Web Development Articles
Using PHP Class Interface
In PHP, an interface defines a contract or blueprint that any class implementing it must follow.
It specifies method signatures (the names, parameters, and visibility of methods), however does not implement the methods.
A class that implements an interface must define all of the methods declared in the interface.
Interfaces help achieve abstraction and multiple inheritance (since a class can implement multiple interfaces).
Example:
// Define an interface
interface Employee {
public function clockIn(string $message);
}
// Implement the interface in a class
class Engineer implements Employee {
public function clockIn(string $message) {
echo "Engineer Clock In: " . PHP_EOL;
}
}
// Another class implementing the same interface
class Mechanic implements Employee {
public function clockIn(string $message) {
echo "Mechanic Clock In: " . PHP_EOL;
}
}
// Usage
function processTask(Employee $employee) {
$employee->clockIn("Task has been processed!");
}
// You can swap implementations easily
$engineer = new Engineer();
$mechanic = new Mechanic();
processTask($engineer); // Clock In Engineer
processTask($mechanic); // Clock In Mechanic
What interfaces can contain:
- Method declarations (no body/implementation)
- Constants (e.g. const MAX_LIMIT = 100;)
What interfaces cannot contain:
- Properties/variables
- Constructors with implementation
- Method bodies
Example:
interface ExampleInterface {
// Allowed
public function doSomething();
// Allowed
const VERSION = "1.0";
// Not allowed: properties inside interfaces
// public $name; // This will cause an error
}
How To Use PHP Late Static Binding
self:: vs static:: in PHP is all about inheritance and late static binding. So what is late static binding. When building a child class there may be a static property that overrides that same static property on the parent. So when extending this class you will potentially need access to the property on both classes. The way to do this is through late static binding. You can use the self:: and static:: operators to accomplish this.
self::
- Refers to the class where the method is defined.
- Does not consider inheritance overrides.
static::
- Refers to the class that is actually called at runtime.
- This is called late static binding.
- Allows child classes to override static properties/methods and still be respected.
Example: self:: vs static::
class Animal {
public static $type = "Generic Animal";
public static function getTypeUsingSelf() {
return self::$type; // bound to Animal
}
public static function getTypeUsingStatic() {
return static::$type; // late static binding
}
}
class Dog extends Animal {
public static $type = "Dog";
}
// ------------------- USAGE -------------------
echo Dog::getTypeUsingSelf(); // Output: Generic Animal
echo "<br>";
echo Dog::getTypeUsingStatic(); // Output: Dog
PHP $this, self and parent operators
Sometimes different aspects of object oriented programming can be a little confusing if you can’t picture a use case for them. Three class operators in PHP where usage can be a little confusing at times are $this, self and parent. In this article I will try to break things down and maybe you can see where you can use this in your code. Ok so let’s begin.
1. $this
- Refers to the current object instance.
- You use $this when you want to access properties or methods of the current object.
Example:
class Animal {
public $name;
public function setName($name) {
$this->name = $name; // "this object’s" name
}
public function getName() {
return $this->name; // returns "this object’s" name
}
}
$dog = new Animal();
$dog->setName("Buddy");
echo $dog->getName(); // Output: Buddy
2. self
- Refers to the current class itself, not the instance.
- Used for static methods and static properties.
- Does not depend on an object ($this is not available in static context).
Example:
class MathHelper {
public static $pi = 3.14159;
public static function circleArea($radius) {
return self::$pi * $radius * $radius; // accessing static property with self
}
}
echo MathHelper::circleArea(5); // Output: 78.53975
3. parent
- Refers to the immediate parent class.
- Used when you want to access a method or constructor from the parent class that is overridden in the child.
Example:
class Animal {
public function makeSound() {
return "Some generic animal sound";
}
}
class Dog extends Animal {
public function makeSound() {
// Call parent method, then add more
return parent::makeSound() . " and Woof!";
}
}
$dog = new Dog();
echo $dog->makeSound(); // Output: Some generic animal sound and Woof!
Now to summarize:
- $this refers to an instance of the class. It isn’t available in a static context, therefore cannot be used within a static class function.
- The self:: operator refers to the class-level property. It is used in a static context and refers to the actual class itself.
- The parent:: operator calls the overridden method from the parent class. It’s used in inheritance typically to call an overwritten method on the parent class.
Here is a really good example that should help you concieve these concepts and clear up any confusion.
class Animal {
public $name;
public static $kingdom = "Animalia";
public function __construct($name) {
$this->name = $name; // instance reference
}
public function describe() {
return "I am an animal named {$this->name}.";
}
public static function getKingdom() {
return "Kingdom: " . self::$kingdom; // static reference
}
}
class Dog extends Animal {
public function describe() {
// Use parent to get base description
$base = parent::describe();
// Add Dog-specific description
return $base . " I am also a dog that says Woof!";
}
public function introduce() {
// `$this` calls instance method
return $this->describe();
}
public static function getInfo() {
// `self` calls static property from this class (or parent if not overridden)
return "Dogs belong to " . self::$kingdom;
}
}
// ------------------- USAGE -------------------
// Create an object
$dog = new Dog("Buddy");
// $this -> instance reference
echo $dog->introduce();
// Output: I am an animal named Buddy. I am also a dog that says Woof!
echo "<br>";
// self -> static reference
echo Dog::getInfo();
// Output: Dogs belong to Animalia
echo "<br>";
// parent -> calling parent method inside child
echo $dog->describe();
// Output: I am an animal named Buddy. I am also a dog that says Woof!
echo "<br>";
// static method from parent
echo Animal::getKingdom();
// Output: Kingdom: Animalia
Install and Configure ImageMagick for PHP with brew package manager
This tutorial will show you step-by-step how to use brew package manager to install ImageMagick and then configure it to work with PHP.
First check if ImageMagick already exists. Either command below should do that for you.
brew info imagemagick
If ImageMagick isn't installed you can simply use the command below to install it.
brew install imagemagick
Now we need to setup PHP to use the ImageMagick extension. To do so we can use the pecl package manager.
Check if pkg-config is installed.
brew info pkg-config
If pkg-config isn’t installed run the following command.
Set a few configurations for pecl. Run the following 3 commands.
export PKG_CONFIG_PATH="$(brew --prefix imagemagick)/lib/pkgconfig"
export CPPFLAGS="-I$(brew --prefix imagemagick)/include/ImageMagick-7"
export CFLAGS="-DMAGICKCORE_HDRI_ENABLE=1 -DMAGICKCORE_QUANTUM_DEPTH=16"
Install the pecl imagick extension.
pecl install imagick
Restart PHP with brew.
brew services restart php
Check that gd and imagick extensions are set up properly.
php -m | grep -E "gd|imagick"
And that’s it! You may run into an issue with a non-existing imagick extension. If you have multiple versions of PHP installed and frequently switch between different versions you will need to install the Imagick extension for each PHP version.
Solve Vue.js Component Overload with Parent-Child Patterns
Has your Vue component become a tangled mess? Too much template markup, too many responsibilities, and decreasing maintainability.
Well the solution is to use component composition with parent-child relationships that Vue provides.
In this tutorial, you'll learn to:
1. Refactor effectively breaking up monolithic components into focused children
2. Pass data gracefully using props to send data from parent to child
3. Handle child events by capturing custom events emitted by child components
4. Maintain clean data flow by establishing predictable communication between components
See a real-world example where a parent component delegates UI to a specialized Toolbar child, creating cleaner code and better separation of concerns.
Parent Component:
<template>
<div class="parent-component">
<h2>Evaluate Product</h2>
<Toolbar :message="message" @evaluate-product="evaluate" />
<div class="parent-data">
<p>Total Likes: {{ total.likes }}</p>
<p>Total Dislikes: {{ total.dislikes }}</p>
<p v-if="action">Last Action: {{ action }}</p>
</div>
</div>
</template>
<script>
import Toolbar from './Toolbar.vue';
export default {
name: 'EvaluateComponent',
components: {
Toolbar
},
data(){
return {
total: {
likes: 0,
dislikes: 0
},
message: '',
action: null,
messageTimeout: null
}
},
methods:{
evaluate(task) {
// Clear previous timeout
if (this.messageTimeout) {
clearTimeout(this.messageTimeout);
}
switch(task) {
case 'like':
this.total.likes++;
this.message = "Like incremented successfully!";
this.action = 'like';
break;
case 'dislike':
this.total.dislikes++;
this.message = "Dislike incremented successfully!";
this.action = 'dislike';
break;
}
// Auto-clear message after 3 seconds
this.messageTimeout = setTimeout(() => {
this.message = '';
}, 3000);
}
},
beforeDestroy() {
// Clean up timeout when component is destroyed
if (this.messageTimeout) {
clearTimeout(this.messageTimeout);
}
}
}
</script>
Child Component (Toolbar tag in the parent):
<template>
<div class="child-component">
<div class="message" v-if="messageSet">{{ message }}</div>
<button @click="performEvaluate('like')">Like</button>
<button @click="performEvaluate('dislike')">Dislike</button>
</div>
</template>
<script>
export default {
props: {
message: {
type: String,
default: ''
}
},
data() {
return {
// You can add data properties here if needed
}
},
emits: ['evaluate-product'],
computed: {
messageSet() {
return this.message.length > 0;
}
},
methods: {
performEvaluate(evaluation) {
this.$emit('evaluate-product', evaluation);
}
}
}
</script>
Understanding JavaScript Promise.all()
Promise.all() takes an array of promises and returns a single promise that fulfills when all input promises have been fulfilled, or rejects immediately if any of the input promises reject.
Basic Usage:
// resolve promise1
const promise1 = new Promise((resolve, reject) => {
setTimeout(resolve, 200, "King");
});
// resolve promise2
const promise2 = new Promise((resolve, reject) => {
setTimeout(resolve, 100, "Queen");
});
// Notice that all promises supplied must resolve or an error is
// thrown and the promise will be handled in catch()
Promise.all([promise1, promise2]).then(
(fulfilled) => {
console.log(`All fulfilled: ${fulfilled.length}`);
console.log(fulfilled)
}
).catch(e => console.log(e));
// All fulfilled:
// [ 'King', 'Queen' ]
All Promises Must Resolve:
If any Promise in the chain is rejected, a Promise error is returned and will be handled with Promise.catch(). It’s important to get into a habit of providing a Promise.catch() to handle any rejected results.
// All promises are resolved successfully! An array with resolved results
// from each of the fulfilled promises is provided to the chained
// Promise.then(x => console.log(x)) method.
Promise.all([
Promise.resolve("Success 1"),
Promise.resolve("Success 2"),
Promise.resolve("Success 3")
]).then(results => {
console.log(results); // ['Success 1', 'Success 2', 'Success 3']
});
Handling Rejections Gracefully:
// One promise rejects - all others are ignored
const promise1 = new Promise((resolve, reject) => {
setTimeout(resolve, 200, "King");
});
const promise2 = new Promise((resolve, reject) => {
setTimeout(reject, 100, "Queen rejected!");
});
Promise.all([promise1, promise2])
.then((fulfilled) => {
// This will NOT execute
console.log("All fulfilled");
})
.catch(e => {
console.log("Error:", e); // "Error: Queen rejected!"
});
// Output: "Error: Queen rejected!"
Order of Preservation:
A results array is returned ordered in the sequence in which the promise fulfills in the list. All promises are executed in parallel. The first promise to resolve will be the first element of the return array. Notice in this example the first promise in the supplied promises array is actually the last promise in the return array of resolved promises.
// Order of Preservation
// Results maintain the same order as input promises
Promise.all([
new Promise((resolve, reject) => {
setTimeout(resolve, 100, "First");
}),
Promise.resolve("Second"),
Promise.resolve("Third")
])
.then(results => {
console.log(results[0]); // "Second"
console.log(results[1]); // "Third"
console.log(results[2]); // "First"
});
Immediate Rejection:
Notice slowResolve below continues executing but the results are ignored. It’s handled in Promise.catch()
// If any promise rejects, Promise.all immediately rejects
// without waiting for other promises
const fastResolve = new Promise(resolve =>
setTimeout(resolve, 100, "Fast")
);
const slowResolve = new Promise(resolve =>
setTimeout(resolve, 500, "Slow")
);
const fastReject = new Promise((resolve, reject) =>
setTimeout(reject, 50, "Rejected!")
);
Promise.all([fastResolve, slowResolve, fastReject])
.then(results => {
// Never executes
console.log("Success:", results);
})
.catch(error => {
console.log("Caught:", error); // "Caught: Rejected!"
// Both fastResolve and slowResolve continue executing but its result are ignored
});
Always Include Proper Error Handling:
Promise.all([apiCall1(), apiCall2(), apiCall3()])
.then(([result1, result2, result3]) => {
// Process all results
console.log("All API calls succeeded");
})
.catch(error => {
console.error("One or more API calls failed:", error);
// Handle the error appropriately
});
Parallel Processing
It’s perfect for processing multiple API calls in parallel.
const userId = 123;
const api1 = new Promise(resolve => fetch(`/api/users/${userId}`));
const api2 = new Promise(
resolve => fetch(`/api/users/${userId}/posts`)
);
const api3 = new Promise(
resolve => fetch(`/api/users/${userId}/settings`)
);
Promise.all([
api1,
api2,
api2
])
.then(responses => Promise.all(responses.map(r => r.json())))
.then(([user, posts, settings]) => {
console.log("User profile, posts and settings loaded");
// Use all data
})
.catch(error => {
console.error(error);
});
Promise.all() Summary:
1. Promise.all() waits for all promises to resolve or any to reject
2. Order of results matches the input array order
3. Fast failure - rejects immediately on first rejection
4. Always use .catch() to handle potential rejections
5. Perfect for parallel operations that don't depend on each other
If you need different behavior (like waiting for all promises to settle regardless of outcome), checkout Promise.allSettled().
How to use JavaScript Promise catch()
There are a few ways to take advantage of the Promise catch method. The catch() method is run when the Promise is rejected or throws an error. Return value from a Promise is passed forward to the catch() method. Promises can be chained as well. It simply forwards the return value from the chained Promise to the catch method if the Promise is rejected or an error is thrown.
A basic example of using catch() with a Promise reject:
// using Promise.reject
let rejectPromise = new Promise(function(resolve, reject){
reject("promise rejected")
})
function displayCatch(x) {
console.log(x)
}
rejectPromise.catch(x => displayCatch(x))
A basic example of using catch() by throwing an error from the promise:
// throw an error
let promiseError = new Promise(function(resolve, reject){
throw "throw error"
})
function displayCatch(x) {
console.log(x)
}
promiseError.catch(x => displayCatch(x));
Chained promises. Reject or throw error from chained Promise:
let resolvePromise = new Promise(function(resolve, reject) {
setTimeout(resolve, 50, "resolved chained");
})
function resolveDisplay(x) {
console.log(x)
throw "throw error from chained Promise"
}
function displayCatch(x) {
console.log(x)
}
resolvePromise.then(x => resolveDisplay(x)).catch(x => displayCatch(x))