Get all local variables or available methods from

问题:

When I go into irb and type in a command that does not exist I get an error stating

"undefined local variable or method 'my_method' for main:Object (NameError)"

Is there a way to just get a list of what local variables or methods ARE available? This would be really useful for exploring ruby.

回答1:

Look for methods in the Kernel, Object and Module : e.g. local_variables, instance_methods, instance_variables.

Other great methods in there. inspect is another one.

回答2:

Great answers.
As you explore, you have these at your disposal:

obj.private_methods 
obj.public_methods 
obj.protected_methods 
obj.singleton_methods

and

MyClass.private_instance_methods 
MyClass.protected_instance_methods 
MyClass.public_instance_methods

Usage like :

obj.public_methods.sort

Can make review easier too.

Some special cases exist like

String.instance_methods(false).sort

... will give you only the instance methods defined in the String class, omitting the classes it inherited from any ancestors. As I expect you know, you can see more here: http://www.ruby-doc.org/docs/ProgrammingRuby/ but it's not as fun as inspecting and reflecting in irb.

Happy exploring -

Perry

回答3:

To find out instance variables, you can use Kernel#instance_variables as Zabba pointed out.

For methods available on an object, I use my_object.methods - Object.methods to find out what non-obvious methods are available to my object. This narrows down the list and is considerably easy to read.