Re: Shallow vs deep copy (Was Re^3: hash ref mind blow)

[Anonymous Monk]

Yeah, I thought that %{ _ref_ } created an alias, but now I've learned it just shallow copies the struct.

It's coincidental, but everytime I used it as reference passed to subs, I added subkeys and everything worked as an alias. To my surprise, when I added a root key to %copy and it didn't change %hash my world came tumbling down.

So it's back to $$copy->{key} stuff, as

use strict;
local our %copy; 
*copy = \%hash;

Looks so unscoped to my personal perl taste. And Data::Alias will not cpan into my Strawberry perl, complaining about requiring perl 5.8.9 on Win32...

BTW ikegami, wow!

Now... I want to know what package does those hash textgraphs you posted. Cos Data::Dumper doesn't get even close to that kind of representation!

[ikegami]

local our %copy;
*copy = \%hash;

should be

our %copy;
local *copy = \%hash;

Or if you prefer,

local *copy = \%hash;
our %copy;

What's the point of localizing %copy? Depending on whether you do it before or after the aliasing, you either localize a variable you never use, or you localize %hash.

But you do modify *copy, so you should localize that.

I want to know what package does those hash textgraphs you posted.

Notepad.