Ruby equivalent of Python's “dir”?

Question

In Python we can "dir" a module, like this:

>>> import re
>>> dir(re)

And it lists all functions in the module. Is there a similar way to do this in Ruby?

Answer 1

You can take a module, such as Enumerable, and send the methods method which lists all the methods the module defines. Classes that include this module will respond to these methods.

>> Enumerable.methods
=> ["inspect", "private_class_method", "const_missing", "clone", "method", "public_methods", "public_instance_methods", "instance_variable_defined?", "method_defined?", "equal?", "freeze", "included_modules", "const_get", "yaml_as", "methods", "respond_to?", "module_eval", "class_variables", "dup", "protected_instance_methods", "instance_variables", "public_method_defined?", "__id__", "object_id", "taguri", "yaml_tag_read_class", "eql?", "const_set", "id", "to_yaml", "taguri=", "singleton_methods", "send", "class_eval", "taint", "frozen?", "instance_variable_get", "include?", "private_instance_methods", "__send__", "instance_of?", "private_method_defined?", "to_a", "name", "to_yaml_style", "autoload", "type", "yaml_tag_class_name", "<", "protected_methods", "instance_eval", "<=>", "==", ">", "display", "===", "instance_method", "instance_variable_set", "to_yaml_properties", "kind_of?", "extend", "protected_method_defined?", "const_defined?", ">=", "ancestors", "to_s", "<=", "public_class_method", "hash", "class", "instance_methods", "tainted?", "=~", "private_methods", "class_variable_defined?", "nil?", "untaint", "constants", "autoload?", "is_a?"]

Answer 2

Maybe not answering the original question (depends on the use case), but for those who are looking for this to be used in the irb only, you can use "double-TAB" for autocompletion. Which, effectively, can also list (almost all) the methods available for a given object.

Put the following line into your ~/.irbrc file:

require 'irb/completion'

Now, (re)start the irb, start typing a method and hit TAB twice - irb autocompletes the input!

I actually learned it here: http://drnicwilliams.com/2006/10/12/my-irbrc-for-consoleirb/

Answer 3

If I stricly read your question, I must answer it that way: a file as specified by require in Ruby is just a container and does not have necessarely have any relation with a class. The content can be:

• a class
• a module
• plain code

or any combination of the above, several times. So you can not directly ask for all methods in a given file.

If you meant to list all methods of a given module or class, then the other answers are what you seek (mainly using the #methods method on a module name or class).