[RESOLVED] Usage of ${$variable}

nrg_alpha

Consider the following:

$text1 = 'Hello World!';
$text2 = 'text1';
echo ${$text2};

Ok, so this will output Hello World!

But I have to admit, it has me scratching my head. From a practicality standpoint, is there a good use for this? (not from the standpoint of what values these particular variables hold, but rather the concept / idea behind it all).

Any good examples of where this notation would come in handy?

bradgrafelman

nrg_alpha wrote:
Any good examples of where this notation would come in handy?

Sure, bad design:

$buy_price = 3.01;
$sell_price = 1.98;

if(some_weird_calculation() == $foomagic) {
    $mode = 'buy';
} else {
    $mode = 'sell';
}

// some time later
$total = $quantity * ${$mode . '_price'};

nrg_alpha

Ah yes.. I can start to see this a little more clearly now.. Hadn't thought of it that way.

Thanks for the example.. Just that the samples I ran across baffled me somewhat. I kept wondering, 'why?'

bradgrafelman

I can't remember any examples still relevant; it is certainly a possible that it's just another one of those nifty features-gone-relics type of things over time, such as how register_globals and magic_quotes used to be just so dandy to use...

nrg_alpha

Oh ok, so it isn't in use so much these days? I could see a place for it's use...

$guyName = 'Alex';
$galName = 'Janet';

$mode = (rand(1,10) < 5)? 'guy' : 'gal';
echo 'Your name is ' . ${$mode . 'Name'};

NogDog

I can't think of any place I've seen it used (not that I've seen it a lot) where I wouldn't have used an associative array, instead.

$price['buy'] = 3.01;
$price['sell'] = 1.98;

if(some_weird_calculation() == $foomagic) {
    $mode = 'buy';
} else {
    $mode = 'sell';
}

// some time later
$total = $quantity * $price[$mode];

nrg_alpha

Well, yeah, I suppose you could go that route as well (associative array). I was more or less just trying to wrap my head around the first initial example... I couldn't grasp it's usefulness.