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# File 'lib/safety_check.rb', line 7
def safety_check(method_name, *arg_types)
if self.methods.include?(method_name)
receiver = self.singleton_class
elsif self.instance_methods.include?(method_name)
receiver = self
else
raise NoMethodError, "undefined method '#{method_name}' for #{receiver.inspect}"
end
unsafe_method_name = "#{method_name.to_s}_without_type_safety".to_sym
required_arity = receiver.instance_method(method_name).parameters.select { |type, name| type == :req }.length
if arg_types.length < required_arity
raise ArgumentError, "wrong number of arguments for #{method_name.inspect} (#{arg_types.length} for #{required_arity})"
end
receiver.send(:alias_method, unsafe_method_name, method_name)
receiver.send(:define_method, method_name) do |*args, &block|
if args.length < required_arity
raise ArgumentError, "wrong number of arguments (#{args.length} for #{arg_types.length}) when calling #{method_name.inspect}"
end
args.zip(arg_types).each do |arg, arg_type|
unless arg.is_a? arg_type
raise ArgumentError, "expected #{arg.inspect} to be a #{arg_type} when calling #{method_name.inspect}"
end
end
self.send(unsafe_method_name, *args, &block)
end
end
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