为什么将哈希中的此字符串键转换为符号? [英] Why is this string key in a hash converted to a symbol?

问题描述

使用Ruby 2.3:

Using Ruby 2.3:

在示例1中，字符串键"a"自动转换为符号，而在示例2中，它保留为字符串.

In example 1, the string key "a" is automatically converted to a symbol, whereas with example 2, it stays a string.

示例1

{"a": 1}
# => {:a=>1} 

示例2

{"a"=>"c"}
# => {"a"=>"c"}

我认为:与旧式哈希火箭=>语法相同.到底是怎么回事?为什么我从未在Rails中注意到这一点?是HashWithIndifferentAccess掩盖了这一点吗?

I thought : was the same as the old style hash rocket => syntax. What is going on? Why have I never noticed this in Rails? Is it the HashWithIndifferentAccess that is obscuring this?

推荐答案

在Ruby 2.3(.0)中，这些都相同:

In Ruby 2.3(.0), these are all the same:

{:"a" => 1}
{"a": 1},
{:a => 1}
{a: 1} 

它们都翻译成同一件事:a在所有这些情况下都是一个符号.

They all translate to the same thing: a is a symbol in all these cases.

{"a"=>1}是不同的:在这种情况下，a是字符串.

{"a"=>1} is different: a is a string in this case.

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