Re^2: Preserve array contents in for() loop

Thanks for the answer, though I had removed the similar code from my question before posting it. :) Could you please elaborate on 'deep copy vs. shallow copy'?

--dda

Comment on Re^2: Preserve array contents in for() loop

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Re^3: Preserve array contents in for() loop by dragonchild (Archbishop) on Sep 21, 2004 at 13:53 UTC
Let's say you have an array of hashes. Well, that's really an array of hash references. If you do `foreach my $x (my @b = @a)`, what you're doing is making a copy of the hash references. So, `$x = 3;` won't affect @a, but `$x->{foo} = 3;` will affect `$a[2]{foo}`, if $x was aliased to the third element in @a, for instance. A deep copy will make a copy of both @a and everything that each element in @a might have, should they be references themselves to stuff, and if that stuff is a reference, etc. ------ We are the carpenters and bricklayers of the Information Age. Then there are Damian modules.... sigh* ... that's not about being less-lazy -- that's about being on some really good drugs -- you know, there is no spoon.* - flyingmoose I shouldn't have to say this, but any code, unless otherwise stated, is untested	[reply] [d/l] [select]

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Re^3: Preserve array contents in for() loop
by dragonchild (Archbishop) on Sep 21, 2004 at 13:53 UTC

foreach my $x (my @b = @a)

$x = 3;

$x->{foo} = 3;

$a[2]{foo}

A deep copy will make a copy of both @a and everything that each element in @a might have, should they be references themselves to stuff, and if that stuff is a reference, etc.

------
We are the carpenters and bricklayers of the Information Age.

Then there are Damian modules.... *sigh* ... that's not about being less-lazy -- that's about being on some really good drugs -- you know, there is no spoon. - flyingmoose

I shouldn't have to say this, but any code, unless otherwise stated, is untested

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