find-method performance

[epitron]

I looked into why find-method is so excruciatingly slow (it takes a minute or so on my machine). The major problem is that it's using Pry::Method.all_from_class on every single class, which does a lot of unnecessary, expensive operations.

Here's a much faster implementation:

# find classes that contain this method:
classes = ObjectSpace.each_object(Module).select { |c| c.method_defined? :some_method_to_find }
# (runtime: 0.01752s)

# find all instances of these classes:
instances = classes.map {|c| [c, ObjectSpace.each_object(c)] }
# (also really fast)

Finding class methods is the same, but with singleton_class.method_defined?:

# find classes with matching class methods
ObjectSpace.each_object(Module).select { |c| c.singleton_class.method_defined? :some_method_to_find }
# (stupidly fast)