ruby - 读取/分配实例变量的接受 block

Question

考虑一下:

class Foo
  def secret
    @some_ivar
  end    
end

foo_instance = Foo.new

foo_instance.in_foos_context do
  @some_ivar = "bar"
end

foo_instance.secret
=> "bar"

除了看起来可疑之外，这可能吗？如果是这样，我该如何实现 in_foos_context 方法？

Answer 1

你可以使用instance_eval

class Foo
  def secret
    @some_ivar
  end    

  def in_foos_context(&block)
    instance_eval(&block)
  end
end

foo_instance = Foo.new

foo_instance.in_foos_context do
  @some_ivar = "bar"
end

foo_instance.secret # => "bar"