3. Обекти и класове
stefan = Lecturer.new “Стефан Кънев”
nikolay = Lecturer.new “Николай Бачийски”
Lecture.new ‘15‐10‐2008’, stefan, nikolay

15 мин

Хиперкуб

3. 1415926535 8979323846 2643383279 5028841971 6939937510
5820974944 5923078164 0628620899 8628034825 3421170679
8214808651 3282306647 0938446095 5058223172 5359408128
4811174502 8410270193 8521105559 6446229489 5493038196
4428810975 6659334461 2847564823 3786783165 2712019091
4564856692 3460348610 4543266482 1339360726 0249141273
7245870066 0631558817 4881520920 9628292540 9171536436
7892590360 0113305305 4882046652 1384146951 9415116094
3305727036 5759591953 0921861173 8193261179 3105118548
0744623799 6274956735 1885752724 8912279381 8301194912
9833673362 4406566430 8602139494 6395224737 1907021798
6094370277 0539217176 2931767523 8467481846 7669405132
0005681271 4526356082 7785771342 7577896091 7363717872
1468440901 2249534301 4654958537 1050792279 6892589235
4201995611 2129021960 8640344181 5981362977 4771309960
5187072113 4999999837 2978049951 0597317328 1609631859
5024459455 3469083026 4252230825 3344685035 2619311881

Обекти и класове

class Vector
end
direction = Vector.new

class Vector
def initialize(x, y, z)
@x, @y, @z = x, y, z
end
def length
(@x * @x + @y * @y + @z * @z) ** 0.5
end
def to_s() “(#@x, #@y, #@z)” end
end
orientation = Vector.new 1.0, 0.0, 1.0
puts orientation.length

@name, @age

class Vector
# ...
def x() @x end
def y() @y end
def z() @z end
end
v = Vector.new 1.0, 0.0, 1.0
puts v.x + v.y + v.z()

name=

class Thing
def name=(value)
puts “Name is set to #{value}”
end
end
>> bacon = Thing.new
>> bacon.name = “Bacon”
Name is set to Bacon
>> bacon.name=(“Chunky bacon”)
Name is set to Chunky bacon

dir = Vector.new 1.0, 0.0, 1.0
dir.z = 5.0
dir.x, dir.y = 1.0, ‐1.0

class Vector
# ...
def x=(value)
@x = value
end
def y=(value)
@y = value
end
def z=(value)
@z = value
end
end

class Vector
attr_accessor :x, :y, :z
def initialize(x, y, z)
@x, @y, @z = x, y, z
end
end

attr_accessor

attr_accessor :name
def name(value)
@name
end
def name=(value)
@name = value
end

attr_reader
attr_writer

Meyer’s Uniform
Access Principle

class Person
attr_reader :first, :last
def initialize(first, last)
@first, @last = first, last
end
end

class Person
attr_reader :first, :last
def initialize(first, last)
@first, @last = first, last
end
def business_card
“#@first #@last”
end
end

class Person
attr_reader :first, :last
def initialize(first, last)
@first, @last = first, last
end
def business_card
“#@first #@last”
end
def solve_problem(problem)
until problem.solved? or self.bored?
stare_at problem
try_something_random
end
end
end

class Programmer < Person
end

class Programmer < Person
def solve_problem(problem)
thoughts = self.think_about problem
solution = self.invent_solution thoughts
self.write_tests_about solution
self.implement solution
self.party!
end
end

class SmartGuy < Person
def business_card
super() + “, Ph.D.”
end
end

Няма множествено
наследяване

Статични методи

Методи на класа

Променливи на класа

class Person
def initialize(first, last)
@first, @last = first, last
@@count ||= 0
@@count += 1
end
end

@@count ||= 12

@@count = @@count || 12

class Person
def initialize(first, last)
@first, @last = first, last
@@count ||= 0
@@count += 1
end
def Person.count
@@count
end
end
>> Person.new “Thelonious”, “Monk”
>> Person.new “Glenn”, “Gould”
>> puts Person.count
2

class Person
def self.count
@@count
end
end

Оператори

class Vector
attr_accessor :x, :y, :z
def initialize(x, y, z)
@x, @y, @z = x, y, z
end
def length
(@x * @x + @y * @y + @z * @z) ** 0.5
end
def to_s() “(#@x, #@y, #@z)” end
end

c = a + b
d = c * 7

class Vector
def +(other)
Vector.new self.x + other.x,
self.y + other.y,
self.z + other.z
end
def *(n)
Vector.new @x * n, @y * n, @z * n
end
end

>> a = Vector.new 1.0, 0.0, 0.0
>> b = Vector.new 0.0, 1.0, 0.0
>> puts a + b
(1.0, 1.0, 0.0)
>> puts a + b * 2
(1.0, 2.0, 0.0)

! ~ @+ @‐ ** * /
% + ‐ << >> & |
^ < <= >= > == ===
!= =~ !~ <=>

&& || .. ... ?: = **=
*= /= %= += ‐= >>= <<=
&&= &= ||= |= ^= and not
or

3. Обекти и класове
stefan = Lecturer.new “Стефан Кънев”
nikolay = Lecturer.new “Николай Бачийски”
Lecture.new ‘15‐10‐2008’, stefan, nikolay

ДИС‐2

0 = 1

1
∫x dx

1 1 1
∫x dx =
x
x − ∫ x
xd

1 1 1
∫x dx =
x
x − ∫ x
xd =
1
= 1 − ∫ x(− 2 )dx
x

1 1 1
∫x dx =
x
x − ∫ xd
x
=
1 1
= 1 − ∫ x(− 2 )dx = 1 + ∫ dx
x x

1 1 1
∫x dx =
x
x − ∫ xd
x
=
1 1
= 1 − ∫ x(− 2 )dx = 1 + ∫ dx
x x

aquarius@arrakis:$ irb
>> puts 0 == 1
false

Fixnum

class Fixnum
alias broken_equal? ==
end

>> puts 0.broken_equal?(1)
false
>> puts 2.broken_equal?(2)
true

class Fixnum
alias broken_equal? ==
def ==(other)
if (self.equal?(0) and other.equal?(1)) or
(self.equal?(1) and other.equal?(0))
true
else
self.broken_equal?(other)
end
end
end

>> puts 0 == 1
true
>> puts 1 == 1
true
>> puts 2 == 1
false

Александър Макендонски
не е съществувал
Всеки триъгълник
е равностраннен

class Coin
end

class Coin
def initialize(value)
@value = value
end
def pick_up(person)
person.enrich self.value
end
def put_on_train_rail!
self.flatten
end
end

pesho = Coin.new 0.50

pesho = Coin.new 0.50
def pesho.pick_up(person)
person.get_hopes_high
person.humiliate
person.make_sad
end

Хиперкуб

3. 1415926535 8979323846 2643383279 5028841971 6939937510
5820974944 5923078164 0628620899 8628034825 3421170679
8214808651 3282306647 0938446095 5058223172 5359408128
4811174502 8410270193 8521105559 6446229489 5493038196
4428810975 6659334461 2847564823 3786783165 2712019091
4564856692 3460348610 4543266482 1339360726 0249141273
7245870066 0631558817 4881520920 9628292540 9171536436
7892590360 0113305305 4882046652 1384146951 9415116094
3305727036 5759591953 0921861173 8193261179 3105118548
0744623799 6274956735 1885752724 8912279381 8301194912
9833673362 4406566430 8602139494 6395224737 1907021798
6094370277 0539217176 2931767523 8467481846 7669405132
0005681271 4526356082 7785771342 7577896091 7363717872
1468440901 2249534301 4654958537 1050792279 6892589235
4201995611 2129021960 8640344181 5981362977 4771309960
5187072113 4999999837 2978049951 0597317328 1609631859
5024459455 3469083026 4252230825 3344685035 2619311881

pesho = Coin.new 0.50
def pesho.pick_up(person)
person.get_hopes_high
person.humiliate
person.make_sad
end

method_missing
send

method_missing(name, *args)

class Thing
def foo
puts \"I pity the foo!\"
end
def method_missing(name, *args)
puts \"Called #{name} with #{args.inspect}\"
end
end

class Thing
def foo
puts \"I pity the foo!\"
end
def method_missing(name, *args)
puts \"Called #{name} with #{args.inspect}\"
end
end
>> thing = Thing.new
>> thing.foo
I pity the foo
>> thing.larodi 1, \"bar\", []
Called larodi with [1, \"bar\", []]

send

send(name, arg0, arg1, …)

>> people = [\"Monk\", \"Evans\", \"Coltrane\"]
>> puts people.size
3
>> puts people.send(:size)
3
>> people.send :insert, 0, \"Davis“
>> puts people.size
4
>> people.send :<<, \"Rollins“
>> puts people.size
5

class Mapper
def initialize(list)
@list = list
end
def method_missing(name, *args)
@list.map { |x| x.send(name) }
end
end
>> mapper = Mapper.new [\"Coltrane\", \"Evans\", \"Monk\"]
>> mapper.size
[8, 5, 4]
>> puts mapper.downcase
[\"coltrane\", \"evans\", \"monk\"]

class Array
alias old_star *
def *(other = nil)
if other.nil?
Mapper.new self
else
self.old_star(other)
end
end
end

>> people = [\"Coltrane\", \"Evans\", \"Monk\"]
>> people.*.size
[8, 5, 4]
>> people.*.downcase
[\"coltrane\", \"evans\", \"monk\"]
>> people * 2
[\"Coltrane\", \"Evans\", \"Monk\", \"Coltrane\",
\"Evans\", \"Monk\"]

users.*.email