php Laravel - given a certain argument, call different function

Question

I am building a simple calendar with recurring events.

CalendarEvent.php

id
start_date

CalendarRecurringPattern.php

parent_id
pattern_type // daily, weekly, monthly, yearly ...

Using pattern_type i build each following occurrence starting from start_date, using a recursive function and Carbon::class. What bugs me is the function getNextOccurrence(), I'd like to refactor the if/else block because it's not very clean. Here it is:

use \Carbon\Carbon;
....

public function getNextOccurrence(Carbon $startDate) {

    $pattern_type = $this->getPatternType() // daily, weekly...

    if ($pattern_type == 'daily') {
        $startDate->addDay();
    } else if ($pattern_type == 'weekly') {
        $startDate->addWeek();
    } else if ($pattern_type == 'monthly') {
        $startDate->addMonth();
    } else if ($pattern_type == 'yearly') {
        $startDate->addYear();
    }

}

Thanks!

Answer 1

I don't personally see a problem with the way its currently structured as there aren't that many options, but you could do it a couple of other ways;

Option 1

Array function name mapping (hacky name I just came up with), you could do the following;

$functionMap = [
    "daily" => "addDay",
    "weekly" => "addWeek",
    "monthly" => "addMonth",
    "yearly" => "addYear"
];

if(!isset($functionMap[$pattern_type])){
    throw new \Exception("Can't find patern type $pattern_type", 1);
}

$startDate->$functionMap[$pattern_type]();

This might be seen as a sin by the PHP community but it works none the less

Option 2

You could use a switch which probably isn't a sin by the community.

switch ($pattern_type) {
    case "daily":
        // Do the daily task
        break;
    case "weekly":
        // Do the weekly task
        break;
    case "monthly":
        // Do the monthly task
        break;
    case "yearly":
        // Do the yearly task
        break;
    default: 
        throw new \Exception("Can't find pattern type $pattern_type", 1);
}

Conclusion

I would add some exception / error that can be picked up if a non matched pattern_type is passed.

I would also convert the "magic strings" E.G "daily" to constants in case you need to re-use, change or update them in the future!

In terms of line count;

• your way 10 lines of code
• option 1 11 lines of code
• option 2 15 lines of code

The switch & if statements may have some advantages when doing code analysis aswel where the expected required input values can be picked up.