Why everyone like ruby

Почему все так любят
ruby?
Юрий Хрусталев, Deep Refactoring, 28.09.2016

О чем это?
● О стереотипах
● ruby - удобно, элегантно, просто, понятно
● ruby - инструмент Силиконовой Долины
● ruby лучше, чем python*

Почему?
● Я недавно начал писать на ruby on rails
● До этого я 4 года писал на python
● Wat?
https://www.destroyallsoftware.com/talks/wat

Плохая Махачкала Ruby

class Foo
def initialize
puts 'hi'
end
end

class Foo
def initialize
puts 'hi'
end
end
Foo.new
# А почему метод initialize, не new?

irb(main):001:0> bool
NameError: undefined local variable or method
`bool' for main:Object
from (irb):1
from /usr/bin/irb:12:in `<main>'
# Ок, это же язык с продвинутым ООП

irb(main):002:0> "".to_b
NoMethodError: undefined method `to_b' for
"":String
from (irb):1
# Где метод у объекта, это же ООП язык?

irb(main):003:0> !!""
(irb):2: warning: string literal in condition
=> true
# Почему warning?
# Нужно сравнивать через ==

irb(main):003:0> !!""
(irb):2: warning: string literal in condition
=> true
# Почему warning?
# Нужно сравнивать через ==
# Почему оно true?

irb(main):004:0> !!{}
=> true
irb(main):005:0> !![]

irb(main):004:0> !!{}
=> true
irb(main):005:0> !![]
=> true

irb(main):004:0> !!{}
=> true
irb(main):005:0> !![]
=> true
irb(main):006:0> !!Object.new

irb(main):004:0> !!{}
=> true
irb(main):005:0> !![]
=> true
irb(main):006:0> !!Object.new
=> true
# Ничто не false, кроме false/nil/собственного ==

# Ruby? Это такой DSL для написания Rails-приложений?
irb(main):001:0> require 'active_support/all'
=> true

=> true
irb(main):002:0> [].blank?

=> true
=> true

=> true
=> true
irb(main):003:0> nil.blank?

=> true
=> true
=> true

=> true
=> true
=> true
irb(main):004:0> 0.blank?

=> true
=> true
=> true
=> false

=> true
=> true
=> true
=> false
# нормально же общались

# Python
>>> arr = [1, 2, 3]
>>> map(str, arr)
["1", "2", "3"]

irb(main):001:0> arr = [1, 2, 3]
=> [1, 2, 3]

irb(main):001:0> arr = [1, 2, 3]
=> [1, 2, 3]
irb(main):002:0> arr.map {|item| item.to_s}
=> ["1", "2", "3"]

irb(main):001:0> arr = [1, 2, 3]
=> [1, 2, 3]
irb(main):002:0> arr.map {|item| item.to_s}
=> ["1", "2", "3"]
irb(main):003:0> arr.map(&:to_s)
=> ["1", "2", "3"]
# &: - указатель на имя метода

irb(main):001:0> arr = ["1", "2", "3"]
=> ["1", "2", "3"]

irb(main):001:0> arr = ["1", "2", "3"]
=> ["1", "2", "3"]
irb(main):002:0> arr.map(&:String.new)

irb(main):001:0> arr = ["1", "2", "3"]
=> ["1", "2", "3"]
irb(main):002:0> arr.map(&:String.new)
NoMethodError: undefined method `new' for
:String:Symbol
from (irb):26
# это было бы слишком элегантно

irb(main):003:0> arr.map(&String.method(:new))

irb(main):003:0> arr.map(&String.method(:new))
=> ["1", "2", "3"]
# это удобно

# chain.rb
x =
' foo bar '
.strip
.split(' ')
puts x.to_s

# chain.rb
x =
' foo bar '
.strip
.split(' ')
puts x.to_s
irb(main):001:0> load './chain.rb'
[1, 2]
=> nil

# chain.rb
x =
' foo bar '
#.strip
.split(' ')
puts x.to_s

irb(main):001:0> load './chain.rb'
SyntaxError: /tmp/code.rb:4: syntax error,
unexpected '.', expecting end-of-input
.split(' ')
^
from (irb):15:in `load'
from (irb):15
# даже python так не делает

irb(main):001:0> String.new "x"

=> "x"

=> "x"
irb(main):002:0> String.new("x")

=> "x"
=> "x"

=> "x"
=> "x"
irb(main):003:0> String.new( "x" )

=> "x"
=> "x"
=> "x"

=> "x"
=> "x"
=> "x"
irb(main):004:0> String.new ("x")

=> "x"
=> "x"
=> "x"
irb(main):004:0> String.new ("x")
=> "x"

irb(main):005:0> [String.new("x")]

=> ["x"]

=> ["x"]
irb(main):006:0> [String.new ("x")]

=> ["x"]
irb(main):006:0> [String.new ("x")]
SyntaxError: (irb):25: syntax error, unexpected (
arg, expecting ']'
[String.new ("x")]
^
(irb):25: syntax error, unexpected ']',
expecting end-of-input
# Пробелы

irb(main):001:0> %w(rm -rf /home)

=> ["rm", "-rf", "/home"]

=> ["rm", "-rf", "/home"]
irb(main):002:0> %i(rm -rf /home)

=> ["rm", "-rf", "/home"]
=> [:rm, :"-rf", :"/home"]

=> ["rm", "-rf", "/home"]
=> [:rm, :"-rf", :"/home"]
irb(main):003:0> %x(rm -rf /home)

=> ["rm", "-rf", "/home"]
=> [:rm, :"-rf", :"/home"]
irb(main):003:0> %x(rm -rf /home)
=> ""
# это еще хорошо у меня OSX

irb(main):001:0> {foo: 1}
=> {:foo=>1}

=> {:foo=>1}
irb(main):002:0> {:foo => 1}
=> {:foo=>1}

=> {:foo=>1}
irb(main):002:0> {:foo => 1}
=> {:foo=>1}
irb(main):003:0> {"foo" => 1}
=> {"foo"=>1}

irb(main):005:0> {:foo => 1}["foo"]

irb(main):005:0> {:foo => 1}["foo"]
=> nil

irb(main):005:0> {:foo => 1}["foo"]
=> nil
irb(main):006:0> {:foo => 1}["foo".to_sym]

irb(main):005:0> {:foo => 1}["foo"]
=> nil
irb(main):006:0> {:foo => 1}["foo".to_sym]
=> 1
# зато метод без скобок вызван

irb(main):001:0> h = {:foo => 1}
=> {:foo=>1}

irb(main):001:0> h = {:foo => 1}
=> {:foo=>1}
irb(main):002:0> h = h.with_indifferent_access
=> {"foo"=>1}

irb(main):001:0> h = {:foo => 1}
=> {:foo=>1}
=> {"foo"=>1}
irb(main):003:0> h["foo"]

irb(main):001:0> h = {:foo => 1}
=> {:foo=>1}
=> {"foo"=>1}
=> 1

irb(main):001:0> h = {:foo => 1}
=> {:foo=>1}
=> {"foo"=>1}
=> 1
irb(main):004:0> h[:foo]

irb(main):001:0> h = {:foo => 1}
=> {:foo=>1}
=> {"foo"=>1}
=> 1
=> 1
# доступно только в rails

irb(main):001:0> h = {:foo => 1}
=> {:foo=>1}
=> {"foo"=>1}
=> 1
=> 1
# доступно только в rails
# ruby DSL для rails

def foo(&block)
puts 'open resource'
[*41..42].each &block.method(:call)
puts 'close resource'
end
foo do |value|
puts value
end

def foo(&block)
end
foo do |value|
puts value
end
> open resource
41
42
close resource

def foo(&block)
end
foo do |value|
puts value
break
end

def foo(&block)
end
foo do |value|
puts value
break
end
> open resource
41

def foo(&block)
end
def has_answer?
foo do |value|
return true if value == 42
end
end
puts has_answer?

def foo(&block)
end
def has_answer?
foo do |value|
return true if value == 42
end
end
puts has_answer?
> open resource
true

def foo(&block)
end
def has_answer?
rc = false
foo {|value| rc = true if value == 42}
rc
end
puts has_answer?

def foo(&block)
end
def has_answer?
rc = false
foo {|value| rc = true if value == 42}
rc
end
puts has_answer?
> open resource
close resource
true

module Foo
def bar
puts 'hi'
end
end
irb(main):009:0* Foo.bar

module Foo
def bar
puts 'hi'
end
end
NoMethodError: undefined method `bar' for
Foo:Module
from (irb):9

module Foo
module_function
def bar
puts 'hi'
end
end
hi

module Foo
BAZ = 'hey'
module_function
def bar
puts 'hi'
end
end

module Foo
BAZ = 'hey'
module_function
def bar
puts 'hi'
end
end
irb(main):096:0> Foo::bar

module Foo
BAZ = 'hey'
module_function
def bar
puts 'hi'
end
end
hi
=> nil

module Foo
BAZ = 'hey'
module_function
def bar
puts 'hi'
end
end
hi
=> nil
irb(main):097:0> Foo::BAZ

module Foo
BAZ = 'hey'
module_function
def bar
puts 'hi'
end
end
hi
=> nil
=> "hey"

module Foo
BAZ = 'hey'
module_function
def bar
puts 'hi'
end
end
hi
=> nil
=> "hey"
irb(main):098:0> Foo.baz

module Foo
BAZ = 'hey'
module_function
def bar
puts 'hi'
end
end
hi
=> nil
=> "hey"
irb(main):098:0> Foo.baz
NoMethodError: undefined
method `baz' for Foo:Module
from (irb):98
from /usr/bin/irb:12:in
`<main>'
# почему нет?

В качестве заключения, что с
популярностью ruby?

http://pypl.github.io/PYPL.html

Спасибо за внимание

Why everyone like ruby

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