How to safely chain methods? [duplicate] - php

Question

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Is there a "nullsafe operator" in PHP?
(3 answers)
Closed 2 years ago.
Is there a way to "safely" chain methods in PHP and simply return null if some previous method returns null? Otherwise, an error would be thrown: trying to get property on non-object;
For example, the following code checks whether a customer's phone number has changed using a QuickBooks SDK. I don't have control over these methods.
$customer->getPrimaryPhone() will always return an object since the form wouldn't have been submitted otherwise, but $old->getPrimaryPhone() may return null if no phone number existed previously.
The following is required to get the phone number:
$old->getPrimaryPhone()->getFreeFormNumber()
If getPrimaryPhone() returns null, then an error would be thrown.
My question is: How would I avoid code repition in the following case?
if (!empty($old->getPrimaryPhone())) {
if ($customer->getPrimaryPhone()->getFreeFormNumber() !== $old->getPrimaryPhone()->getFreeFormNumber()) {
// Repetive code here
}
} else {
// Repetive code here
}

Answer 1

I'd be inclined to implement an equals method on your PhoneNumber class (or whatever it's called). For example
public function equals(PhoneNumber $otherNumber) {
return $otherNumber !== null && $this->getFreeFormNumber() === $otherNumber->getFreeFormNumber();
}
Then you can simply use
if (!$customer->getPrimaryPhone()->equals($old->getPrimaryPhone())
If you've got other logic that needs to be applied (as indicated in your comment about arrays), you can easily implement that in the equals method.