Ruby에 대한 치트 시트
9409 단어 rubybeginnersprogramming
다음은 Ruby 코드의 일부 기본 부분에 대한 간략한 참조 및 설명입니다. 이것을 복사하여 코드 편집기에 붙여넣어 색으로 구분하고 읽기 쉽게 하는 것이 좋습니다.
변수 선언
attr_reader :age
# makes "age" something you can only display, not edit (getter method)
attr_writer :name
# makes "name" something you can change, not display (setter method)
attr_accessor :owner
# makes "owner" able to display & edit (getter & setter)
행동 양식
# v default value
def greet_with_default (name="programmer")
puts "Hello, #{name}!"
end
# def -> identifies it as a method
# parentheses are optional if not passing data
# last line of a method is the return value unless you put return
# end -> end of method (always needed)
# using keyword arguments make it less likely to break (____:)
def happy_birthday(person:, current_age:)
puts "Happy Birthday, #{person}"
current_age += 1
puts "You are now #{current_age} years old"
end
# call the method with the keywords and values
happy_birthday(current_age: 31, person: "Carmelo Anthony")
def self.method
self.order
end
# ^self refers to class in both because it's in method name
def method
self
end
# ^self refers to an instance because it's not in method name
# initialize without knowing what arguments you have
def initialize (args = nil)
# upon initialization (start) accept (hash), default = nil
if args
# ^ if there is a hash do stuff
# v go through each key in hash
args.each_key do |key, value|
# ^look at key & value
self.class.attr_accessor(key)
# ^ dynamically set methods automatically for all keys
self.send("#{key}=", args[key])
# ^send attribute to the self's class
end
end
end
private
# any methods under "private" cannot be called by explicit receiver (Dog.privatemethod)
# can be called by other methods
클래스
class Dog < Pet
# Dog is inheriting all the stuff from Pet class (separate file)
extend FancyDance::ClassMethods
# get module class methods
include FancyDance::InstanceMethods
# get module instance methods
@@dog_count = 0
# class variable
def initialize
# upon initialization
super
# do *initialize* from inherited file (Pet) first
# can take an argument EX: super(name)
@@dog_count += 1
# add 1 to class variable
end
def get_adopted(owner_name)
self.owner = owner_name
# self refers to the instance of Dog that is being called
end
end
# objects in Dog are accessed by dot notation
fido = Dog.new("Fido")
# fido = new instance of Dog, passing in "Fido" as name
fido.get_adopted("Sophie")
# sets "Sophie" as owner
모듈
module FancyDance
# can nest modules
module InstanceMethods
def twirl
"I'm twirling!"
end
def initialize
self.class.all << self
# put current instance in matching class array
# EX: @@dog_list << self
end
end
module ClassMethods
def metadata
"Dogs love to dance."
end
end
end
fido.twirl
# instance output "I'm twirling!"
Dog.metadata
# class output "Dogs love to dance."
해시
# only use bracket notation
my_hash = { key1: "value1", key2: "value2" }
my_hash[:key2]
# => "value2"
# Equivalent to:
{ :key1 => "value1", :key2 => "value2" }
my_hash.keys
# returns the keys in my_hash
my_hash.values
# returns the values in my_hash
my_hash.empty?
# eval if hash is empty (true/false value)
my_hash.delete(:key1)
# deletes (key1), returns edited hash
my_hash.merge(other_hash)
# returns edited my_hash with other_hash appended
어레이
list.detect{|a| a.name == name}
# returns the first element that matches (array only)
# If no block, then it returns enumerator (name).
list.include? "blah"
# does list include "blah"? true/false value
[1, 2, 3].sum
# => 6 (adds values together)
[1, 1, 2, 3, 3, 5, 5].uniq
# => [1, 2, 3, 5] (returns only unique values)
[1, 3, 400, 7].length
# => 4 (returns number of items in array)
[5, 100, 234, 7, 2].sort
# => [2, 5, 7, 100, 234] (sorts smallest to largest)
[1, 2, 3].reverse
# => [3, 2, 1] (put in reverse order)
list.count
# counts amount of items in list
list.first
# returns first thing in array
list.last
# returns last thing in array
list.push("M&Ms")
list << "M&Ms"
# Both put M&Ms at end of array, returns edited array
list.unshift("Cake")
# puts Cake at beginning of array, returns edited array
list.pop
# removes last item, returns removed item
list.shift
# removes first item, returns removed item
list1.concat(list2)
# combine arrays into original array (list1), returns edited array
문자열
var.gsub(' ', '-')
# substitute space for dash (string only)
first_name, last_name = full_name.split
# default of split is by space (string only)
맵 / 필터 / 찾기 / 정렬
def spicy_foods
[
{ name: 'Green Curry', cuisine: 'Thai', heat_level: 9 },
{ name: 'Buffalo Wings', cuisine: 'American', heat_level: 3 },
{ name: 'Mapo Tofu', cuisine: 'Sichuan', heat_level: 6 }
]
end
#MAP the foods in the list by name, returns array of names
spicy_foods.map{ |food| food[:name] }
# Equivalent to:
spicy_foods.map do |food|
food[:name]
end
#FILTER foods by heat level > 5, returns array of objects
spicy_foods.filter{ |food| food[:heat_level] > 5 }
# Equivalent to:
spicy_foods.filter do |food|
food[:heat_level] > 5
end
#FIND food that = what you are looking for, returns 1 object
spicy_foods.find{ |food| food[:cuisine] == cuisine }
# Equivalent to:
spicy_foods.find do |food|
food[:cuisine] == cuisine
end
#SORT by given key (ASCII value), returns array of objects (no change array)
# (<=>) combined comparison operator, returns:
# 0 if the first operand equals the second,
# -1 if the first operand is less than the second, and
# 1 if the first operand is greater than the second.
# sort method, need 2 objects passed to it
spicy_foods.sort do |food1, food2|
food1[:name] <=> food2[:name]
end
# sort_by only needs 1 element passed to it
spicy_foods.sort_by {|food| food[:heat_level]}
# Equivalent to:
spicy_foods.sort_by do |food|
food[:heat_level]
end
루프
num = 10
until num == 0
puts "#{num}"
num -= 1
end
#until the num = 0, count down
num = 0
while num <= 100
puts "#{num}"
num += 1
end
#while num is <= 100, count up
10.times do |i|
puts "i is: #{i}"
end
# Equivalent to:
10.times { |i| puts "i is: #{i}" }
# v range
(1..20).each do |b|
puts "#{b}"
end
# ^ puts value of b while iterating through range of 1-20
콘솔로 인쇄
puts "Hello World!"
# puts -> console.log() with line break @ end
# makes the data into a string
print "Hello"
# print -> console.log() no line breaks
p [1, 2, 3]
# p -> output data in nicer format by calling .inspect
# equivalent to calling v
# puts [1, 2, 3].inspect
pp [{ id: 1, hello: "World" }, { id: 2, hello: "Ruby" }, { id: 3, hello: "Moon" }, { id: 4, hello: "Learner" }]
# pp -> pretty printing for complex data (nested arrays/hashes)
좋은 참고가 되었길 바랍니다!
아래 의견에 중요한 내용이 누락되었다고 생각되면 알려주십시오.
Reference
이 문제에 관하여(Ruby에 대한 치트 시트), 우리는 이곳에서 더 많은 자료를 발견하고 링크를 클릭하여 보았다 https://dev.to/kdliving14/a-cheat-sheet-for-ruby-1ic8텍스트를 자유롭게 공유하거나 복사할 수 있습니다.하지만 이 문서의 URL은 참조 URL로 남겨 두십시오.
우수한 개발자 콘텐츠 발견에 전념 (Collection and Share based on the CC Protocol.)