PHP - assigning values in a function argument - good practice?

Question

Setting variable values inside a function call - I don't see this a lot, is this considered good practice?

function myUpdate($status){
    ...
}

myUpdate($status = 'live');

I personally like it because it's more descriptive. I see it more frequently the other way around, ie., assigning a default value in the function definition.

Answer 1

That's a very bad idea, because it's basically code obfuscation. php does not support keyword arguments, and that can lead to weird stuff. Case in point:

function f($a, $b){
    echo 'a: ' . $a . "\n";
    echo 'b: ' . $b . "\n";
}
f($b='b-value', $a='a-value');

This program does not only output

a: b-value
b: a-value

but also defines the variables $b and $a in the global context. This is because

f($b='b-value', $a='a-value');
// is the same thing as ...
$b = 'b-value';
$a = 'a-value';
f($b, $a);

There are a few good practices one can do to make remembering method arguments easier:

• Configure your editor/IDE to show the signature of functions on highlight.
• If a function has lots of arguments that describe some kind of state, consider moving it into an *objec*t (that holds the state instead)
• If your function just needs lots of arguments, make it take an array for all non-essential ones. This also allows the method caller not to worry at all about the multitude of options, she just needs to know the ones she's interested in.

Answer 2

All kidding aside, seriously why do you use it? You have to realize it's something totally different than assigning a default value. What you're doing here is assigning the value to a variable, and then passing that variable to the function. The result is, that after the function call, the $status varialbe is still defined.

myUpdate( $status = 'live' );
echo $status; // "live"

Even if this is what you want, I'd say it's less descriptive than just splitting it out in two lines.