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  1. eval DATA.read
  2.  
  3. class Foo
  4.   extend Ova
  5.  
  6.   def bar a, b = String, c = [Numeric], d = :to_h | Hash | :keys, e
  7.     'This is just silly.'
  8.   end
  9.  
  10.   def bar a = String
  11.     bar a.to_i
  12.   end
  13.  
  14.   def bar a = Numeric
  15.     a * 2
  16.   end
  17.  
  18.   def bar a = [Numeric]
  19.     a.map(&:to_s)
  20.   end
  21. end
  22.  
  23. class Bar
  24.   def keys
  25.   end
  26. end
  27.  
  28. foo = Foo.new
  29. p foo.bar 21
  30. p foo.bar '21'
  31. p foo.bar [1, 2, 3]
  32. p foo.bar -> {}, '?!', [1, 2, 3], Bar.new, ObjectSpace
  33. p foo.bar :x, 'y'
  34.  
  35. __END__
  36. module Ova
  37.   # autovivifying map from [class][method][signature] to Method
  38.   @@Ova = Hash.new { |h, k| h[k] = Hash.new(&h.default_proc) }
  39.  
  40.   # Wrap #respond_to? for parity with Class#===.
  41.   Responder = Struct.new(:method) do
  42.     def === obj
  43.       obj.respond_to?(method)
  44.     end
  45.   end
  46.  
  47.   Sum = Struct.new(:types) do
  48.     def === obj
  49.       types.any? { |t| t === obj }
  50.     end
  51.   end
  52.  
  53.   def self.signature imeth
  54.     iseq  = RubyVM::InstructionSequence.of(imeth).to_a
  55.     insns = iseq.last
  56.     info  = iseq.grep(Hash).reduce(:merge)
  57.  
  58.     [Object] * info[:lead_num].to_i +
  59.  
  60.     info[:opt].to_a.each_cons(2).map do |a, b|
  61.       from, to = insns.index(a), insns.index(b)
  62.       insns[from...to].grep(Array).reduce([]) do |stack, (op, arg)|
  63.         stack << case op
  64.         when :getconstant # classes
  65.           const_get(arg)
  66.         when :putobject # symbols
  67.           Responder.new(arg)
  68.         when :newarray
  69.           [stack.pop]
  70.         when :duparray # single-symbol arrays (?)
  71.           [Responder.new(arg[0])]
  72.         when :opt_send_without_block # alternation (|)
  73.           Sum.new(stack.pop(2))
  74.         else # "no-op"
  75.           stack.pop
  76.         end
  77.       end.pop
  78.     end +
  79.  
  80.     [Object] * info[:post_num].to_i
  81.   end
  82.  
  83.   def self.dispatch mname
  84.     proc do |*args, &blk|
  85.       matched, imeth = @@Ova[self.class][mname].find do |sig, _|
  86.         sig.size == args.size && sig.zip(args).all? do |match, obj|
  87.           obj.all? { |o| match[0] === o } rescue match === obj
  88.         end
  89.       end
  90.  
  91.       if matched
  92.         imeth.bind(self).call(*args, &blk)
  93.       else
  94.         raise ArgumentError,
  95.           "#{self.class}##{mname} of " +
  96.           "(#{args.map(&:class) * ', '})" +
  97.           " not implemented",
  98.             caller
  99.       end
  100.     end
  101.   end
  102.  
  103.   def method_added mname
  104.     return if caller[1]['method_added']
  105.  
  106.     imeth = instance_method(mname)
  107.     @@Ova[self][mname][Ova.signature(imeth)] = imeth
  108.  
  109.     return if @@Ova[self][mname].size == 1
  110.  
  111.     define_method(mname, Ova.dispatch(mname))
  112.   end
  113. end
Runtime error #stdin #stdout #stderr 0.01s 6528KB
comments (?)
stdin 
Standard input is empty
stdout 
42
42
["1", "2", "3"]
"This is just silly."
stderr 
prog.rb:33:in `<main>': Foo#bar of (Symbol, String) not implemented (ArgumentError)
https://ideone.com/G6M1tl
language:
Ruby (ruby 2.5.5)
created:
5 years ago
visibility:
public

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