Exploring Ruby and Python interactively

Both Ruby and Python offer great interactive shells, also known as REPLs (Read Eval Print Loops). These are handy for verifying snippets of code. You can invoke Python’s by simply running python or Ruby’s by running irb, jirb (for jRuby), or rails c (for Rails).

Sometimes, however, one can be mystified as to what one can do with an object or module. Lately, I’ve been finding the Ruby API documentation especially frustrating.

Fortunately, both Python and Ruby let you see what’s available. In Python, you can call the dir() function, while Ruby has the handy .methods() method.


>>> dir("some string")
['__add__', '__class__', '__contains__', '__delattr__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__getitem__', '__getnewargs__', '__getslice__', '__gt__', '__hash__', '__init__', '__le__', '__len__', '__lt__', '__mod__', '__mul__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__rmod__', '__rmul__', '__setattr__','__sizeof__', '__str__', '__subclasshook__', '_formatter_field_name_split', '_formatter_parser', 'capitalize', 'center', 'count', 'decode', 'encode', 'endswith', 'expandtabs', 'find', 'format', 'index', 'isalnum', 'isalpha', 'isdigit', 'islower', 'isspace', 'istitle', 'isupper', 'join', 'ljust', 'lower', 'lstrip', 'partition', 'replace', 'rfind', 'rindex', 'rjust', 'rpartition', 'rsplit', 'rstrip', 'split', 'splitlines', 'startswith', 'strip', 'swapcase', 'title', 'translate', 'upper', 'zfill']

And Ruby:

irb(main):003:0> "some string".methods
=> [:to_java_bytes, :upcase!, :ascii_only?, :lstrip, :upto, :lines, :encoding, :prepend, :scan, :==, :clear, :squeeze!,:chop, :next!, :casecmp, :start_with?, :split, :to_f, :center, :reverse, :sub, :byteslice, :>, :upcase, :next, :strip!,:count, :sub!, :hash, :bytesize, :lstrip!, :to_sym, :<=, :replace, :length, :swapcase, :gsub, :intern, :succ, :capitalize, :each_codepoint, :oct, :delete!, :+, :initialize_copy, :to_java_string, :match, :unpack, :index, :rstrip!, :*, :each_char, :gsub!, :to_s, :empty?, :size, :swapcase!, :ljust, :downcase, :rpartition, :to_str, :getbyte, :sum, :crypt, :partition, :reverse!, :=~, :force_encoding, :each_byte, :tr!, :inspect, :to_c, :rstrip, :succ!, :<, :[]=, :valid_encoding?, :slice!, :slice, :insert, :tr_s!, :unseeded_hash, :squeeze, :dump, :===, :end_with?, :hex, :strip, :capitalize!, :bytes, :setbyte, :chop!, :each_line, :[], :encode, :include?, :chomp!, :<<, :encode!, :chomp, :rindex, :to_i, :<=>, :eql?, :tr_s, :chars, :codepoints, :delete, :chr, :to_r, :rjust, :%, :>=, :concat, :ord, :tr, :downcase!, :between?, :handle_different_imports, :include_class, :java_kind_of?, :java_signature, :methods, :define_singleton_method, :initialize_clone, :freeze, :extend, :nil?, :tainted?, :method, :is_a?, :instance_variable_defined?, :instance_variable_get, :singleton_class, :instance_variable_set, :public_method, :display, :send, :private_methods, :enum_for, :com, :to_java, :public_send, :instance_of?, :taint, :class, :java_annotation, :instance_variables, :!~, :org, :untrust, :protected_methods, :trust, :java_implements, :tap, :frozen?, :initialize_dup, :java, :respond_to?, :java_package, :untaint, :respond_to_missing?, :clone, :java_name, :to_enum, :singleton_methods, :untrusted?, :dup, :kind_of?, :javafx, :java_require, :javax, :public_methods, :instance_exec, :__send__, :instance_eval, :equal?, :object_id, :__id__, :!, :!=]


Published by

Leons Petrazickis

I'm a full-stack developer at IBM Digital Business Group. I do Ruby, Node, Python, Hadoop, Spark, as well as web scale devops with Docker and Terraform. My opinions are my own.