多个instance_of？

Question

我如何让Object#instance_of?接受多个参数，以便类似下面的例子？

class Foo; end
class Bar; end
class Baz; end

my_foo = Foo.new
my_bar = Bar.new
my_baz = Baz.new

my_foo.instance_of?(Foo, Bar) # => true
my_bar.instance_of?(Foo, Bar) # => true
my_baz.instance_of?(Foo, Bar) # => false

Answer 1

[Foo,Bar].any? {|klass| my_foo.instance_of? klass}

Answer 2

如果你需要这样做一次，肯的回答是可行的。

[Foo,Bar].any? {|klass| my_foo.instance_of? klass}

如果你这样做几次，可能会有其他事情发生，即Foo和Bar之间的共性可以更明确：

module Foobarish; end
class Foo
  include Foobarish
end
class Bar
  include Foobarish
end
class Baz; end

Foo.new.kind_of? Foobarish # => true
Bar.new.kind_of? Foobarish # => true
Baz.new.kind_of? Foobarish # => false

Answer 3

您还可以使用alias_method_chain现有的instance_of?实现来扩展它所需的功能：

>> Object.class_eval do
>?   def instance_of_with_multiple_arguments(*arguments)
>>     arguments.any? { |klass| instance_of_without_multiple_arguments(klass) }
>>   end
>>
>>   alias_method :instance_of_without_multiple_arguments, :instance_of?
>>   alias_method :instance_of?, :instance_of_with_multiple_arguments
>> end