Ruby on Rails中的冒号位置.

Question

有什么区别:

1)abc:

2):xyz

3)abc :: xyz

4)abc :: xyz

5)abc:xyz

6):abc => xyz

如果我错过了任何一个,请发帖.

Answer 1

1)abc: 它不能独立存在

2):xyz 它是一个象征

:xyz.class
 => Symbol

3)abc::xyz 它代表命名空间

示例代码:

module ABC
    class Xyz
       def initialize
         @size = 400
       end
    end
end

x = ABC::Xyz.new

4) abc: :xyz

hash = {abc: :xyz} #hash key and value all are symbol. 

5) abc: xyz

xyz = "just a test"
hash = {abc: xyz} #hash key is symbol, value is string. 

6) :abc => xyz

xyz = "just a test"
hash = {:abc => xyz} # same with (5)? just another representation

7)三元运算符 :

abc = 1
xyz = 2
result = abc > xyz ? abc : xyz
=> result = 2