在 Ruby 中冻结符号和数字的用途或效果是什么? [英] What is the use or effect of freezing Symbols and Numbers in Ruby?

问题描述

在 Ruby 1.9 中，您可以拥有未冻结或冻结的 Fixnum、Float 和 Symbol 值:

In Ruby 1.9 you can have Fixnum, Float, and Symbol values that are unfrozen or frozen:

irb(main):001:0> a = [ 17, 42.0, :foo ]; a.map(&:frozen?)
=> [false, false, false]

irb(main):002:0> a.each(&:freeze); a.map(&:frozen?)
=> [true, true, true]

我了解冻结字符串、数组或其他可变数据类型的实用性.然而，据我所知，Fixnum、Symbol 和 Float 实例从一开始就是不可变的.是否有任何理由冻结它们(或者 Ruby 不会将它们报告为已经 frozen 的任何原因?

I understand the utility of freezing strings, arrays, or other mutable data types. As far as I know, however, Fixnum, Symbol, and Float instances are immutable from the start. Is there any reason to freeze them (or any reason that Ruby wouldn't report them as already frozen?

请注意，在 Ruby 2.0 中 Fixnums 和 Floats 都以冻结开始，而 Symbols 保留所描述的行为以上.所以，它正在慢慢变得更好":)

Note that in Ruby 2.0 Fixnums and Floats both start off as frozen, while Symbols retain the behavior described above. So, it's slowly getting 'better' :)

推荐答案

答案是否定的.这些数据类型是不可变的.没有理由冻结这些数据类型.Ruby 没有将这些数据类型报告为冻结的原因是因为 obj.frozen? 方法返回对象的冻结状态，对于不可变数据类型，它最初设置为 false.调用 obj.freeze 会将 freeze 状态设置为该对象的 true.

The answer is no. Those data types are immutable. There is no reason to freeze those datatypes. The reason Ruby does not report those datatypes as frozen is because the obj.frozen? method returns the freeze status of the object and it is set to false initially for immutable datatypes. Calling obj.freeze will set the freeze status to true for that object.

最重要的是，在不可变数据类型上调用 freeze 会将 obj 的 freeze 状态设置为 true，但什么也不做，因为对象已经是不可变的.

The bottom line is that calling freeze on an immutable datatype sets the freeze status of the obj to true, but does nothing because the object is already immutable.

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