关于 subroutine private to a package 的问题

小帅哥飞飞

In which one of the following ways is a subroutine made private to a particular package?  
Choice 1   
By placing ($$) after the name of the subroutine in the subroutine declaration  
Choice 2   
By placing ($) after the name of the subroutine in the subroutine declaration  
Choice 3   
By prefixing the declaration with the private keyword  
Choice 4   
By creating a locally-scoped reference to an anonymous subroutine  
Choice 5   
By adding the subroutine's name to

哪一个是正确的？
好像Choice 4 可以吗？那么说就是可以用个local 引用指向的匿名子程序？
找到了一点线索从网上如下：
SUBROUTINE can be an expression yielding a reference to code. In this case you can use &${EXPR}([LIST]) or ${EXPR}->([LIST]).

http://66.102.7.104/search?q=cac ... mp;ct=clnk&cd=2

flw

locally-scoped reference 指的是 my 声明的引用。
像这样：

1. my $method = sub {
   
2. # ......
   
3. };

复制代码

小帅哥飞飞

那么哪个选项是正确的？

flw

晕
原来你是要让我帮你做题。

小帅哥飞飞

有疑难请高手解惑嘛。是个BrainBench的题，听过吗？

不要晕倒，还仰仗老大呢。