mirror of
https://github.com/adambard/learnxinyminutes-docs.git
synced 2024-12-26 18:58:51 +00:00
333 lines
5.8 KiB
Markdown
333 lines
5.8 KiB
Markdown
---
|
||
language: ruby
|
||
filename: learnruby-zh.rb
|
||
lang: zh-cn
|
||
contributors:
|
||
- ["David Underwood", "http://theflyingdeveloper.com"]
|
||
- ["Joel Walden", "http://joelwalden.net"]
|
||
- ["Luke Holder", "http://twitter.com/lukeholder"]
|
||
- ["lidashuang", "https://github.com/lidashuang"]
|
||
translators:
|
||
- ["Lin Xiangyu", "https://github.com/oa414"]
|
||
---
|
||
|
||
```ruby
|
||
# 这是单行注释
|
||
|
||
=begin
|
||
这是多行注释
|
||
没人用这个
|
||
你也不该用
|
||
=end
|
||
|
||
# 首先，也是最重要的，所有东西都是对象
|
||
|
||
# 数字是对象
|
||
|
||
3.class #=> Fixnum
|
||
|
||
3.to_s #=> "3"
|
||
|
||
|
||
# 一些基本的算术符号
|
||
1 + 1 #=> 2
|
||
8 - 1 #=> 7
|
||
10 * 2 #=> 20
|
||
35 / 5 #=> 7
|
||
|
||
# 算术符号只是语法糖而已
|
||
# 实际上是调用对象的方法
|
||
1.+(3) #=> 4
|
||
10.* 5 #=> 50
|
||
|
||
# 特殊的只也是对象
|
||
nil # 空
|
||
true # 真
|
||
false # 假
|
||
|
||
nil.class #=> NilClass
|
||
true.class #=> TrueClass
|
||
false.class #=> FalseClass
|
||
|
||
# 相等运算符
|
||
1 == 1 #=> true
|
||
2 == 1 #=> false
|
||
|
||
# 不等运算符
|
||
1 != 1 #=> false
|
||
2 != 1 #=> true
|
||
!true #=> false
|
||
!false #=> true
|
||
|
||
# 除了false自己，nil是唯一的值为false的对象
|
||
|
||
!nil #=> true
|
||
!false #=> true
|
||
!0 #=> false
|
||
|
||
# 更多比较
|
||
1 < 10 #=> true
|
||
1 > 10 #=> false
|
||
2 <= 2 #=> true
|
||
2 >= 2 #=> true
|
||
|
||
# 字符串是对象
|
||
|
||
'I am a string'.class #=> String
|
||
"I am a string too".class #=> String
|
||
|
||
placeholder = "use string interpolation"
|
||
"I can #{placeholder} when using double quoted strings"
|
||
#=> "I can use string interpolation when using double quoted strings"
|
||
|
||
|
||
# 输出值
|
||
puts "I'm printing!"
|
||
|
||
# 变量
|
||
x = 25 #=> 25
|
||
x #=> 25
|
||
|
||
# 注意赋值语句返回了赋的值
|
||
# 这意味着你可以用多重赋值语句
|
||
|
||
x = y = 10 #=> 10
|
||
x #=> 10
|
||
y #=> 10
|
||
|
||
# 按照惯例，用 snake_case 作为变量名
|
||
snake_case = true
|
||
|
||
# 使用具有描述性的运算符
|
||
path_to_project_root = '/good/name/'
|
||
path = '/bad/name/'
|
||
|
||
# 符号（Symbols，也是对象)
|
||
# 符号是不可变的，内部用整数类型表示的可重用的值。
|
||
# 通常用它代替字符串来有效地表示有意义的值。
|
||
|
||
|
||
:pending.class #=> Symbol
|
||
|
||
status = :pending
|
||
|
||
status == :pending #=> true
|
||
|
||
status == 'pending' #=> false
|
||
|
||
status == :approved #=> false
|
||
|
||
# 数组
|
||
|
||
# 这是一个数组
|
||
[1, 2, 3, 4, 5] #=> [1, 2, 3, 4, 5]
|
||
|
||
# 数组可以包含不同类型的元素
|
||
|
||
array = [1, "hello", false] #=> => [1, "hello", false]
|
||
|
||
# 数组可以被索引
|
||
# 从前面开始
|
||
array[0] #=> 1
|
||
array[12] #=> nil
|
||
|
||
# 像运算符一样，[var]形式的访问
|
||
# 也就是一个语法糖
|
||
# 实际上是调用对象的[] 方法
|
||
array.[] 0 #=> 1
|
||
array.[] 12 #=> nil
|
||
|
||
# 从尾部开始
|
||
array[-1] #=> 5
|
||
|
||
# 同时指定开始的位置和结束的位置
|
||
array[2, 4] #=> [3, 4, 5]
|
||
|
||
# 或者指定一个范围
|
||
array[1..3] #=> [2, 3, 4]
|
||
|
||
# 像这样往数组增加一个元素
|
||
array << 6 #=> [1, 2, 3, 4, 5, 6]
|
||
|
||
# 哈希表是Ruby的键值对的基本数据结构
|
||
# 哈希表由大括号定义
|
||
hash = {'color' => 'green', 'number' => 5}
|
||
|
||
hash.keys #=> ['color', 'number']
|
||
|
||
# 哈希表可以通过键快速地查询
|
||
hash['color'] #=> 'green'
|
||
hash['number'] #=> 5
|
||
|
||
# 查询一个不存在地键将会返回nil
|
||
hash['nothing here'] #=> nil
|
||
|
||
# 用 #each 方法来枚举哈希表:
|
||
hash.each do |k, v|
|
||
puts "#{k} is #{v}"
|
||
end
|
||
|
||
# 从Ruby 1.9开始, 用符号作为键的时候有特别的记号表示:
|
||
|
||
new_hash = { defcon: 3, action: true}
|
||
|
||
new_hash.keys #=> [:defcon, :action]
|
||
|
||
# 小贴士：数组和哈希表都是可枚举的
|
||
# 它们可以共享一些有用的方法，比如each, map, count 等等
|
||
|
||
# 控制流
|
||
|
||
if true
|
||
"if statement"
|
||
elsif false
|
||
"else if, optional"
|
||
else
|
||
"else, also optional"
|
||
end
|
||
|
||
for counter in 1..5
|
||
puts "iteration #{counter}"
|
||
end
|
||
#=> iteration 1
|
||
#=> iteration 2
|
||
#=> iteration 3
|
||
#=> iteration 4
|
||
#=> iteration 5
|
||
|
||
# 然而
|
||
# 没人用for循环
|
||
# 用`each`来代替，就像这样
|
||
|
||
(1..5).each do |counter|
|
||
puts "iteration #{counter}"
|
||
end
|
||
#=> iteration 1
|
||
#=> iteration 2
|
||
#=> iteration 3
|
||
#=> iteration 4
|
||
#=> iteration 5
|
||
|
||
counter = 1
|
||
while counter <= 5 do
|
||
puts "iteration #{counter}"
|
||
counter += 1
|
||
end
|
||
#=> iteration 1
|
||
#=> iteration 2
|
||
#=> iteration 3
|
||
#=> iteration 4
|
||
#=> iteration 5
|
||
|
||
grade = 'B'
|
||
|
||
case grade
|
||
when 'A'
|
||
puts "Way to go kiddo"
|
||
when 'B'
|
||
puts "Better luck next time"
|
||
when 'C'
|
||
puts "You can do better"
|
||
when 'D'
|
||
puts "Scraping through"
|
||
when 'F'
|
||
puts "You failed!"
|
||
else
|
||
puts "Alternative grading system, eh?"
|
||
end
|
||
|
||
# 函数
|
||
|
||
def double(x)
|
||
x * 2
|
||
end
|
||
|
||
# 函数 (以及所有的方法块) 隐式地返回了最后语句的值
|
||
double(2) #=> 4
|
||
|
||
# 当不存在歧义的时候括号是可有可无的
|
||
double 3 #=> 6
|
||
|
||
double double 3 #=> 12
|
||
|
||
def sum(x,y)
|
||
x + y
|
||
end
|
||
|
||
# 方法的参数通过逗号分隔
|
||
sum 3, 4 #=> 7
|
||
|
||
sum sum(3,4), 5 #=> 12
|
||
|
||
# yield
|
||
# 所有的方法都有一个隐式的块参数
|
||
# 可以用yield参数调用
|
||
|
||
def surround
|
||
puts "{"
|
||
yield
|
||
puts "}"
|
||
end
|
||
|
||
surround { puts 'hello world' }
|
||
|
||
# {
|
||
# hello world
|
||
# }
|
||
|
||
|
||
# 用class关键字定义一个类
|
||
class Human
|
||
|
||
# 一个类变量，它被这个类地所有实例变量共享
|
||
@@species = "H. sapiens"
|
||
|
||
# 构造函数
|
||
def initialize(name, age=0)
|
||
# 将参数name的值赋给实例变量@name
|
||
@name = name
|
||
# 如果没有给出age, 那么会采用参数列表中地默认地值
|
||
@age = age
|
||
end
|
||
|
||
# 基本的 setter 方法
|
||
def name=(name)
|
||
@name = name
|
||
end
|
||
|
||
# 基本地 getter 方法
|
||
def name
|
||
@name
|
||
end
|
||
|
||
# 一个类方法以self.开头
|
||
# 它可以被类调用，但不能被类的实例调用
|
||
def self.say(msg)
|
||
puts "#{msg}"
|
||
end
|
||
|
||
def species
|
||
@@species
|
||
end
|
||
|
||
end
|
||
|
||
|
||
# 类的例子
|
||
jim = Human.new("Jim Halpert")
|
||
|
||
dwight = Human.new("Dwight K. Schrute")
|
||
|
||
# 让我们来调用一些方法
|
||
jim.species #=> "H. sapiens"
|
||
jim.name #=> "Jim Halpert"
|
||
jim.name = "Jim Halpert II" #=> "Jim Halpert II"
|
||
jim.name #=> "Jim Halpert II"
|
||
dwight.species #=> "H. sapiens"
|
||
dwight.name #=> "Dwight K. Schrute"
|
||
|
||
# 调用对象的方法
|
||
Human.say("Hi") #=> "Hi"
|
||
|
||
```
|