Often when learning about an object, it can be useful to see the methods available to call on the object. I find this helpful when debugging, using a new gem, or simply looking to learn more about an object. Luckily, Ruby exposes Object#public_methods, Object#protected_methods and Object#private_methods, all of which return a list of symbols representing the names of methods defined on an object. For example, if we wanted to see the public methods defined on true, we could do: true.public_methods
=> [:===, :^, :inspect, :to_s, :&, :|,
:taint, :tainted?, :untaint, :untrust,
:untrusted?, :trust, :methods,
:singleton_methods, :protected_methods,
:private_methods, :public_methods...
... many many more! ...
..., :instance_exec, :__send__]
There are 61 many public methods, quite a lot! This isn't because there are many methods defined explicitly on TrueClass itself, but rather because of all the methods defined on ancestors of TrueClass. true.class.ancestors
=> [TrueClass, Object,
Kernel, BasicObject]
This brings us to the crux of this week's tip. Object#public_methods, Object#protected_methods and Object#private_methods all take an optional boolean parameter denoting whether to include methods defined on ancestors. This means if we pass in false to Object#public_methods, we should see only the methods in the receiver. true.public_methods(false)
=> [:===, :^, :inspect, :to_s, :&, :|]
This is a much more comprehensible list, and more helpful when looking to learn about the nuances of a specific object. |
