Is there anything more idiomatic than the following?
foo.class == String
This question is related to
ruby
idioms
typechecking
I think you are looking for instance_of?. is_a? and kind_of? will return true for instances from derived classes.
class X < String
end
foo = X.new
foo.is_a? String # true
foo.kind_of? String # true
foo.instance_of? String # false
foo.instance_of? X # true
I think a better way is to create some predicate methods. This will also save your "Single Point of Control".
class Object
def is_string?
false
end
end
class String
def is_string?
true
end
end
print "test".is_string? #=> true
print 1.is_string? #=> false
The more duck typing way ;)
You can do:
foo.instance_of?(String)
And the more general:
foo.kind_of?(String)
foo.instance_of? String
or
foo.kind_of? String
if you you only care if it is derrived from String somewhere up its inheritance chain
A more duck-typing approach would be to say
foo.respond_to?(:to_str)
to_str indicates that an object's class may not be an actual descendant of the String, but the object itself is very much string-like (stringy?).
In addition to the other answers, Class defines the method === to test whether an object is an instance of that class.
Source: Stackoverflow.com