Multiple instance_of？

Question

我该如何让Object#instance_of?接受多个参数，以便像下面的例子那样工作？

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

如果你需要做的，有一次，肯的回答是要走的路。

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

如果你这样做了几次，虽然，有可能是别的事情上，即Foo和Bar之间的共性，可以更加明确：

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

您也可以alias_method_chain现有instance_of?落实它与你想要的功能扩展：

>> 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