如何在继承Ruby散列时重写[] =方法？ [英] How can I override the []= method when subclassing a Ruby hash?

问题描述

什么是正确的语法来覆盖 [key] = 语法方法来完成这个任务？我想插入我的代码，然后调用父级方法。

这对C方法可能吗？我从文档中看到，底层方法是

$ $ p $ rb_hash_aset（VALUE hash，VALUE key，VALUE val）


这是如何分配到括号语法的？

解决方案

方法签名是 def [] =（key，val），并且 super 调用父方法。下面是一个完整的例子：

  class MyHash<哈希
 def [] =（key，val）
 printf（key：％s，val：％s\，key，val）
 super（key，val）
 end 
 end 
 
x = MyHash.new 
 
x ['a'] ='hello'
x ['b'] ='world '
 
px 
  

I have a class that extends Hash, and I want to track when a hash key is modified.

What's the right syntax to override the [key]= syntactic method to accomplish this? I want to insert my code, then call the parent method.

Is this possible with the C methods? I see from the docs that the underlying method is

rb_hash_aset(VALUE hash, VALUE key, VALUE val)

How does that get assigned to the bracket syntax?

解决方案

The method signature is def []=(key, val), and super to call the parent method. Here's a full example:

class MyHash < Hash
  def []=(key,val)
    printf("key: %s, val: %s\n", key, val)
    super(key,val)
  end
end

x = MyHash.new

x['a'] = 'hello'
x['b'] = 'world'

p x

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