# Navigating through the official Ruby documentation **URL:** \ **Category:** ruby-talk\ **Created:** [10 November 2011 17:22 UTC](https://rubytalk.org/t/navigating-through-the-official-ruby-documentation/64105 "2011-11-10T17:22:36Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![Fily\_Salas](https://avatars.discourse-cdn.com/v4/letter/f/977dab/32.png) [@Fily\_Salas](https://rubytalk.org/u/Fily_Salas)\ **Post date:** [10 November 2011 17:22 UTC](https://rubytalk.org/t/navigating-through-the-official-ruby-documentation/64105/1 "2011-11-10T17:22:36Z")
Hi, I have been trying to learn Ruby and so far so good I'm slowly leering the basics. I was trying to start referring to the Docs but I'm a little confused, I was expecting to see a list of all Ruby classes and underneath the class name a list of all of its methods but it has more than just methods, I don’t know if I still need more knowledge about the language in order for me to understand the information provided in the official Ruby Docs. Class Name > > methods Class Name > > methods I see some methods start with a "#" some with "::" and than you have the following sections: In Files, Class/Module Index, Parent etc. I’m guessing this has to do with Modules vs Classes. Can someone be so kind and go through the Ruby Docs and basically explain how is this organized? As I said I don't know if it’s because I don't fully understand the Ruby syntax or I simply need some adviceon how to use this documentation. Thanks a lot > **···** > > -- > Posted via [http://www.ruby-forum.com/\](http://www.ruby-forum.com/%5C). ---
**Author:** ![Sam\_Rose1](https://avatars.discourse-cdn.com/v4/letter/s/bbce88/32.png) [@Sam\_Rose1](https://rubytalk.org/u/Sam_Rose1)\ **Post date:** [10 November 2011 17:37 UTC](https://rubytalk.org/t/navigating-through-the-official-ruby-documentation/64105/2 "2011-11-10T17:37:56Z")
Okay, let's see... > **[Class: Array (Ruby 1.9.3)](https://ruby-doc.org/core-1.9.3/Array.html)** > > Class : Array - Ruby 1.9.3 Let's take the Array docs as an example. By the way you're talking, I'm going to take a shot in the dark and guess you're used to the Java API documentation? 🙂 So you are familiar with the idea of static and non-static methods (if not, just read on and see if it makes sense. Otherwise ask). In Ruby, static methods are described as "class methods". These are methods that are not called from an instance of a class, but the class itself. For example:     Class.method\_name(args) Is how you would see a class method called. In the Ruby documentation, these are prefixed with two colons :: Non-static methods are referred to as "instance methods", and these are called like so:    c = Class.new    c.some\_method(args) They're called in the instance of a class and in the Ruby documentation these are prefixed with a hash (or pound if you're American) # The parent of a class is what the current class inherited from. In Ruby, there's a hierarchy similarish to Java's. Everything inherits from the Object class: [Class: Object (Ruby 1.9.3)](http://ruby-doc.org/core-1.9.3/Object.html) (Object inherits from BasicObject for some reason, I would need to ask someone else why this is, though, sorry :)). If you don't understand object orientation, just say so and I'll find you some good resources. Modules are a really cool thing in Ruby. The "Included Modules" section of a Ruby doc page tells you what modules the class is "mixing in". I wrote an article about Ruby mixins, you can find it here: [http://samwho.co.uk/blog/2011/09/12/ruby-mixins/\](http://samwho.co.uk/blog/2011/09/12/ruby-mixins/%5C). It gives an overview of what you can do with Ruby modules and likens them to similar concepts in other languages that you might be more familiar with. If you find that it confuses you, let me know where so I can reword it. The "Class/Module Index" section of the page just looks like a list of all classes in Ruby's standard library so you can quickly navigate through them. I hope this helps demystify the Ruby docs. Feel free to ask about anything you're unsure of 🙂 > **···** > > On 10 November 2011 17:22, Fily Salas \ wrote: > > > Hi, > > > > I have been trying to learn Ruby and so far so good I'm slowly leering > > the basics. I was trying to start referring to the Docs but I'm a little > > confused, I was expecting to see a list of all Ruby classes and > > underneath the class name a list of all of its methods but it has more > > than just methods, I don’t know if I still need more knowledge about the > > language in order for me to understand the information provided in the > > official Ruby Docs. > > > > Class Name > > > > > > methods > > > > Class Name > > > > > > methods > > > > I see some methods start with a "#" some with "::" and than you have the > > following sections: In Files, Class/Module Index, Parent etc. I’m > > guessing this has to do with Modules vs Classes. > > > > Can someone be so kind and go through the Ruby Docs and basically > > explain how is this organized? > > > > As I said I don't know if it’s because I don't fully understand the Ruby > > syntax or I simply need some adviceon how to use this documentation. > > > > Thanks a lot > > > > -- > > Posted via [http://www.ruby-forum.com/\](http://www.ruby-forum.com/%5C). ---
**Author:** ![Marvin\_GA\_lker](https://avatars.discourse-cdn.com/v4/letter/m/e95f7d/32.png) [@Marvin\_GA\_lker](https://rubytalk.org/u/Marvin_GA_lker)\ **Post date:** [10 November 2011 17:48 UTC](https://rubytalk.org/t/navigating-through-the-official-ruby-documentation/64105/3 "2011-11-10T17:48:06Z")
> Hi, Hi, > I have been trying to learn Ruby and so far so good I'm slowly > leering the basics. I was trying to start referring to the Docs but > I'm a little confused, I was expecting to see a list of all Ruby > classes and underneath the class name a list of all of its methods > but it has more than just methods, I don’t know if I still need > more knowledge about the language in order for me to understand the > information provided in the official Ruby Docs. Assuming you’re refering to [Index of Files, Classes & Methods in Ruby 1.9.3 (Ruby 1.9.3)](http://ruby-doc.org/core-1.9.3/), it’s relatively easy. On the left side you have the "In Files" section. This tells you the names of the files inside the Ruby sourcecode where methods of your respective class are defined. For instance, for the Array class at [Class: Array (Ruby 1.9.3)](http://ruby-doc.org/core-1.9.3/Array.html) there are "array.c" and "pack.c" listed. This means, methods of this class are defined inside these files. Normally this shouldn't bother you, it's just an additional information (this can be useful in combination with gems if you don't know which files to require). On the right side you see the actual class/module documentation. > I see some methods start with a "#" some with "::" Those starting with # are instance methods, those starting with :: are class methods, i.e. methods you can call directly on the class. Array::new therefore is the same as Array.new (although the first form is AFAIK discouraged in actual code). The # is no valid Ruby syntax (if you try this, you’re likely to get syntax errors as this introduces a comment). > and than you have the following sections: In Files, See above. > Class/Module Index This is the list of all documented classes and modules, not just those related to e.g. Array. > Parent This is the parent class of the class you’re currently looking at. Look up what inheritance means if this isn’t clear to you. > I’m guessing this has to do with Modules vs Classes. No. Classes in Ruby are basically modules with the specific ability to create instances of themselves (via the ::new method). Sometimes, e.g. in the Array class, there’s also a section called "included modules". This lists all the modules that have been added to a class by using the Module#include method. Search for "mixins" if you want to know more on this. Both "Included modules" and "Parent" can list entities containing more methods than those of the class you’re looking at. For example, arrays have a method #max, but you won’t find this in the documentation of the Array class. It comes from the Enumerable module. Vale, Marvin > **···** > > Am 10.11.2011 18:22, schrieb Fily Salas: ---
**Author:** ![Fily\_Salas](https://avatars.discourse-cdn.com/v4/letter/f/977dab/32.png) [@Fily\_Salas](https://rubytalk.org/u/Fily_Salas)\ **Post date:** [10 November 2011 18:50 UTC](https://rubytalk.org/t/navigating-through-the-official-ruby-documentation/64105/4 "2011-11-10T18:50:59Z")
Double WOW! for you two guys. I'm always impress about the help I get here. Very good information, it basically answers all of my questions. One thing I see here is that I don't fully understand the big difference between Classes and Modules in Ruby but you even read my mind and added a link. > [http://samwho.co.uk/blog/2011/09/12/ruby-mixins/](http://samwho.co.uk/blog/2011/09/12/ruby-mixins/) I was thinking that Modules were just a form of separating classes (Name Scopes for classes). The only language I know a little bit is Actionscript 3.0 and it uses Packages to enclose classes but apparently in Ruby Modules do this and more. Thanks a lot Sam Rose > **···** > > -------------------------------- > > > @Marvin Gülker > > No. Classes in Ruby are basically modules with the specific ability to > > create instances of themselves (via the ::new method). > > As I mentioned above I need to have a better understanding about modules > and classes. > > > For example, arrays have a method #max, but you won’t find > > this in the documentation of the Array class. It comes from the Enumerable > > module. > The problem I see with this (if you want to call it a problem) is that > for novice like me, there is no way to know what methods have been > inherited from the module or other classes since they are not listed > here, I could open the module or the class itself, but how do you know > what methods have been inherited to other classes. > > I asked for one thing and I always end up learning other things, > awesome. YOU GUYS ARE AWESOME! > > I LOVE THIS FORUM > > -- > Posted via [http://www.ruby-forum.com/\](http://www.ruby-forum.com/%5C). ---
**Author:** ![botp1](https://avatars.discourse-cdn.com/v4/letter/b/6de8d8/32.png) [@botp1](https://rubytalk.org/u/botp1)\ **Post date:** [11 November 2011 01:32 UTC](https://rubytalk.org/t/navigating-through-the-official-ruby-documentation/64105/5 "2011-11-11T01:32:56Z")
irb(main):040:0\> system "ri Array | head" = Array \< Object > **···** > > On Fri, Nov 11, 2011 at 2:50 AM, Fily Salas \ wrote: > > > The problem I see with this (if you want to call it a problem) is that > > for novice like me, there is no way to know what methods have been > > inherited from the module or other classes since they are not listed > > here, I could open the module or the class itself, but how do you know > > what methods have been inherited to other classes. > > ------------------------------------------------------------------------------ > = Includes: > Enumerable (from ruby core) > > (from ruby core) > ------------------------------------------------------------------------------ > Arrays are ordered, integer-indexed collections of any object. Array indexing > starts at 0, as in C or Java. A negative index is assumed to be relative to > =\> true > > irb(main):041:0\> Array.methods.grep /methods/ > =\> [:instance\_methods, :public\_instance\_methods, > :protected\_instance\_methods, :private\_instance\_methods, :methods, > :singleton\_methods, :protected\_methods, :private\_methods, > :public\_methods] > > irb(main):052:0\> system "ri instance\_methods | head" > = .instance\_methods > > (from ruby core) > === Implementation from Module > ------------------------------------------------------------------------------ >   mod.instance\_methods(include\_super=true) -\> array > > ------------------------------------------------------------------------------ > > =\> true > > irb(main):054:0\> Array.instance\_methods > =\> [:inspect, :to\_s, :to\_a, :to\_ary, :frozen?, :==, :eql?, :hash, :, > :=, :at, :fetch, :first, :last, :concat, :\<\<, :push, :pop, :shift, > :unshift, :insert, :each, :each\_index, :reverse\_each, :length, :size, > :empty?, :find\_index, :index, :rindex, :join, :reverse, :reverse!, > :rotate, :rotate!, :sort, :sort!, :sort\_by........ \ > > irb(main):061:0\> (Array.instance\_methods - Array.instance\_methods(false) ).sort > =\> [:!, :!=, :!~, :===, :=~, :\_\_id\_\_, :\_\_send\_\_, :all?, :any?, :chunk, > :class, :clone, :collect\_concat, :define\_singleton\_method, :detect, > :display, :dup, :each\_cons, :each\_entry, :each\_slice, > :each\_with\_index, :each\_with\_object, :entries, :enum\_for, :equal?, > :extend, :find, :find\_all, :flat\_map, :freeze, :grep, :group\_by, > :initialize\_clone, :initialize\_dup, :inject, :instance\_eval, > :instance\_exec, :instance\_of?, :instance\_variable\_defined?, > :instance\_variable\_get, :instance\_variable\_set, :instance\_variables, > :is\_a?, :kind\_of?, :max, :max\_by, :member?, .......\ ---
**Author:** ![jake\_kaiden](https://avatars.discourse-cdn.com/v4/letter/j/a698b9/32.png) [@jake\_kaiden](https://rubytalk.org/u/jake_kaiden)\ **Post date:** [12 November 2011 15:19 UTC](https://rubytalk.org/t/navigating-through-the-official-ruby-documentation/64105/6 "2011-11-12T15:19:44Z")
hi Fily,   you can think of a module as a collection of useful methods that you can pass around (mix in) between various classes. from what i understand modules have a lot less 'overhead' than classes as well.   you could write a module called 'Transmission' in which you define how to shift gears - and then mix that module into different vehicle classes that will all share the methods defined in the module...   module Transmission     attr\_reader :gear     def num\_of\_gears=(n)       ...     end     def clutch       ...     end     def shift(up\_or\_down)       ...     end     def grind\_gears       ...     end   end   class Car     include Transmission     def initialize(n)       num\_of\_gears = (n)       ...     end     ...   end   class Motorcycle     include Transmission     def initialize(n)       num\_of\_gears = (n)       ...     end     ...   end   bike = Motorcycle.new(5)   car = Car.new(4)   bike.clutch   bike.shift('up')   car.clutch   car.shift('up')   etc....   - j > **···** > > -- > Posted via [http://www.ruby-forum.com/](http://www.ruby-forum.com/). ---
**Author:** ![Luca\_Email](https://avatars.discourse-cdn.com/v4/letter/l/76d3ee/32.png) [@Luca\_Email](https://rubytalk.org/u/Luca_Email)\ **Post date:** [29 December 2011 06:56 UTC](https://rubytalk.org/t/navigating-through-the-official-ruby-documentation/64105/7 "2011-12-29T06:56:06Z")
-----Messaggio originale----- > **···** > > Da: jake kaiden [[mailto:jakekaiden@yahoo.com](mailto:jakekaiden@yahoo.com)] > Inviato: sabato 12 novembre 2011 16:20 > A: ruby-talk ML > Oggetto: Re: Navigating through the official Ruby documentation > > hi Fily, > >   you can think of a module as a collection of useful methods that you can > pass around (mix in) between various classes. from what i understand > modules have a lot less 'overhead' than classes as well. > >   you could write a module called 'Transmission' in which you define how to > shift gears - and then mix that module into different vehicle classes that > will all share the methods defined in the module... > >   module Transmission >     attr\_reader :gear >     def num\_of\_gears=(n) >       ... >     end >     def clutch >       ... >     end >     def shift(up\_or\_down) >       ... >     end >     def grind\_gears >       ... >     end >   end > >   class Car >     include Transmission >     def initialize(n) >       num\_of\_gears = (n) >       ... >     end >     ... >   end > >   class Motorcycle >     include Transmission >     def initialize(n) >       num\_of\_gears = (n) >       ... >     end >     ... >   end > >   bike = Motorcycle.new(5) >   car = Car.new(4) > >   bike.clutch >   bike.shift('up') > >   car.clutch >   car.shift('up') > >   etc.... > >   - j > > -- > Posted via [http://www.ruby-forum.com/](http://www.ruby-forum.com/). > > -- > Caselle da 1GB, trasmetti allegati fino a 3GB e in piu' IMAP, POP3 e SMTP autenticato? GRATIS solo con [Email.it](http://Email.it) [http://www.email.it/f](http://www.email.it/f) > > Sponsor: > Capodanno a Riccione, Pacchetto Relax: Mezza Pensione + bagno turco + solarium + massaggio. Wifi e parcheggio gratis. 2 giorni euro 199 a persona > Clicca qui: [http://adv.email.it/cgi-bin/foclick.cgi?mid=11978&d=29-12](http://adv.email.it/cgi-bin/foclick.cgi?mid=11978&d=29-12)