如何使用Ruby“自我"关键词 [英] How to use the Ruby "self" keyword

问题描述

我无法理解 self 关键字.

I'm having trouble understanding the self keyword.

我理解它是如何用来区分实例方法和类方法的，但是当它在方法内部使用时呢?

I understand how it's used to distinguish between instance methods and class methods but what about when it's used from inside a method?

类似于:

def self.name
  self.name = "TEXT"
end

或

def name2
  self.name = "TEXT2"
end

或

class Array
  def iterate!(&code)
    self.each_with_index do |n, i|
      self[i] = code.call(n)
    end
  end
end

推荐答案

通常，作为接收者的 self 可以省略，在这种情况下，通常最好这样做.但是，在某些情况下，省略 self 会使代码具有其他含义.

Usually, self as a receiver can be omitted, and in such cases, it is usually preferable to do so. However, there are a few cases when omitting self make the code mean something else.

• 一种这样的情况，就像在您的示例 self.name = ... 中一样，使用 setter 方法.Ruby 的语法在方法和变量调用之间存在歧义，当可以解释为变量或方法的东西后跟 = 时，将其解释为局部变量赋值具有优先权.

• One such case is, as in your example self.name = ..., using a setter method. Ruby's syntax is ambiguous between method and variable call, and when something that can be interpreted either as a variable or a method is followed by =, its interpretation as a local variable assignment has priority.

另一种情况是当您想要调用方法 class 时.还有关键字class，对class的解释是关键字优先于方法.

Another case is when you want to call the method class. There is also the keyword class, and interpretation of class as the keyword has priority over it as the method.

还有一种情况是当您想使用方法 [] 时.这种表示法也用于数组字面量，将其解释为数组优先于作为方法的解释.

Still another case is when you want to use the method []. This notation is also used for array literal, and interpretation of it as an array has priority over it as a method.

在每种情况下，您都必须使表达式明确地成为方法调用.一种方法是显式编写接收器，即使它是 self.另一种方式是在方法后写().

In each of these cases, you have to make the expression be unamgiguously a method call. One way is to explicitly write the receiver even when it is self. The other way is to write () after the method.

关于您的示例 self.each_with_index ...，self 可以省略，不建议这样做.

Regarding your example self.each_with_index ..., the self can be omitted, and not doing so is not a recommended practice.

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