How do you list the currently available objects in the current scope in ruby?

Question

I'm new to ruby and I'm playing around with the IRB.

I found that I can list methods of an object using the ".methods" method, and that self.methods sort of give me what I want (similar to Python's dir(builtins)?), but how can I find the methods of a library/module I've loaded via include and require?

irb(main):036:0* self.methods => ["irb_pop_binding", "inspect", "taguri", "irb_chws", "clone", "irb_pushws", "public_methods", "taguri=", "irb_pwws", "public", "display", "irb_require", "irb_exit", "instance_variable_defined?", "irb_cb", "equal?", "freeze", "irb_context ", "irb_pop_workspace", "irb_cwb", "irb_jobs", "irb_bindings", "methods", "irb_current_working_workspace", "respond_to?" , "irb_popb", "irb_cws", "fg", "pushws", "conf", "dup", "cwws", "instance_variables", "source", "cb", "kill", "help", "_ _id__", "method", "eql?", "irb_pwb", "id", "bindings", "send", "singleton_methods", "popb", "irb_kill", "chws", "taint",  "irb_push_binding", "instance_variable_get", "frozen?", "irb_source", "pwws", "private", "instance_of?", "__send__", "i rb_workspaces", "to_a", "irb_quit", "to_yaml_style", "irb_popws", "irb_change_workspace", "jobs", "type", "install_alias _method", "irb_push_workspace", "require_gem", "object_id", "instance_eval", "protected_methods", "irb_print_working_wor kspace", "irb_load", "require", "==", "cws", "===", "irb_pushb", "instance_variable_set", "irb_current_working_binding",  "extend", "kind_of?", "context", "gem", "to_yaml_properties", "quit", "popws", "irb", "to_s", "to_yaml", "irb_fg", "cla ss", "hash", "private_methods", "=~", "tainted?", "include", "irb_cwws", "irb_change_binding", "irb_help", "untaint", "n il?", "pushb", "exit", "irb_print_working_binding", "is_a?", "workspaces"] irb(main):037:0> 

I'm used to python, where I use the dir() function to accomplish the same thing:

>>> dir() ['__builtins__', '__doc__', '__name__', '__package__'] >>> 

Answer 1

I'm not entirely sure of what you mean by the 'current objects'. You can iterate over ObjectSpace, as has been mentioned already. But here are a few other methods.

local_variables instance_variables global_variables  class_variables constants 

There's one gotcha. They must be called at the right scopes. So right in IRB, or in an object instance or at class scope (so everywhere, basically) you can call the first 3.

local_variables #=> ["_"] foo = "bar" local_variables #=> ["_", "foo"] # Note: the _ variable in IRB contains the last value evaluated _ #=> "bar"  instance_variables  #=> [] @inst_var = 42 instance_variables  #=> ["@inst_var"]  global_variables    #=> ["$-d", "$\"", "$$", "$<", "$_", ...] $"                  #=> ["e2mmap.rb", "irb/init.rb", "irb/workspace.rb", ...] 

But umm, what if you want your program to actually evaluate them without needing you to type them manyally? The trick is eval.

eval "@inst_var" #=> 42 global_variables.each do |v|   puts eval(v) end 

The last 2 of the 5 mentioned at the beginning must be evaluated at the module level (a class is a descendant of a module, so that works).

Object.class_variables #=> [] Object.constants #=> ["IO", "Duration", "UNIXserver", "Binding", ...]  class MyClass   A_CONST = 'pshh'   class InnerClass   end   def initialize     @@meh = "class_var"   end end  MyClass.constants           #=> ["A_CONST", "InnerClass"] MyClass.class_variables     #=> [] mc = MyClass.new MyClass.class_variables     #=> ["@@meh"] MyClass.class_eval "@@meh"  #=> "class_var" 

Here's are a few more tricks to explore in different directions

"".class            #=> String "".class.ancestors  #=> [String, Enumerable, Comparable, ...] String.ancestors    #=> [String, Enumerable, Comparable, ...]  def trace   return caller end trace #=> ["(irb):67:in `irb_binding'", "/System/Library/Frameworks/Ruby...", ...]