Ruby Programming Introduction

by Anthony W. Brown

The Ruby Programming Language^

A partial introduction to the

Tuesday, March 26, 13

Introduction

This presentation is an adaptation from “The Ruby Programming Language” by Matz and the University of Washington’s Ruby and Rails PCE course.

This deck was originally intended to cover all object-oriented principles, popular tools and the Rails framework. If anyone likes this deck, I will create rest for you...


Useful Links

• http://www.ruby-doc.org/• http://apidock.com/ruby• http://apidock.com/rspec• http://zenspider.com/Languages/Ruby/

quickref.html


http://www.ruby-doc.org/

http://www.ruby-doc.org/

http://apidock.com/

http://apidock.com/

http://apidock.com/

http://apidock.com/

http://zenspider.com/Languages/Ruby/




Origins“Ruby is simple in appearance, but is very complex inside, just like our human body”

-Matz


Ruby is...

• Object Oriented• Dynamic• Reflective• Interpreted


Ruby in a Slide

• TDD• IRB• Gems• Bundler• Rspec


Tools

• git, github• RVM• Ruby Gems• RSpec• Rake • Guard


Install Check

# Check git version# Check Ruby version, 1.9.3?# Interactive Ruby Environment# Install the RSpec test tools

awb - bash - 80x24Last login: Sun Feb 10 11:28:48macpro:~ awb$ git --versionmacpro:~ awb$ ruby -vmacpro:~ awb$ irbmacpro:~ awb$ gem install rspec


git

# set or view configuration# copy repository# make current dir a repo# get current state or repo# add items to index# remove items from index# commit index to repo# move commits to remoter server# list of commits in this repo

Last login: Sun Feb 10 11:28:48

macpro:~ awb$ git log

awb - bash - 80x24

macpro:~ awb$ git configmacpro:~ awb$ git clonemacpro:~ awb$ git initmacpro:~ awb$ git status

macpro:~ awb$ git rm

macpro:~ awb$ git push

macpro:~ awb$ git add

macpro:~ awb$ git commit

Last login: Sun Feb 10 11:28:48


RSpechttp://rubydoc.info/gems/rspec-expectations/2.4.0/RSpec/Matchers

describecontextitshouldeqbe_akind_of

#describes “what” in a test#describes “when” in a test#performs an operation,“does”#Class attribute#matcher#matcher#matcher

awb - bash - 80x24

macpro:~ awb$ rspec -c -f d ‘filename’Last login: Sun Feb 10 11:28:48


http://rspec.rubyforge.org/rspec/1.1.9/classes/Spec/Matchers.html

http://rspec.rubyforge.org/rspec/1.1.9/classes/Spec/Matchers.html

Rake

=beginRuby version of make; A DSL to define tasksEasy to manage dependencies and tasks=end

task :clean_update dosystem(clean_up_script.sh)MyClass.update_everything(‘./path’)

end

Rake is Ruby’s version of make: a domain specific language to define tasks. Easy to manage dependencies and tasks.

awb - bash - 80x24

macpro:~ awb$ rake clean_updateLast login: Sun Feb 10 11:28:48


ObjectsEverything in Ruby is an object.

“hello”

4

[]

my_array

:symbol

#string

#integer

#empty array

#comment

=beginmulti-line comment=end


Operators

-!*~

#Unary operators

+ -* / **<< && ||

#Binary operators

my_variable?‘True’:

#Ternary operators


Assignment

a = b

a += 1

# lvalue are assignment,rvalue # are reference

Hold values, or references to objects.

#lvalue = rvalue

#abbreviated assignment same #as a = a + 1

a, b = 1, 2

a, b, c = [1,2]

# a = 1, b = 2

# a = 1, b = 2, c = nil


Expressions

‘hello’

File

true

false

nil

self

=begin

Expressions evaluate to and return a value.

Compound expressions leverage an operator (+/-/*/%)

=end


VariablesVariables hold values, or references to objects

a = “Woof!”

b = a

b.object_id

c = a.dup

b[0] = “P”

#initialize to prevent NameError

#Local: my_var#Global: $password#Class: @@counter#Instance: @name#Constant: MY_CONST

#b = “Woof!”

#b = “Woof!”

#c = “Woof!”

#a and b = “Poof!” c still #“Woof!”


StringsText is represented by strings, which are of class String.

’35’

“35”

#single-quoted string literal

#double-quoted string literal

my_age = “35”

“ My age is #{my_age}”

#Assigned string variable

#Interpolation


NumbersRuby has 5 built-in classes for numbers in the standard library.

123456789

3.141519

1,000,000,000,000

#Literal Objects

#Class Hierarchy:

#Numeric

#Integer

#Fixnum

#Bignum


ArraysArrays are lists of values that can be accessed by their position.

my_array = [“1”, “2”, “3”

1, 2, 3

a, << “1”, “2”, “3”

my_array = []

[]

Array.new

=begin

Arrays are not typed, ordered, mutable, literal, and Enumerable.They contain many operators and methods like:

+ << *

.push .pop

.sort.

.uniq!

=end


HashesHashes are key/value pairs.

my_hash = {:a =>“1”, :b =>“2”}

my_hash = {}

{a: 1, b: “2”}

my_hash = [:a] = 1

my_hash = [:b] = 2

Hash.new

=begin

Hashes like arrays are not typed. They are ordered,and Enumerable.They contain many operators and methods like:

=end


IteratorsLike a loop, iterators perform operations on data sets.

3.times {puts “thank you!”}

my_data.each { |x| print x}

[1,2,3].map { |x| x*5}

#

#

#


MethodsMethods pass messages to objects. They have 5 parts; the object, message, parameter, block and body.

my_method

my_method parameter

my_method (parameter)

my_method (parameter1, 2)

object.my_method

#Various ways to call a method

#Syntax structure#object.method(parameter) {block}

my_method par1, par2, do|block| tweet! “#{par1} just did #{par2}”

end


Method ObjectObjects receive messages. Every object has methods and self

#dangerous methods end in ‘!’

# => true

def my_method; end

object.respond_to? :my_method


Method MessageThe Message is required. Style is to use snake_case naming conventions.

[].empty?

#predicate methods end in ‘?’

# => true

#dangerous methods end in ‘!’

doesn’t modify the method

does modify the method

my_method.uniq

my_method.uniq!


Method MessageThe Message is required. Style is to use snake_case naming conventions.

[].empty?#predicate methods end in ‘?’# => true

#dangerous methods end in ‘!’#doesn’t modify the method#does modify the method

my_method.uniqmy_method.uniq!

def name = str@name = str

end

#index lookup (-ish) methods use []class MyObject def [] num@collection[num]

endend

#attribute setter method name end =


Method Parameters

def say str1, str2, str3“#{str1} --- #{str2}”

end

say ‘hi’, ‘bye’

#0 or more, comma separated, #defaults can be defined.

# => ‘hi --- bye’


BlocksNameless function (arbitrary code) passed to a method with {code} or ‘do code end’. Any method can receive a block.

def my_method par {|block_par| use block par}

end

=begin

Blocks to not have to be named as a parameter and are ignored if not explicitly used by a method. The block passed describes what to do with each thing.

=end

# => I’m a dog. Bark, bark!

#

def my_dogprint “I’m a dog...”yield

end

run {print “Bark, bark!”}


Blocks

# Calling Enumerablemodule Enumerable

def map result = [] self.each do |object| result << yield object end result end

end

[1, 2, 3].map { |n| n * 2 }

Example

# Create a method# Assign a variable# Create a block

# => [2,4,6]


More to come. If you have any questions, please contact me on various social media networks with the alias @awbrown.


Ruby Programming Introduction

Documents

end awb bash

git awb bash

end tasks

check awb bash

end blocks

end run

docode end

method parameters