__get and __set for property access in PHP - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define the magic method that is called when reading inaccessible properties.

PHP

<?php
class Person {
    private $data = [];

    public function [1]($name) {
        return $this->data[$name] ?? null;
    }
}
?>

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

A__construct

B__call

C__get

D__set

Attempts:

3 left

💡 Hint

Common Mistakes

Using __set instead of __get for reading properties.

Forgetting the $name parameter.

The __get method is called when reading inaccessible or undefined properties.

2fill in blank

medium

Complete the code to define the magic method that is called when writing to inaccessible properties.

PHP

<?php
class Person {
    private $data = [];

    public function [1]($name, $value) {
        $this->data[$name] = $value;
    }
}
?>

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

A__unset

B__get

C__call

D__set

Attempts:

3 left

💡 Hint

Common Mistakes

Using __get instead of __set for writing properties.

Missing the $value parameter.

The __set method is called when writing to inaccessible or undefined properties.

3fill in blank

hard

Fix the error in the magic method name to correctly handle property reading.

PHP

<?php
class Person {
    private $data = [];

    public function [1]($name) {
        return $this->data[$name] ?? null;
    }
}
?>

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

A__set

B__get

C__gett

D__call

Attempts:

3 left

💡 Hint

Common Mistakes

Misspelling the method as __gett or __gett.

Using __set instead of __get.

The correct magic method name for reading inaccessible properties is __get.

4fill in blank

hard

Fill both blanks to complete the magic methods for property access.

PHP

<?php
class Person {
    private $data = [];

    public function [1]($name) {
        return $this->data[$name] ?? null;
    }

    public function [2]($name, $value) {
        $this->data[$name] = $value;
    }
}
?>

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

A__get

B__set

C__call

D__unset

Attempts:

3 left

💡 Hint

Common Mistakes

Swapping the method names.

Using unrelated magic methods like __call or __unset.

The __get method handles reading inaccessible properties, and __set handles writing to them.

5fill in blank

hard

Fill all three blanks to create a class that uses __get and __set to store and retrieve properties in a private array.

PHP

<?php
class DataStore {
    private $storage = [];

    public function [1]($key) {
        return $this->storage[[2]] ?? null;
    }

    public function [3]($key, $value) {
        $this->storage[$key] = $value;
    }
}
?>

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

A__get

B$key

C__set

D$value

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong variable names inside the array access.

Confusing __get and __set method names.

The __get method uses the $key parameter to access the private storage array. The __set method sets values in the storage.

Practice

1.

What is the main purpose of the __get magic method in PHP?

easy

A. To control reading of inaccessible or undefined properties

B. To delete object properties

C. To initialize object properties automatically

D. To overload methods dynamically

Solution

1. Step 1: Understand the role of __get

   The __get method is called when reading a property that is inaccessible or not defined in the object.

2. Step 2: Compare with other options

   Options B, C, and D describe different behaviors unrelated to __get. Only To control reading of inaccessible or undefined properties correctly describes its purpose.

3. Final Answer:

   To control reading of inaccessible or undefined properties -> Option A

4. Quick Check:

   __get reads missing properties = A [OK]

Hint: Remember __get triggers on reading missing properties [OK]

Common Mistakes:

• Confusing __get with __set
• Thinking __get initializes properties
• Assuming __get deletes properties

2.

Which of the following is the correct syntax to define the __set magic method in a PHP class?

class Example {
    ?
}

easy

A. public function __set($name, $value) { /* code */ }

B. public function __set($value, $name) { /* code */ }

C. public function __set() { /* code */ }

D. public function set($name, $value) { /* code */ }

Solution

1. Step 1: Recall __set method signature

   The __set method must accept two parameters: the property name and the value to assign.

2. Step 2: Check parameter order and method name

   public function __set($name, $value) { /* code */ } correctly uses __set($name, $value). public function __set($value, $name) { /* code */ } reverses parameters, C has no parameters, and D uses wrong method name.

3. Final Answer:

   public function __set($name, $value) { /* code */ } -> Option A

4. Quick Check:

   __set($name, $value) correct signature = B [OK]

Hint: __set always takes property name first, then value [OK]

Common Mistakes:

• Swapping parameter order
• Omitting parameters
• Using wrong method name without double underscore

3.

What will be the output of the following PHP code?

class Test {
    private $data = [];
    public function __set($name, $value) {
        $this->data[$name] = $value;
    }
    public function __get($name) {
        return $this->data[$name] ?? 'Not found';
    }
}

$obj = new Test();
$obj->color = 'red';
echo $obj->color . ' ' . $obj->size;

medium

A. red null

B. red Not found

C. Notice error and red

D. red

Solution

1. Step 1: Understand property setting

   Setting $obj->color = 'red' calls __set, storing 'red' in $data['color'].

2. Step 2: Understand property getting

   Accessing $obj->color returns 'red'. Accessing $obj->size returns 'Not found' because $data['size'] is not set.

3. Final Answer:

   red Not found -> Option B

4. Quick Check:

   Defined property returns value, undefined returns 'Not found' = D [OK]

Hint: Undefined property returns default from __get using ?? operator [OK]

Common Mistakes:

• Expecting undefined property to be empty string
• Ignoring null coalescing operator
• Assuming Notice error on missing array key

4.

Consider this PHP class:

class Sample {
    private $props = [];
    public function __set($name, $value) {
        $this->props[$name] = $value;
    }
    public function __get($name) {
        return $this->props[$name];
    }
}

$obj = new Sample();
echo $obj->missing;

What error will occur and how to fix it?

medium

A. No error; outputs empty string

B. Fatal error; fix by declaring property publicly

C. Parse error; fix by adding return type

D. Undefined index notice; fix by using null coalescing in __get

Solution

1. Step 1: Identify error cause

   Accessing $obj->missing calls __get, which returns $this->props['missing']. Since 'missing' key is not set, PHP raises an undefined index notice.

2. Step 2: Fix the error

   Modify __get to return $this->props[$name] ?? null or a default value to avoid notice.

3. Final Answer:

   Undefined index notice; fix by using null coalescing in __get -> Option D

4. Quick Check:

   Missing key causes notice; use ?? to fix = C [OK]

Hint: Use ?? operator in __get to avoid undefined index notices [OK]

Common Mistakes:

• Ignoring undefined index notices
• Trying to declare missing properties publicly
• Confusing parse errors with runtime notices

5.

You want to create a PHP class that stores any property set dynamically and logs every property read or write. Which implementation correctly uses __get and __set to achieve this?

class Logger {
    private $data = [];
    public function __set($name, $value) {
        // ???
    }
    public function __get($name) {
        // ???
    }
}

hard

A. In __set: echo write log only; in __get: return value without logging

B. In __set: only store value; in __get: return value without logging

C. In __set: store value and echo write log; in __get: echo read log and return value or null

D. In __set: store value and return it; in __get: echo read log only

Solution

1. Step 1: Understand logging requirements

   We must log both property writes and reads, and store values dynamically.

2. Step 2: Check each option's behavior

   In __set: store value and echo write log; in __get: echo read log and return value or null stores the value in $data and echoes a write log in __set, and echoes a read log and returns the stored value or null in __get. This meets all requirements.

3. Final Answer:

   In __set: store value and echo write log; in __get: echo read log and return value or null -> Option C

4. Quick Check:

   Store and log on read/write = A [OK]

Hint: Log inside both __get and __set while storing values [OK]

Common Mistakes:

• Logging only on write or only on read
• Not returning value in __get
• Returning value in __set (which should be void)