instance_method(:something).args.names
# => [:one, :two, :three, :more, :block]
MyClass.instance_method(:something).args.types
# => [:required, :optional, :optional, :splat, :block]
If you want to get the value of a default argument, you'll need a context in which to evaluate it, namely, an instance of the class from which the method derives.
obj = MyClass.new
obj.method(:something).args.last.default_value
# => 'hello'