not real ViewFromTo

module ViewFromTo

KLASSES = []

RULES = []

def self.extended(klass)

KLASSES << klass

RULES.each do |a, o, b, l|

if klass.to_s == a || a == '*'

m = klass.instance_method(o) if o != :method_missing and klass.method_defined?(o) # should exist better way

klass.define_method(o) do |*args, &blk|

m.bind(self).call(*args, &blk) if m

l.call(self, *args, &blk) if args[o == :method_missing ? 1 : 0].kind_of?(b) # should exist better way

end

end

end

end

def def_from pattern='*', meth=:method_missing, &blk

RULES << [pattern, meth, self, blk]

end

def def_to pattern='*', meth=:method_missing, &blk

klass = pattern == '*' ? Object : KLASSES.find { |k| k.to_s == pattern }

define_method meth do |*args|

self.instance_exec(*args, &blk) if args[meth == :method_missing ? 1 : 0].kind_of?(klass) # should exist better way

end

end

end

# the better way:

# 1. add full type check, see https://glot.io/snippets/f48os6pmhy

# 2. better wrap method_missing, this one is a fake one

class Apple

extend ViewFromTo

def_from '*' do # *.*(apple)

puts "i'm just an apple"

end

def_from 'Human', :taste do |human| # human.taste(apple)

puts "i'm taste #{human.age < 1 ? 'juicy' : 'odd'}"

end

end

class Human

extend ViewFromTo

attr_accessor :age

def initialize(age) @age = age end

def_to 'Apple', :taste do |apple| # human.taste(apple) # override previous one

puts age < 1 ? 'juicy' : 'cannot eat'

end

end

class OtherThing

extend ViewFromTo

end

Human.new(0).taste(Apple.new) # juicy

Human.new(2).taste(Apple.new) # cannot eat

OtherThing.new.taste(Apple.new) # i'm just an apple