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Justin Mui

Justin Mui

Ruby Specifics

Slide Duration:

Table of Contents

I. Introduction to Ruby
Setting Up Your Environment

22m 8s

Intro
0:00
Installing Ruby
0:06
Ruby-lan.org
0:07
Three Ways of Installing Ruby
2:26
Compiling Ruby-Source Code
3:02
Third Party Tools
3:28
Other Implementations of Ruby
4:48
Windows Installation
5:21
RubyInstaller.org
5:22
Mac OSX and Linux Installation
6:13
Mac OSX and Linux Installation
6:14
Setting Up Debian/Linux
6:42
Setting Up Debian/Linux
6:43
Installing HomeBrew
6:56
HomeBrew for MAC OSX
6:57
HomeBrew Wiki
9:44
Installing HomeBrew
10:02
Setting Up Mac OSX
11:46
HomeBrew, RVM, OSX-GCC Installer, and Install Ruby 1.9.3
11:47
Ruby Version Manager (RVM)
12:11
Ruby Version Manager (RVM) Overview
12:12
Installing Ruby Version Manager (RVM): http://rvm.io
12:35
Install RVM with Ruby
14:20
Install RVM with Ruby
14:21
Install OSX-GCC-Installer
16:18
Download and Install Package for Your OSX
16:19
Install Ruby 1.9.3
17:28
Install Ruby 1.9.3
17:29
Test It Out!
18:09
rvm-help & ruby-v
18:10
Example: rvm gemset create educator
18:52
Set It As Default!
20:47
rvm Use 1.9.3@educator--default
20:48
Intro to Ruby

22m 20s

Intro
0:00
What is Ruby?
0:06
What is Ruby?
0:07
Ruby Standard Library
0:52
Who Created Ruby?
1:22
Yukihiro Matsumoto
1:23
History
2:45
The Name 'Ruby'
2:46
Ruby v0.95
3:10
Ruby v1.0
3:56
English Language Mailing List Rubytalk
4:08
ruby-forum.com & the Mailing Lists
4:27
Ruby In The West
9:51
Ruby on Rails
10:39
The Pragmatic Programmer's Guide to Ruby
11:30
rubyonrails.org
13:34
Current Ruby
14:42
Ruby 1.8.7, Ruby 1.9.3, and Ruby 2.0
14:43
Why Programmers Enjoy Ruby?
15:40
Why Programmers Enjoy Ruby?
15:41
Ruby Is An Interpreted Language
16:21
Ruby Is An Interpreted Language
16:22
What Is It Used For?
16:50
What Is It Used For?
16:51
Ruby is Object-Oriented
18:17
Example: 5.class
18:18
Example: 0.0.class
18:54
Example: true.class
19:03
Example: nil.class
19:12
Object Class
19:19
BasicObject
19:20
Example
19:52
Superclass
20:50
Fixnum → Integer → Numeric → Object
21:32
Basic Tools for Using Ruby

27m 44s

Intro
0:00
Interactive Ruby
0:08
irb: Interactive Command-Line Environment
0:09
Example
0:49
irb-v
0:50
irb-executes terminal
1:02
1.9.3-p125 > 'hi'
1:09
Live Demonstration
1:31
Why Use Interactive Ruby?
2:21
Why Use Interactive Ruby?
2:22
RDoc
3:05
RDoc
3:06
Ruby Core Documentation
3:32
Ruby Core Documentation: Example
5:30
Ruby Core Documentation: Markup
6:12
Ruby Core Documentation: Headings
7:44
Coding Example: RDoc
9:30
Why Use RDoc?
13:02
Learning Core Ruby Functions
13:03
Generating RDoc
15:31
rdoc-help # usage
15:32
Ruby Interpreter
15:57
ruby -- help
15:58
ruby [switches] [-] program [arguments]
16:16
Example: How to Run a Ruby Script
16:28
Rake
18:38
Rake Overview
18:39
Ruby Core Documentation: Rake
19:46
Coding Example: Rake
23:14
Why Was It Created?
24:30
Why Was It Created?
24:31
Lesson Summary
25:13
Lesson Summary
25:14
IDE/script Editors: MacVIM
26:24
Ruby Specifics

20m 45s

Intro
0:00
Ruby Specifics
0:06
Comments
0:51
Hashtags
1:00
Example
1:23
Multi-Line Comment
2:04
Example
3:10
RDoc Comments
4:02
When do you generate an Rdoc?
4:10
Headings and subheadings
4:24
Examples
4:48
Generating an Rdoc - example
4:50
Common Code Conventions
6:28
For every tab use two spaces indentation
7:38
Never use tabs
7:42
Common Code Conventions (Cont.)
8:18
Camel case
8:20
Snake case
9:18
Identifiers
9:44
Constants begin with CAP letter
10:00
Examples
10:10
Identifiers with Different Scoping
10:26
Global
10:34
Instance Variable
10:40
Class Variable
10:46
Examples
10:56
Reserved Keywords
12:22
Do not use reserved keywords in code
12:25
Parentheses are Sometimes Optional
13:04
Functions do not require parentheses
13:16
When in doubt, use parentheses
13:54
Examples
14:10
Newlines Are Statement Terminators
14:20
Examples
15:10
Continuation with a Period
16:20
Period means continue to next line
16:46
Multiple Statements Allowed on a Single Line
17:38
Try not to use semi-colons
17:58
Code Blocks
18:20
Use code blocks for one liners
18:28
Examples
18:40
Recommended for multiple lines
20:16
Ruby Data Types (Part 1)

29m 37s

Intro
0:00
Overview
0:10
Ruby Data Types
0:10
Numbers
0:16
Strings
0:18
Symbols
0:24
Numbers
0:30
Numeric
0:44
Float
0:50
Complex
0:56
BigDecimal
0:58
Rational
1:00
Integer (most popular) - Fixnum and Bignum
1:06
Fixnum stores 31 bits
1:18
Bignum stores larger bits
1:24
All number objects are instances of Numeric
1:28
Integer Literals
2:28
Represent whole-numbers
2:40
Examples - Different bases
2:42
Binary
3:04
Octal
3:30
Hexadecimal
3:44
Examples
4:06
Floating Point Literals
4:45
Examples
4:58
e-value can be capital or lowercase
5:30
Example
5:44
Strings
6:16
Mutable objects
6:18
Used for inserting and deleting text, searching, and replacing
6:26
String Rdoc
6:46
Definition
7:00
String Literals
8:20
Single-Quoted
8:28
Double-Quoted (most used)
8:50
Example
9:32
Escape Sequences
11:10
Newline
11:16
Tab
11:22
Double quote
11:28
Blackslash
11:36
Interpolation
11:50
Sprintf
13:48
Unicode Escaping
14:38
Example
15:50
Delimiters
16:18
Here Documents
17:18
Example
17:25
String Operators
19:58
Concatenation
20:03
Appending
20:40
String Equality
21:04
Example
21:24
Substrings
22:00
Range object (inclusive)
22:22
String Encoding
24:52
Differences between Ruby 1.8 and 1.9
24:56
Symbols
26:02
Definitions
26:04
Examples
26:46
When to use symbols
26:54
Symbols and Strings
27:42
Symbols Rdoc
28:22
Ruby Gems

25m 50s

Intro
0:00
RubyGems
0:08
What are RubyGems?
0:24
RubyGems.org
0:44
How RubyGems are used
2:06
Java's jar utility
2:50
Unix/Linux's tar utility
3:06
What is a Gem?
3:16
Definition of Gem
3:20
Version
3:34
Date
3:44
Author
3:50
Description
5:58
What Are the Uses?
4:18
Uses for Gems
4:22
Installation
5:06
How to install RubyGems
5:30
Updating to the Latest Ruby Gems
5:54
Testing
6:22
Example
6:34
Installing Rake
7:24
Example
7:46
Verifying
9:22
Example
9:56
Structure
10:56
gem.gemspec
11:30
Specification
13:40
What is in the gem?
13:42
Who made it?
13:50
Update gem version
13:58
Example
14:10
Create Our First Gem
17:20
Steps involved
17:28
RubyGems Guides
17:36
Example
20:02
Steps Review
18:56
Create Our First Gem (Cont.)
23:08
Building the gem
19:38
Example
20:00
Installing the gem
22:32
Run it
22:52
Publish it
23:04
Get Some Gems!
25:06
rake
25:14
rails
25:19
fastercsv
25:25
koala
25:37
Ruby Data Types (Part 2)

40m 24s

Intro
0:00
Ruby Data Types
0:15
Boolean
0:21
Arrays
0:27
Hashes
0:33
Range
0:37
Boolean Types
0:42
TrueClass
0:56
FalseClass
1:12
NilClass
1:18
TrueClass Examples
2:48
FalseClass Examples
3:22
Arrays
4:16
Ordered collection of objects
4:22
Can hold different objects
4:32
Starts at index 0
4:50
Array of Strings
5:50
Example
5:52
Arrays (Cont.)
6:20
Can be created using literals
6:22
Can be created using constructors
6:54
Position and indexed value
8:04
Negative Indexed Values
8:56
Shift and Unshift
10:18
Push and Pop
11:38
.delete method
12:38
Addition and Subtraction
13:32
Union and Intersection
14:48
Insert
15:52
Iteration
16:52
Arrays Rdoc
17:48
Hashes
22:08
Maps and Associative Arrays
22:44
Created using the constructor
22:56
Created using a hash literal
24:02
Stored in a hash table
25:26
Example
25:50
Accessing Key-Values
27:46
Deletion
29:48
Iteration
31:04
Hashes Rdoc
32:04
Ranges
36:40
Two dots are inclusive
36:57
Three dots are exclusive
37:16
Example
37:50
Ranges Rdoc
38:24
Objects

1h 5m 46s

Intro
0:00
Objects
0:10
Object References
1:36
Ruby Core
2:16
Example
4:30
Creating New Objects
6:00
New Method
6:08
Initialize Method
6:31
Example
7:18
Garbage Collection
9:54
Global values always reachable
10:25
Object Identity
11:08
Every object has an object identifier
11:20
Object identifier is constant and unique
11:30
Example
11:54
Object Class
12:58
Class method
13:10
Superclass method
13:28
Object Testing
14:46
is_a?
15:49
respond_to?
16:26
String and Regexp
18:10
Comparing two object instances
20:06
Example
23:30
Object Equality
25:48
Comparing objects
25:54
equal?
25:58
Popular way to test for equality
27:16
Opposite way to test for equality
27:25
Arrays
28:30
Hash
29:42
Case equality operator
30:47
Class tests
31:16
Range tests
31:48
Symbol tests
32:32
Object Conversion
33:14
Explicit conversion
33:54
Implicit conversion
35:00
Example
36:12
Object Conversion: Kernel Module
38:22
Array
38:38
Float
39:26
Integer
39:58
String
40:10
Example
40:34
Object Conversion: Coerce
42:00
Used for mixed type numeric operations
42:08
Example
43:40
Object Conversion: Boolean
47:42
Every object has a boolean value
47:44
Example
48:54
Object Copying
50:52
dup
50:58
clone
51:03
Example
51:42
Object Freezing
57:36
Object Marshaling
58:38
Save state
59:04
Load state
59:27
Example
59:32
Tainted Objects
1:01:50
taint
1:02:08
farm field
1:02:12
Untrusted Objects
1:04:06
trust
1:04:24
untrust
1:04:34
untrusted?
1:04:42
Loops

38m 54s

Intro
0:00
Loops
0:12
while and until
0:48
for and in
0:54
iterators
1:04
enumerable in objects
1:06
While-loop
1:14
Will keep going is condition is true
1:18
Until-loop
2:58
Will keep going until condition becomes true
3:06
Single Expression Loops
4:20
Compact form
4:30
Expressed as a modifier
4:42
Do-While Loop
5:52
Executes body first
6:06
Do-Until Loop
7:54
Similar to do-while loop
7:58
Using Break Inside Loops
8:54
break
8:58
For-In Loop
11:56
for-loop
12:06
var
12:34
collection
12:54
body
13:00
Examples
13:08
Examples (Cont.)
15:54
Nested loops
16:40
Numeric Iterators
18:32
upto
18:40
downto
18:42
times
18:48
Examples
20:28
External Iterators
21:00
Enumerator class
21:04
Rdoc
21:16
Enumerables in Objects
24:35
Enumerable is a mix-in
24:41
RDoc
25:24
Commonly Used Enumerables in Objects
27:01
Array
27:19
Hash
27:51
Range
28:47
Examples
29:29
Enumerables in Objects (Cont.)
31:13
File Processing
31:15
Example
31:45
Enumerables in Objects (Cont.)
33:07
collect
33:23
select
34:11
reject
34:59
inject
35:29
Strings

28m 30s

Intro
0:00
Strings
0:08
Why do you want to get familiar with strings?
1:00
String Creation
1:16
new
1:28
empty?
1:50
length or size
2:10
Example
3:12
String Manipulation
4:40
slice
4:56
square brackets [ ]
5:02
token
5:40
[fixnum]
6:52
offset and length
8:40
chaining
12:42
String Insertion
12:56
insert
12:58
positive or negative index
13:46
String Updates
15:24
[token]
15:36
Examples
16:40
chop or chop!
17:54
chomp!
18:56
gsub
20:28
String Deletion
21:38
delete
21:38
String Reversal
22:46
reverse
22:52
String Manipulation
23:16
split(pattern=$, limit)
23:22
pattern
24:10
limit
24:15
upcase or upcase!
25:28
downcase or downcase!
26:02
swapcase
26:24
Incrementing Strings
27:26
next or next!
27:32
Check Out the Other Lessons
28:00
Ruby Data Types Part 1
28:12
Regular Expressions
28:18
Regular Expressions

33m 27s

Intro
0:00
Regular Expressions
0:10
How to create a regular expression
0:48
What goes inside
1:36
Metacharacters
3:10
Bracket expressions
3:14
Quantifiers
3:18
Anchors
3:20
Metacharacters
3:30
word and non-word characters
4:04
digit and non-digit characters
4:44
hexdigit and non-hexdigit characters
4:56
whitespace and non-whitespace characters
5:08
Examples
5:24
POSIX Bracket Expressions
7:48
Non-POSIX Bracket Expressions
9:48
Bracket Expression Examples
10:58
Quantifiers
12:34
Examples
13:30
Character Properties
17:24
Similar to POSIX bracket classes
18:22
More Character Properties
18:48
Examples
19:32
Anchors
20:08
Examples
21:14
Regular Expression Matching: Regexp Object
22:40
match
22:51
Regular Expression Matching: String Object
24:14
match
24:26
Regular Expression Modifier Characters
25:14
pat
25:38
Example
26:42
Regular Expression Modifier Objects
27:14
Example
28:38
Regexp Rdoc
30:40
Arrays

14m 35s

Intro
0:00
Arrays
0:12
Creating an Array with a Block
0:50
Alternative Ways to Create an Array
3:52
Checking the Class
5:14
Iterate through the array
5:26
Call the class method
5:28
Array Shortcuts
6:38
at(index)
6:44
delete_at(index)
7:28
first(n)
8:28
last(n)
9:28
Removing Duplicates
9:58
uniq or uniq!
10:04
Sorting the Array
10:48
sort or sort!
10:54
Getting the Index
11:35
index
11:56
rindex
12:38
Multidimensional Arrays
12:56
flatten
13:33
Check Out the Earlier Lesson
14:16
Ruby Data Types Part 2
14:26
Hashes

27m 48s

Intro
0:00
Hashes
0:12
Creating Hashes
1:18
Setting a Default Value
2:24
Accessing Hashes
4:16
Accessible by keys or by values
4:28
Keys must be unique
4:36
Creating Hashes
5:16
Comma-separated list
5:42
Hash rocket
8:28
Examples
10:16
Iterating Keys and Values
11:43
each_key
12:04
each_value
14:04
Merging Hashes
16:10
merge(other_hash)
16:20
Sorting Hashes
18:46
Replacing Hashes
20:57
replace(other_hash)
21:18
Converting Hashes to Other Classes
22:04
to_a
22:22
to_s
23:22
Example
24:34
Check Out the Earlier Lesson
27:22
Ruby Data Types Part 2
27:32
Math Operations, Part 1

28m 47s

Intro
0:00
Math Objects
0:12
Numeric
0:26
Integer
0:38
Float
1:02
Fixnum
1:14
Bignum
1:56
Rational
2:04
Math
2:24
Math Operations
2:36
Example
3:14
div(numeric)
4:54
divmod(numeric)
6:30
modulo(numeric)
7:23
quo(numeric)
8:18
remainder(numeric)
9:35
Operation Precedence 1 of 3
10:35
Operation Precedence 2 of 3
13:18
Operation Precedence 3 of 3
14:28
Abbreviated Math Operations
14:54
Move the operator in front of the equal sign
15:52
Numbers
16:36
Numeric Class
17:06
Numeric Methods
18:41
ceil
18:52
floor
19:32
round
19:50
Example with Numbers
20:20
Numeric Methods (Cont.)
22:20
truncate
22:28
num.step(limit, step)
23:02
Numeric Rdoc
25:26
Math Operations, Part 2

28m 51s

Intro
0:00
Math Operations
0:12
Math Module
0:24
Rational Numbers
0:44
Complex Numbers
0:52
Prime Numbers
0:58
Matrices
1:06
Math Module
1:12
PI and E
1:32
Math Module Methods
2:47
atan2(x,y)
2:56
cos(x)
3:14
exp(x)
3:44
Examples
4:38
log(x)
5:44
log(num, base)
6:34
log10(x)
7:04
sin(x)
7:34
sqrt(x)
7:52
tan(x)
8:06
Math Functions: Part 1 of 3
8:12
Math Functions: Part 2 of 3
9:32
Math Functions: Part 3 of 3
10:19
Math Module Rdoc
11:25
Rational Numbers
13:23
How to use
14:06
Example
15:02
Mathematical Ruby Scripts (Mathn)
16:25
Example
17:28
Complex Numbers
18:26
polar
18:56
rect
19:10
Complex Number Examples
19:18
Prime Numbers
20:14
each(ubound=nil)
20:44
prime?
21:22
Example
21:58
Matrices
23:15
build(row_size, column_size=row_size)
23:44
Example
24:44
Matrix Rdoc
24:58
Dates and Times

26m 1s

Intro
0:00
Dates and Times
0:12
Time Class
0:38
Methods of the Time Class
1:43
now
1:44
at(time)
2:10
Epoch & Unix Timestamp Conversion Tools
3:19
Components of a Time
5:07
Convert Time to an Array
5:54
to_a
6:08
Creating a New Time
6:48
Time.local
7:08
Year is required
7:22
Time.utc
8:12
What should be specified
9:30
More Methods of the Time Class
10:16
strftime(string)
11:26
RDoc
12:50
Date Library
16:46
Initializing a New Date
17:08
Parsing Dates
18:28
parse(string)
18:42
Today's Date
19:19
Date.today
19:22
Tomorrow's Date
20:22
Next
20:28
Next week
21:22
Count Down
21:26
Count Up
22:37
Components of a Date
23:20
Converting to Datetime
23:48
to_datetime
24:00
Initializing a Datetime
24:24
Converting to Time
25:23
self.to_time
25:32
Methods: Part 1

31m 24s

Intro
0:00
What is a Method?
0:12
Basic Method
0:58
Return Value
4:37
return
4:46
Factorial Example
6:18
Example
8:46
Return Two Values
10:06
Set the return keyword
10:14
Collected and returned as an array
10:28
Undefining Methods
11:22
undef method_to_undefine
11:44
Example
12:32
Method Names
13:02
Begin with lowercase letter
13:16
Separate longer words with underscores
13:26
Can end with equal sign, question mark, or exclamation point
14:03
Equal sign
14:26
Method Names with Question Mark
14:44
empty?
15:24
Method Names with Exclamation Point
16:01
mutators
16:12
! means use with caution
16:46
Method Aliases
18:05
alias new_method existing_method
18:42
Operator Methods
20:00
Operators
20:02
Array Operators
20:10
Unary Operators
20:32
Binary Operators
20:40
Example
21:28
Methods and Parentheses
25:00
Optional in most cases
25:20
Required in other cases
27:13
Methods and Blocks
27:54
Associated with blocks
28:18
block_given?
28:26
yield
28:36
Example
29:24
Methods: Part 2

20m 11s

Intro
0:00
Methods with the Unary Ampersand Operator
0:14
&
0:34
Block to a Proc
0:56
Example
2:02
Proc object
3:58
Example
5:04
Methods with Default Values
5:54
Example
7:12
Methods with variable-Length Arguments
8:05
How to create it
8:36
Example
11:06
Using Hashes with Arguments
13:02
Multiple arguments
13:08
Solution
13:30
Example
14:56
Rdoc
18:12
Classes: Part I

26m 51s

Intro
0:00
Classes
0:10
Definition of a class
0:14
Class represents a container
0:32
Can be reused
0:46
Creating our First Class
1:00
Keyword class will create new class
1:06
Name must begin with capital letter
1:30
Instantiating Our First Class
2:46
New will create a new instance of class
2:58
Initializing Values
3:58
Definition of def
4:14
Instance method
5:08
Example
7:02
Defining the to_s Method
8:24
Creating a string representation class
8:34
Example
10:54
Self in the Class
12:16
Definition of self
12:26
Example
13:54
Accessor Methods
15:52
getter methods
16:22
Example
17:00
Setter Methods
18:00
Mutator methods
18:02
Example
19:46
Automating Getter and Setter Methods
21:10
Defined in the module class
21:30
attr_reader
21:54
attr_writer
22:48
attr creates getter and setter methods
23:50
Example
24:28
Notes on Ruby's Accessor Methods
25:32
Classes: Part II

26m 42s

Intro
0:00
Defining Operators
0:10
You can define arithmetic operators
0:32
Unary Operators
0:46
Let's define operators in our class!
0:56
Example
2:52
Class Methods
6:24
Examples
6:56
Opening Up the Class
9:38
Adds an additional method
9:54
Examples
11:04
Array and Hash Access Method
15:40
Use square brackets
16:02
Define your own has access method
16:08
Example
16:56
Enumerating The Values
18:40
Define the each iterator
18:40
Testing for Equality
19:36
Class Triplex
19:50
Examples
20:54
Constants
25:00
Usually defined at the top of class
25:24
Classes: Part III

53m 36s

Intro
0:00
Class Variables
0:14
Example
2:16
Ruby Glass Jar Example
8:50
Class Instance Variables
10:20
Instance variables of class objects
10:46
Advantage of class instance variables
11:18
Examples
11:30
Method Visibility
16:16
Three types of method visibility
16:26
Public methods
17:34
Private methods
17:38
Protected methods
18:04
Invoking Method Visibility
19:21
Public , Protected, and Private Visibility
19:22
Invoking Method Visibility With Arguments
21:39
Example: Invoking Method Visibility
22:12
Class Visibility
23:31
Instance and Class Variables are Private
23:32
Constants are Public
24:00
Makes Existing Class Methods Private
24:27
Makes Existing Class Methods Public
25:08
Example: Class Visibility and class GlassJar
25:43
Subclassing
27:08
Subclassing: Subclass and Superclass
27:09
Example: Subclassing
29:43
Inheritance
30:05
Inheritance
30:06
Example: Inheritance
31:25
Subclassing and Inheritance
31:34
Descendants
31:41
Ancestors
31:56
More On Descendants and Ancestors
32:08
Extending a Class
33:27
Extending a Class
33:28
Coding Example: Extending a Class
34:24
Overriding a Method
36:41
Overriding a Method
36:42
Coding Example: Overriding a Method
37:18
Modifying Methods with Chaining
38:52
Modifying Methods with Chaining
38:53
Super
39:25
Coding Example: Modifying Methods with Chaining
39:51
The Singleton Pattern
44:52
Introduction to The Singleton Pattern
44:53
Setting Up Singleton
45:28
The Instance Method
45:58
Rdoc for Singleton: Usage
46:23
Rdoc for Singleton: Implementation
47:45
Coding Example: Singleton
49:38
Modules

24m 19s

Intro
0:00
Modules
0:04
What is Modules?
0:05
Modules Examples
0:40
Modules: Mix-Ins
3:31
What is a Mix-in?
3:32
Modules: Namespace
4:07
What is a Namespace?
4:08
Why Use a Namespace?
5:13
Example of a Namespace Module
5:59
Example of Mixing in The Module Into the Global Scope
6:00
Modules: Creation
7:04
How to Create a New Module?
7:05
Modules: Usage
8:19
How to Use It?
8:20
class Poker & class Bridge
9:13
Creating Our Module as a Mix-In
9:41
Example of a Module Using Instance Methods
9:42
Coding Example
10:20
Creating Our Module as a Namespace
12:11
Implement Class Methods for the Module
12:12
Coding Example
14:56
Loading Our Module
19:46
Loading Our Module Overview
19:47
Require & Load
20:15
Coding Example: Loading Module
20:48
Lesson Summary
23:36
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Ruby Specifics

  • This lesson will go through ruby syntax and common code conventions that are often asked by a new Ruby developer.
  • Comments are creating using '#'
  • Camel Case should be reserved only for classes
  • Parentheses are optional for functions
  • Newlines are statement terminators
  • You can continue method calling using a period
  • Multiple statements are allowed on a single line if separated using a semi-colon ";"

Ruby Specifics

Lecture Slides are screen-captured images of important points in the lecture. Students can download and print out these lecture slide images to do practice problems as well as take notes while watching the lecture.

  • Intro 0:00
  • Ruby Specifics 0:06
  • Comments 0:51
    • Hashtags
    • Example
  • Multi-Line Comment 2:04
    • Example
  • RDoc Comments 4:02
    • When do you generate an Rdoc?
    • Headings and subheadings
    • Examples
    • Generating an Rdoc - example
  • Common Code Conventions 6:28
    • For every tab use two spaces indentation
    • Never use tabs
  • Common Code Conventions (Cont.) 8:18
    • Camel case
    • Snake case
  • Identifiers 9:44
    • Constants begin with CAP letter
    • Examples
    • Identifiers with Different Scoping
    • Global
    • Instance Variable
    • Class Variable
    • Examples
  • Reserved Keywords 12:22
    • Do not use reserved keywords in code
  • Parentheses are Sometimes Optional 13:04
    • Functions do not require parentheses
    • When in doubt, use parentheses
    • Examples
  • Newlines Are Statement Terminators 14:20
    • Examples
  • Continuation with a Period 16:20
    • Period means continue to next line
  • Multiple Statements Allowed on a Single Line 17:38
    • Try not to use semi-colons
  • Code Blocks 18:20
    • Use code blocks for one liners
    • Examples
    • Recommended for multiple lines

Transcription: Ruby Specifics

Welcome to educator.com.0000

This site is on Ruby specifics.0001

For this course, we want to go over a lot of the common things you will see in Ruby--a lot of things people see as questions, and a lot of specifics that are just on Ruby itself.0006

First, we are going to go over the Ruby syntax.0022

There are a lot of things about Ruby that are different versus other languages, that you should know.0026

Hopefully, we will cover them here; and the second thing we are going to go over is the common code conventions.0032

The reason is that there are a lot of conventions in Ruby that you wouldn't see in other languages.0038

They are a lot more different, and we will go over it now.0045

The first thing we want to go over is comments.0051

They are created using the hashtag.0055

If you use other languages, you might see a forward slash--that's in PHP.0058

It is similar in Javascript; but in Ruby, they are hashtags.0067

What happens is, wherever the comment starts, it is going to continue to the end of that line.0073

For example, here on this slide, you have x=100.0082

You have this hashtag here, and then you have the actual comment you leave here.0087

You will notice that anything afterwards, it will pick it up, all the way to the new line over there, and the same over here.0093

The actual Ruby code looks at x=100 and y=200, and then it will use that for its Ruby compilation and whatever process they're parsing.0104

And here, on this site, we are showing you a multiple-line comment. This is one of the most common ways you will be commenting when you are doing multiple lines.0117

I would recommend you use this one here.0131

You will notice, on this line, there are four hashtags.0137

This one is a two-liner, and you will notice that there is a space here, and a space here.0141

That is very common. If you leave a comment, you always need some kind of spacing here.0149

If you have more to this comment, you could just add another hashtag.0155

In this case, if it is a paragraph, I leave one hashtag, and another hashtag here.0160

And then, I put whatever code or code description I have.0167

Here is another multi-line comment.0183

This one is not as popular; you will see it more often in other languages.0189

It has docstring type comment.0194

It starts with this begin tag; that is when it tells Ruby, "OK, if you see this =begin, don't actually do anything with it--don't interpret it; instead, take this as a comment."0197

And you will notice that everything all the way from begin until it says end--that is all a comment.0210

So, the main thing here is =begin and =end.0226

That will create this type of comment; I wouldn't recommend it--it is good to know, though, if you are transitioning from one language to another.0231

For this example, I am going to show you an RDoc comment.0240

The reason we are going over this one is to show you, when you generate your RDoc, you can have headers that are larger and smaller, depending on the topic.0246

If it's a main heading versus a subheading, you will notice here that you have this one equals sign, which is the main heading.0258

For a subheading, you will notice that there are two equals signs.0268

And, you could continue that down--so it becomes a sub-subheading with equal equal.0272

You will notice that I actually have some RDoc comments here.0286

First, you will see, with "Overview," there is =Overview.0290

That is a heading, and then you will see =Usage--there is another heading.0296

Here is ==Options--there is a subheading.0302

And For Future Use--that is another subheading.0307

Let's go ahead and generate this out and see what it looks like.0310

Again, we are in the current directory.0321

There is the hello-world.rb--I'm just going to run rdoc there.0324

It is going to generate it into this Doc directory.0329

I'm going to open the index file.0334

And the one we are looking at is this myfirstclass.0342

So, you can see from this browser, Overview is part of the RDoc--you know that it is a very huge text piece.0346

Usage is our heading.0355

Options is our subheading, and For Future Use is our sub-subheading.0358

You will notice the size difference.0361

Let's minimize that...0367

The next one I want to go over, the second part, is common code conventions.0387

What we want to do here is to go over some of the most popular conventions that you need to know for Ruby, and a lot of things you will notice that are very questionable, that we hope to answer here.0392

Here is a very basic code piece.0406

The class is Book; we have an attribute assessor for title, author, description, content.0411

This is our constructor; initialize...it takes four arguments: title, author, description, content.0418

We create class lists and variables here.0425

We have a method called Summary; it creates a description, and that becomes a summary, because we get the first 150 characters.0428

And then, we have another method called Wordcount, and that counts the words from the content.0438

If you will get it all in...we will go into it in deeper parts in other lessons, too.0444

The first code convention is that you will use two spaces per indent.0451

And you will never use tabs.0458

That is very common. You will notice here that this is actually two spaces.0463

If you did have extra code, where it was a method and then you had an if statement; there would be another two spaces.0475

For every comment you have, you want to use two spaces indentation.0484

And also, you will notice at this class itself, the class is actually CamelCase.0496

But it is only for the class itself.0508

So we have the book--it's Capital--but then you will notice all the other methods here.0512

They are all snake_case, so they are all in this lowercase space format.0518

For an example of CamelCase, we could say, maybe, our next method could be BookTitle.0525

So, this would be an example of CamelCase.0539

But if I am making a method--let's say I make a method for BookTitle--you will never see capital letters; it will all be lowercase.0547

This is snake_case...let's call it that...0555

Let's call it get_title.0567

The next one we want to go over is identifiers.0582

You will use this all the time in coding.0585

They are very basic: you have your normal variables--your variable x, your variable temp--0588

You will also see constants.0596

Ruby convention for constants is that it always begins with a capital letter.0599

The recommended way is to keep it all caps, all the way.0604

So we have PI, all caps, MAX_WITH, all caps--between spaces, you use underscore.0610

And, in that same case, if you have different identifiers that are for different scopes...0624

Global has a dollar sign.0629

Instance variables have the "@" sign.0632

And then, for class variables, you have your "@@".0636

I want to show you an example of this using our Book code.0642

Here is our Book class example.0648

First, notice, we have our two spaces.0655

And then, for our method, we also have two spaces here.0658

You will notice our instance variables and our class...they have the "at" sign.0662

But let's say I wanted to add a class instance variable.0670

We can call it publisher.0679

Let's just call it Educator, LLC.0682

Let's say that I want to add that to my summary, so people will know that this book it published by Educator, LLC.0687

I can add this to my summary.0695

What that would display is...when you call up this summary method, it will show Educator, LLC and your description here.0705

Now, you have different reserved keywords in Ruby.0738

You want to make sure you are not using them in your code.0742

There is alias, and, begin, breakcase, class...def is a method, break is if you are in a loop, begin...and I'm sure you have used those--they are big caps, but more commonly you might use any of these words for a name.0744

Those are reserved, so if you can't find--your code is making a hiccup, or you have some kind of issue, it could be because it's one of these words in your code.0766

The next thing is: parentheses are optional.0778

They are sometimes optional, depending on how you look at it.0785

You do not need parentheses in your methods.0788

Functions do not require parentheses.0792

So, here for our method, search for page--there are no parentheses here.0799

But you will notice, here, we do use parentheses; they are actually the exact same method, but they are optional.0806

Here we have a search for page.0815

This is us calling the method; again, no parentheses.0819

My recommendation is, use parentheses if you have questions about it; once you get more flexible and know what you are doing, then you can remove them.0824

Most people coming from other languages actually enjoy using parentheses, and they are known to keep it that way.0834

So, I would suggest just to go with that tactic at the beginning.0840

And here is another example without parentheses: this is a very popular one--we are going to use puts a lot, and notice we don't need the parentheses here--it makes it easier.0845

For this library, to go over the new lines, these are actually statement terminators.0860

We don't have semicolons in the actual code itself.0870

Usually, in other pieces of code, you have a semicolon here that ends the statement.0874

But, in Ruby, it's common to just have the codeline.0880

The new line itself will actually end it.0885

For example, here you have total=x+y.0891

And you will notice that the x doesn't have any semicolon.0895

So x+y is not going to work at all.0903

Let's do an example with the IRB.0911

So, I do total=x+y, which is what we are going to do.0914

Let's do x=100, y=250.0923

That didn't seem to work. Let's try it again.0929

total=x+y.0939

x=100, y=250, total=x+y.0945

So we get our 350; but you notice if I do total=x, it's already returned 100, and if I put +y, then I get 250, and if I put total itself, it's still going to declare just for the x-value.0955

The next thing is, you can continue code pieces with the period.0980

You would think--we just said--new lines are terminators: they end the statement; but in this case they're not.0985

This period tells it, "Hey, continue looking at the next line."0991

We are calling this array new, but it's also pushing introduction to this array.0998

And then we are calling this period...this period says, "OK, we're not ending it; we're going to continue to the next line."1004

Push your body, push down the array, push summary to array.1010

We have this array here that has introduction, we have our body, and we have summary.1016

And you will notice it's very clean--it never ended--it was actually one stem in itself, and it did the job.1047

For this sample--you can still use semicolons.1058

If you like semicolons, declare them, but get used to not using semicolons.1061

We can use multiple statements on a single line with it.1069

For example--this one is broken up into two lines, but if they were a single line, I would be doing two processes on one line.1075

I recommend you don't use this, though.1082

But there are cases where it is useful.1087

I'll show it to you on this next slide.1092

For example, if we have this code block, notice this is all one line.1100

That might not be exactly the same one I want to show you, though.1109

Let's go back to our Ruby Interpreter.1114

Let's say I'm doing a process, declaring a value to x, a value to y, and then I want to do total=x+y.1117

Notice, I want to show you that even when I enter the semicolon here, it does continue to the next line down.1135

So it hasn't ended the actual statement yet.1144

I can actually do puts total.1147

Notice that was all one line.1151

It outputs that for me.1155

Again, if I were to just do x=100, it's still going, so I can output it here.1158

The next part is code blocks.1173

I recommend you only use the one-liner for this one in cases where you have a single statement.1176

You will notice, for this one, I have a bracket, and a bracket here.1184

But the most recommended way to do it is with this "do" and the "end."1188

The reason is it's just much cleaner; notice, when I use these brackets, I can put it all in one line, which is nice.1196

But, if you have multiple statements, you want to use the do x, your put xx, your other statements, and your end.1205

This one here, I would say, is recommended for multiple lines.1215

And with that, we have gone through our Ruby specifics course.1235

Thank you for being with me here, and I will see you in the next one.1239

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