Define_method with predefined keyword arguments
I want to define a method that takes keyword arguments. I'd like this to be promoted when no keyword arguments were provided and I can do it myself, but ideally I'd like to let Ruby do it for me. Also I would like to be able to test the method I just defined using Method#parameters
. If I use the abbreviated double sign (for example **kwargs
), the actual structure I expect is not visible parameters
.
I can of course do this:
define_method(:foo) do | foo:, bar: |
# ...
end
which achieves the desired result:
method(:foo).parameters
# => [[:keyreq, :foo], [:keyreq, :bar]]
but I cannot pass these arguments programmatically, they have to be literally put into the code. Is there a way to get around this?
source to share
You should use eval
to define arguments dynamically (not just keyword arguments) eg. using class_eval
:
class MyClass
name = :foo
args = [:bar, :baz]
class_eval <<-METHOD, __FILE__, __LINE__ + 1
def #{name}(#{args.map { |a| "#{a}:" }.join(', ')}) # def foo(bar:, baz:)
[#{args.join(', ')}] # [bar, baz]
end # end
METHOD
end
MyClass.new.foo(bar: 1, baz: 2)
#=> [1, 2]
MyClass.instance_method(:foo).parameters
#=> [[:keyreq, :bar], [:keyreq, :baz]]
source to share