请教一下，如何完整copy一个引用指向的数据结构，如果这个数据结构中仍然有引用。

rick_7

请教一下，如何完整copy一个引用指向的数据结构，如果这个数据结构中仍然有引用。

一个指向hash的引用可以这样copy： $copy = {%{$ds_ref}};

但是如果$ds_ref 指向的数据结构中还有引用，那该如何copy。谢谢

Cu_fans

没看明白，是这个意思吗？

1. use Data::Dumper;
   
2. 
   
3. $hash_ref = {abc => 123,
   
4.              xyz => [456, 789],
   
5.             };
   
6. $ds_ref = $hash_ref;
   
7. $copy = {%{$ds_ref}};
   
8. 
   
9. print Dumper $copy;

复制代码

rick_7

大概可以描述为这样。

1. $ds_ref->{data}=123;
   
2. $ds_ref->{string}="abcd";
   
3. $ds_ref->{child}=$child_ref;
   
4. $child_ref->{data}=456;
   
5. $child_ref->{string}="efgh";
   
6. 
   
7. $copy={%{$ds_ref}};
   

复制代码

希望将$ds_ref指向的整个数据结构完全copy出来。但是上面代码中的如果修改了$child_ref 那么$copy指向的数据结构也会被修改（因为$copy->{child}是一个ref）。难道只能用递归解决么？

zhlong8

猜都可以猜出来要用模块 Clone 吧？

rick_7

谢谢，我去试一下。

moryaden

my $v = eval{Dumper($copy)};

Perl_Er

回复 1# rick_7


   

An array is a defined area of storage for list values, so we can generate a reference to it with the
backslash operator:
$arrayref = \@array;
This produces a reference through which the original array can be accessed and manipulated.
Alternatively, we can make a copy of an array and assign that to a reference by using the array
reference constructor (also known as the anonymous array constructor) [...]:
$copyofarray = [@array];
Both methods give us a reference to an anonymous array that we can assign to, delete from, and modify.
The distinction between the two is important, because one will produce a reference that points to the
original array, and so can be used to pass it to subroutines for manipulations on the original data,
whereas the other will create a copy that can be modified separately.