Seven Languages in Seven Days: Ruby

Seven Languages in Seven Days: Ruby
prepared by @zachleat

Creator
Yukihiro Matsumoto
“Matz”

Influences
Lisp, Smalltalk, Perl

Trade-offs
Simplicity for Safety
Productivity for Performance

irb
Ruby’s Interactive Console

WHEN U DECLARE VARS

U DECLARE WEAKNESS
Courage Wolf

RUBY CODE ROI

ALWAYS RETURN
SOMETHING Business Cat

Y U NO EVALUTE STRING?

SINGLE QUOTES!!
puts “hello, #{language}”
Y U NO?

>> puts ‘literal string’
literal string

>> subject = ‘world’
=> “world”

>> puts “hello, #{subject}”
hello, world

Y U NO?

HUMANS ARE CARBON

RUBY IS OBJECTS
Philosoraptor

>> 4.class
=> FixNum

>> 4.methods
=> [“inspect”, “%”, “<<“, ...

>> false.class
=> FalseClass

Philosoraptor

MY CONDITIONALS

ALWAYS SUCCESSFUL
Success Kid

>> x = 4
=> 4

>> puts ‘True!!’ if x == 4
True!!
=> nil

>> puts ‘True!!’ unless x == 4
=> nil

>> puts ‘True!!’ if not true
=> nil

>> puts ‘True!!’ if !true
=> nil
Success Kid

# Everything but nil and false
# evaluate to true. 0 is true!
>> puts “This is true” if 0
This is true
=> nil

# and, &&
# or, ||

# &, | are the non-short circuit
# equivalents

Success Kid

THE BEST LOOPS

ITERATE OVER THIRST
The Most Interesting Man in the World

>> x = x + 1 while x < 10
=> nil
>> x
=> 10

>> x = x - 1 until x == 1
=> nil
>> x
=> 1

The Most Interesting Man in the World

KEYBOARD CAT
HAS NOTHING ON

DUCK TYPINGTechnologically Impaired Duck

>> 4 + ‘four’
TypeError: String can’t be coerced
into Fixnum

# Strongly typed
# Dynamic: Checked at run time

>> a = [‘100’, 100.0]
=> [‘100’, 100.0]
>> while i < 2
>> puts a[i].to_i
>> i += 1
>> end
100
100
Technologically Impaired Duck

FFFFFUUUUUUUUUU

UUUUUUUNCTIONS
FFFUUUUUU

>> def tell_the_truth
>> true
>> end

# Last expression is return value

Technologically Impaired Duck

>> animals = [‘lions’, ‘tigers’]
=> [‘lions’, ‘tigers’]

>> numbers = {1 => ‘one’, 2 =>
‘two’}
=> {1=>”one”, 2=>”two”}

# Symbols
>> ‘string’.object_id
=> 3092010
>> ‘string’.object_id
=> 3089690
>> :string.object_id
=> 69618
>> :string.object_id
=> 69618

>> def winning(options = {})
>> if(options[:profession] == :gambler)
>> true
>> else
>> false
>> end
>> end
=> nil

>> winning
=> false

# {} optional for last parameter
>> winning(:profession => :lawyer)
=> true

YO DAWG I HEARD YOU
LIKED CODE BLOCKS

SO YOU COULD RUN CODE
IN YOUR CODE

>> 3.times { puts ‘hi’ }
hi
hi
hi

>> animals = [‘lions’, ‘tigers’]
>> animals.each {|a| puts a}
lions
tigers

# Blocks can be passed as
parameters
>> def pass_block(&block)
>> end
>> pass_block { puts ‘hi’ }

Classes
class MyClass
def initialize(name)
@name = name # instance var
@@other = ‘’ # class var
end

def name
return @name
end

# methods that check end in ?
end

my_class = MyClass.new(‘Name’)
my_class.name # returns ‘Name’

Modules
module MyModule
def name
return @name
end
end

class MyClass
include MyModule

def initialize(name)
@name = name
end
end

my_class = MyClass.new(‘Name’)
my_class.name # returns ‘Name’

Enumerable
# Implements each method

Comparable
# Implements <=> (spaceship) method

Open Classes
# First invocation defines
# Second invocation modifies

class NilClass
def blank?
true
end
end

class String
def blank?
self.size == 0
end
end

[‘’, ‘person’, nil].each {|a| puts a unless a.blank?}
# outputs person

Seven Languages in Seven Days: Ruby

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