From: Charles Oliver Nutter <headius@...>
Date: 2010-04-06T09:42:30+09:00
Subject: [ruby-core:29270] Proposal: Module#thunk_method

Many people use define_method solely so they can define a new method
that just returns a value, such as for memoization. Unfortunately
define_method is a full block dispatch, and as a result it can be a
lot slower than regular method calls.

I propose a new method Module#thunk_method which defines a
fast-as-possible method that just returns the value you give it:

class Foo
  thunk_method :value, "some value"
end

Foo.new.value # => "some value"

This would eliminate define_method cases like this:

# lazy-memozing value method
def value
  a = some_expensive_calculation
  self.class.class_eval {define_method(:value) {a}}
end

Thoughts? Should this go into RedMine?

- Charlie