Given the classes below, which function call will NOT cause a type error?

hard📝 Application Q8 of 15

PHP - Inheritance and Polymorphism

class Device {}
class Phone extends Device {}
class Tablet extends Device {}

function useDevice(Device $d) {
    echo "Using device";
}

Choose the correct call:

AuseDevice('Tablet');

BuseDevice(new stdClass());

CuseDevice('Device');

DuseDevice(new Phone());

Step-by-Step Solution

Solution:

Step 1: Understand type hinting with parent class Device
The function accepts Device objects or any subclass instances.
Step 2: Check each call
A and C pass strings (invalid), B passes stdClass (unrelated class, invalid), D passes new Phone() which extends Device (valid).
Final Answer:
useDevice(new Phone()); -> Option D
Quick Check:
Parent class hint accepts parent and subclass objects [OK]

Quick Trick: Parent class hint accepts all subclasses, rejects unrelated types [OK]

Common Mistakes:

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