ruby - 当我在 IRB 中声明时，为什么我的顶级方法在所有类上都是公开的(而不是私有(private)的)？

Question

我目前正在阅读“The Well-Grounded Rubyist”，在第 196 页我看到以下内容:

Suppose you define a method at the top level:

def talk
  puts "Hello"
end

....

A method that you define at the top level is stored as a private instance method of the Object class. The previous code is equivalent to this:

class Object

  private

  def talk
    puts "Hello"
  end
end

...

To illustrate, let's extend the talk example. Here it is again, with some code that exercises it:

puts "Trying 'talk' with no receiver..."
talk
puts "Trying 'talk' with an explicit receiver..."
obj = Object.new
obj.talk

The first call to talk succeeds; the second fails with a fatal error, because it tries to call a private method with an explicit receiver.

我想在我的本地重现这个，所以我把上面的代码放在我创建的 Ruby 文件中。我确实得到了书中提到的结果:

$ ruby talk.rb 
Trying 'talk' with no receiver...
Hello
Trying 'talk' with an explicit receiver...
Traceback (most recent call last):
talk.rb:22:in `<main>': private method `talk' called for #<Object:0x00007f9a8499c3e0> (NoMethodError)

我还尝试了以下方法，它产生了与通过 Ruby 解释器运行代码相同的错误:

irb(main):008:0> load 'talk.rb'
Trying 'talk' with no receiver...
Hello
Trying 'talk' with an explicit receiver...
Traceback (most recent call last):
        4: from /Users/richiethomas/.rbenv/versions/2.5.3/bin/irb:11:in `<main>'
        3: from (irb):8
        2: from (irb):8:in `load'
        1: from talk.rb:22:in `<top (required)>'
NoMethodError (private method `talk' called for #<Object:0x00007ffb219c95e0>)

接下来，我在 irb 中尝试了相同的代码，这次我得到了以下奇怪的结果:

irb(main):001:0> def talk
irb(main):002:1> puts "Hello"
irb(main):003:1> end
=> :talk
irb(main):004:0> puts "Trying 'talk' with no receiver..."
Trying 'talk' with no receiver...
=> nil
irb(main):005:0> talk
Hello
=> nil
irb(main):006:0> puts "Trying 'talk' with an explicit receiver..."
Trying 'talk' with an explicit receiver...
=> nil
irb(main):007:0> Object.new.talk
Hello
=> nil

如您所见，在最后一个代码示例中，我能够调用 Object.new.talk 并让它打印 Hello 就好像 .talk 是 Object 实例上的公共(public)方法。

我的问题是 - 为什么 talk 方法在我直接在 REPL 中实现时在 Object 类上是公共(public)的，但在我在文件中实现它并将其加载到 REPL 中时是私有(private)的(并且还有当我通过 Ruby 解释器直接在我的 CLI 中运行同一个文件时)？

Answer 1

irb 和 pry (旁注:我强烈建议使用后者)调整他们的输入以将所有方法声明为公共(public)的(在 REP 的 E 阶段 循环):

▶ def foo; end
#⇒ :foo
▶ public_methods.grep /foo/
#⇒ [:foo]

就是这样，没有魔法。

---

这样做主要是为了简化在此处定义方法然后希望可以从例如访问它的情况下使用它的场景。那里。在 REPL 中，让一切都可以随处访问是值得的。

def pretty_print; self.inspect; end
class A; ...; end
class B; ...; end

A.new.pretty_print
B.new.pretty_print

玩沙盒的时候不要太在意封装、SRP等。

---

一般来说，这就像用通用助手声明模块并免费将其包含在任何地方。