问题描述
我刚刚开始使用 Ruby，我正在阅读Programming Ruby 1.9 - The Pragmatic Programmer's Guide".我遇到了一种叫做符号的东西，但作为一名 PHP 开发人员，我不明白它们的作用和用途.
I have just started using Ruby and I am reading "Programming Ruby 1.9 - The Pragmatic Programmer's Guide". I came across something called symbols, but as a PHP developer I don't understand what they do and what they are good for.
谁能帮我解决这个问题?
Can anyone help me out with this?
推荐答案
根据被调用的事物"来考虑符号很有用.换句话说， :banana 指的是那种叫做香蕉的东西".它们在 Ruby 中被广泛使用，主要用作哈希(关联数组)键.
It's useful to think of symbols in terms of "the thing called." In other words, :banana is referring to "the thing called banana." They're used extensively in Ruby, mostly as Hash (associative array) keys.
它们确实类似于字符串，但在幕后，却大不相同.一个关键的区别是内存中只存在一个特定符号.因此，如果您在代码中引用 :banana 10 次，则只会创建一个 :banana 实例，并且它们都引用了那个实例.这也意味着它们是不可变的.
They really are similar to strings, but behind the scenes, very different. One key difference is that only one of a particular symbol exists in memory. So if you refer to :banana 10 times in your code, only one instance of :banana is created and they all refer to that one. This also implies they're immutable.
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