Ruby 类:初始化 self 与 @variable [英] Ruby classes: initialize self vs. @variable

问题描述

有人可以解释在定义类时初始化self"和使用@variables 之间的区别吗?

Can someone explain the difference between initializing "self" and having @variables when defining classes?

这是一个例子

class Child < Parent
  def initialize(self, stuff):
    self.stuff = stuff
    super()
  end
end

那么在这种情况下，我不能用 @stuff 替换 self.stuff 吗?有什么不同?另外，super() 只是意味着 Parent 初始化方法中的任何内容，Child 都应该继承它，对吗?

So in this case, wouldn't I be able to replace self.stuff with @stuff? What's the difference? Also, the super() just means whatever is in the Parent initialize method the Child should just inherit it right?

推荐答案

一般来说，不，self.stuff = stuff 和 @stuff = stuff 是不同的.前者在对象上对 stuff= 进行方法调用，而后者直接设置实例变量.前者调用一个可能是公共的方法(除非在类中明确声明为私有)，而后者总是设置一个私有实例变量.

In general, no, self.stuff = stuff and @stuff = stuff are different. The former makes a method call to stuff= on the object, whereas the latter directly sets an instance variable. The former invokes a method which may be public (unless specifically declared private in the class), whereas the latter is always setting a private instance variable.

通常，它们看起来相同，因为在类上定义 attr_accessor :stuff 是很常见的.attr_accessor 大致相当于以下内容:

Usually, they look the same because it is common to define attr_accessor :stuff on classes. attr_accessor is roughly equivalent to the following:

def stuff
  @stuff
end

def stuff=(s)
  @stuff = s
end

所以在这种情况下，它们在功能上是相同的.但是，可以定义公共接口以允许不同的结果和副作用，这将使这两个分配"明显不同:

So in that case, they are functionally identical. However, it is possible to define the public interface to allow for different results and side-effects, which would make those two "assignments" clearly different:

def stuff
  @stuff_called += 1    # Keeps track of how often this is called, a side effect
  return @stuff
end

def stuff=(s)
  if s.nil?             # Validation, or other side effect. This is not triggered when setting the instance variable directly
    raise "Argument should not be nil"
  end
  @stuff = s
end

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