Add swap function.

[adrianb93]

This function swaps the values of two variables.

$startDate = '2040-01-01';
$endDate = '2020-01-01';

if ($endDate < $startDate) {
    swap($startDate, $endDate);
}

echo $startDate; // prints "2020-01-01"
echo $endDate; // prints "2040-01-01"

[calebporzio]

This is a pretty cool lil' function. Two thoughts:

A) is it obvious enough what it does? I think the answer is yes. After all "tap" isn't obvious at all, it just becomes an idiom.
B) what are some other use cases. I can remember needing something like this, just want to make sure it's truly useful, and not just fun to look at.
C) will this be confused with Laravel's Facade::swap? When I first saw the name of the function, I thought it was a helper to swap instances in the container.

I'm truly not opposed to this, just want to talk some things out.

[akiyamaSM]

For the (c) it would be helpful if the name is changed to var_swap()

[adrianb93]

A) I think it's obvious too, it reads really well.
B) I've only ever used it for sorting function parameters for range related things. For example, a period of time class.
C) I just learned what facade swap is. If I was to swap the implementation behind a facade, I think it would be clearer intent to do so through the facade:

Auth::swap(
    resolve(OperatingSystemAuth::class)
);

I don't think that's the type of thing I'd reach for a helper for. I'm open to naming suggestions. I like how swap reads, and how it's short and sweet though.

Also, this isn't similar to Str::wrap() vs str_wrap() argument. In either case, you'd have imported the facade, whereas why I like the str helpers is that it avoids an import.

[adrianb93]

Just wanted to give this another bump. I found another use case for swap(). I was writing this helper function:

function abort_if_caught($code, $exception, $callback = null)
{
    if ($callback === null) {
        swap($exception, $callback);
    }

    try {
        return $callback();
    } catch (Exception $error) {
        if ($exception && $error instanceof $exception === false) {
            throw $error;
        }

        abort($code);
    }
}

I wanted the $excpetion parameter to be optional, but the $callback to be required. If no third parameter was provided, I used the swap function to swap the values of $exception and $callback.

I did this so I could use the helper in one of two ways:

// Without exception specified
return abort_if_caught(400, function () use ($startDate, $endDate) {
    return CollatedFeedbackAction::execute($startDate, $endDate);
});

// With exception specified
return abort_if_caught(400, DateParseException::class, function () use ($startDate, $endDate) {
    return CollatedFeedbackAction::execute($startDate, $endDate);
}); 

[calebporzio]

Good use case - let's do it!