semi-dirty PHP trick?

[metawidget]

How ugly is this approach to making a copy of an array that moves only values, not references?

$copy_of_array = unserialize(serialize($multidimensional_array));

I feel a little dirty... assuming I'm not too worried about efficiency, should I?

Comments

[http://users.livejournal.com/hub_/]

well it is PHP. The language wihtout design.

Even Perl sound sane compared to PHP.

(sorry I don't have a real answer)

[v0idnull.livejournal.com]

$a2 = $a1
$a2 =& $a1

is not the same as $a1 =& $a2;

The first, you make a copy. $a2 is a brand new variable in the table.
The second, $a2 is a reference to the $a1 symbol.

What you're doing, is the same thing as $a2 = $a1. Serialize just makes a textual representation of a variable. when you unserialize a variable, you get an identical copy, just like doing $a2 = $a1.

[metawidget]

Is the brand-new copy brand-new all the way down in $a2 = $a1? From my ActionScript days, I've come to expect anything past the first layer to be references to the original arrays, i.e. if $a1 is {$a11,$a12,$a13} with $a11,$a12,$a13 being composite anything, then $a2 is {$a11,$a12,$a13} (changing $a2[2][2] changes $a1[2][2] as well) whereas I want $a2 to contain copies of them, totally freed of any references to any content of $a1.

[v0idnull.livejournal.com]


$a1[0] = 'hello world';
$a2 = $a1;
$a2[0] = 'foo bar';
echo $a1[0].':'.$a2[0]; // hello world:foo bar

$a2 =& $a1;
$a2[0] = 'foo bar';
echo $a1[0].':'.$a2[0]; // foo bar:foo bar


the = operator means assignment. =& operator means reference.

ecmascript (which is what actionscript/javascript are dervitives of), can be wierd when it comes to references.


var i;
var x;
i = x; // i & x are two seperate variables.

var i;
i = some.global.scope.object; // i is a reference of that object


efficiency

[(Anonymous)]

efficiency and php on the same line?
riiiiiiight...

b

Re: efficiency

[metawidget]

Heh... yeah, I guess I'm off the hook one making this project efficient.

I eventually found out that PHP 4 has easy cloning behaviour, but PHP 5 acts like ECMAScript, with its "composite types are always piles of references" thing. Ick. Maybe I should learn more C and write webpages in it or something.