Intersection types in practice in PHP - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a function that accepts an argument implementing both LoggerInterface and JsonSerializable.

PHP

<?php
function logData([1] $data): void {
    // function body
}
?>

Drag options to blanks, or click blank then click option'

AJsonSerializable

BLoggerInterface|JsonSerializable

CLoggerInterface&JsonSerializable

DLoggerInterface

Attempts:

3 left

💡 Hint

Common Mistakes

Using | instead of & for intersection types

Specifying only one interface

The intersection type LoggerInterface&JsonSerializable ensures the argument implements both interfaces.

2fill in blank

medium

Complete the code to declare a class that implements both Countable and IteratorAggregate using intersection types in a method parameter.

PHP

<?php
class Collection {
    public function process([1] $item): void {
        // process item
    }
}
?>

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ACountable&IteratorAggregate

BCountable

CCountable|IteratorAggregate

DIteratorAggregate

Attempts:

3 left

💡 Hint

Common Mistakes

Using | instead of &

Using only one interface

The parameter type Countable&IteratorAggregate requires the argument to implement both interfaces.

3fill in blank

hard

Fix the error in the function parameter type declaration to correctly use intersection types.

PHP

<?php
function handle([1] $obj): void {
    // handle object
}
?>

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ATraversable&Countable

BTraversable|Countable

CTraversable

DCountable

Attempts:

3 left

💡 Hint

Common Mistakes

Using | instead of &

Using only one interface

Intersection types use & to require the argument to implement both interfaces.

4fill in blank

hard

Fill both blanks to create a function that accepts an argument implementing both ArrayAccess and JsonSerializable, and returns a string.

PHP

<?php
function exportData([1] $data): [2] {
    return json_encode($data);
}
?>

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AArrayAccess&JsonSerializable

Bstring

Cint

DArrayAccess|JsonSerializable

Attempts:

3 left

💡 Hint

Common Mistakes

Using | instead of &

Wrong return type

The parameter uses intersection type ArrayAccess&JsonSerializable and the return type is string.

5fill in blank

hard

Fill all three blanks to define a function that accepts an argument implementing both Countable and IteratorAggregate, returns an int, and uses a variable to store the count.

PHP

<?php
function countItems([1] $collection): [2] {
    $count = count($collection);
    return [3];
}
?>

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ACountable&IteratorAggregate

Bint

C$count

DCountable|IteratorAggregate

Attempts:

3 left

💡 Hint

Common Mistakes

Using | instead of &

Returning wrong variable or type

The parameter uses intersection type Countable&IteratorAggregate, the return type is int, and the function returns the variable $count.