Method: Object#when

Defined in:
lib/ext/object.rb

#when(val = :noval) ⇒ Object Also known as: if?



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# File 'lib/ext/object.rb', line 136

def when(val=:noval)
  iam = self

  return val == self ? self : Forwarder.new do |name, *args, &block|
    iam.define_singleton_method(:else) { |*vars| self }
    iam
  end if val != :noval

  Forwarder.new do |name, *args, &block|
    if (iam.respond_to?(name) || iam.methods.include?(name)) && (got = iam.__send__(name, *args, &block))
      thn = Forwarder.new do |name, *inargs, &block|
        if name.sym == :then
          if block
            ret = iam.instance_exec(*inargs, &block)
            ret.define_singleton_method(:else) { |*vars| self }
            ret
          elsif inargs.mt?
            thn
          else
            ret = inargs.sequester!
            ret.define_singleton_method(:else) { |*vars| self }
            ret
          end
        else
          ret = __send__(name, *inargs, &block)
          ret.define_singleton_method(:else) { |*vars, &blk|
            if vars.mt? && block._?
              Forwarder.new { ret }
            else
              ret
            end
          }
          ret
        end
      end
    else
      ret = Forwarder.new do |name, *args, &block|
        if name.sym == :then
          els = Forwarder.new do |name, *targs, &block|
            if name.sym == :else
              if block
                iam.instance_exec(*targs, &block)
              elsif targs.mt?
                Forwarder.new { |name, *eargs, &block| __send__(name, *eargs, &block) }
              else
                targs.sequester!
              end
            else
              els
            end
          end
        else
          iam
        end
      end
    end
  end
end