Shortest way to assign a default value to a variable?

Question

I have this right now to use a cookie value if exists otherwise use a default value:

$default_carat_min = "0.25";
if($_COOKIE["diamond-search_caratMin"])
{
    $default_carat_min = $_COOKIE["diamond-search_caratMin"];
}

I am going to have to do this with a lot of variables, and its going to get really cluttered/ugly. So I am trying to come up with a cleaner way of writing this.

I tried:

$default_carat_min = $_COOKIE["diamond-search_caratMin"] | "0.25";

Which did not work.

I can do this:

$default_carat_min = $_COOKIE["diamond-search_caratMin"] ? $_COOKIE["diamond-search_caratMin"] : "0.25";

But I don't like how I have to repeat the $_COOKIE twice. I am wondering if there is a way to write it something like my 2nd example?

Answer 1

PHP 5.3 added a shortform for the ternary operator:

$default_carat_min = $_COOKIE["diamond-search_caratMin"] ?: "0.25";

Which evaluates to the left side if the left side is true, and evaluates to the right side otherwise.

Prior to 5.3, however, you'd have to use the long form.

Answer 2

I think the question is subjective. I personally think it's better to be verbose and there's nothing wrong with your first form because it is completely obvious what your code does.

It's not like you're limited on the number of lines or size you can use. Are you really saving that much by saving a few key strokes?

If it truly a problem, perhaps trying to reduce the number of variables you're using in the first place would be a better solution

Answer 3

You can use a function :

function set_default(&$var, $default) {
    return isset($var) ? $var : $default;
}

$default_carat_min = set_default($_COOKIE["diamond-search_caratMin"], "0.25");

Answer 4

I agree with Cfreak's answer. I'd rather the code be "obvious".

To add to that though you don't want to have to search your code for every instance of 0.25 (or other values) so i recommend creating a config file if you don't have one and adding this...

DEFINE( 'DEFAULT_CARAT_MIN', 0.25 );
// other defaults

Then include the config file and

if($_COOKIE["diamond-search_caratMin"])
{
    $default_carat_min = $_COOKIE["diamond-search_caratMin"];
}
else {
    $default_carat_min = DEFAULT_CARAT_MIN;
}

you could also use the ternary operator

$default_carat_min = $_COOKIE["diamond-search_caratMin"] ? $_COOKIE["diamond-search_caratMin"] : DEFAULT_CARAT_MIN;