Closure is an anonymous function (a function without name. Ex- function (){}) assigned to a variable. When using closure one can use the variable from the immediate parent scope or the variable declared inside the global scope.
It’s essentially employed in coding to reduce the verbosity when writing functions that accept other functions as arguments.
Reducing the size of your code with ‘Closure’ will allow your PHP scripts to load faster and take up less disk space. You may also find that coding in Closure results in programs that are easier to understand and debug. Closure anonymous function makes it possible by reducing complexity, which can be challenging when dealing with dynamic languages like PHP.
Using functions closure in PHP can help to make code more succinct, expressive, and safer.
What are the Uses of Closure?
- Closures are small use-once functions which are useful as parameters for callback functions like array_walk, array_map, etc.
- Using closure functions in PHP can help to make code more succinct, expressive, and safer.
- Closures can access private data of an object.
- Closures can be used in Lazy loading
There are several ways to implement closures in PHP.
The above statement can be executed with the use language construct inside the function.
Syntax:
function() use ($variable) { /* code to be executed */ }
Contents
What is a Closure?
A Closure is a function that can call itself, even when it has finished executing. In other words, Closure is a function that can access variables outside its own scope. This is made possible through a process in which the function remembers and “closes over” its surrounding variables, even after it has finished executing.
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When a function is said to be “closed over” a certain set of variables, what this means is that those variables are in fact “closed” and are no longer in their original scope, but instead exist in the new scope of the function that captured them.
A closure is a function that captures its non-global variables (known as “free variables”) from the execution environment in which it was created. The closure remembers and can use those variables as if it were still executing in that environment. This is a very powerful feature that can greatly increase the expressive power of a programming language.
How to Pass a Variable inside the Closure:
There are two ways to pass a variable inside the closure.
- Pass by value.
- Pass by reference.
Pass By Value:
By passing a variable by value we cannot overwrite the value inside the closure scope.
Example:
<?php
$value = 'this is a car';
function myFunc()
{
$value = 'this is a bus';
$func = function() use ($value)
{
echo $value;
};
$func();
}
myFunc();// this will print this is a bus.
?>
If we overwrite a value inside the closure scope it can’t be resigned because the variable is passed by its value.
Example:
<?php
$value = 'this is a car';
function myFunc()
{
$value = 'this is a bus';
$func = function() use ($value)
{
$value = 'I have a bus';
};
$func();
echo $value; // prints this is a bus!
}
myFunc();
?>
To overcome such situations one can pass the variable by reference.
Pass By Reference:
By passing a variable by reference, the variable can be overwritten inside the closure scope.
Example:
<?php
$value = 'this is a car';
function myFunc()
{
$value = 'this is a bus';
$func = function() use (&amp;$value)
{
$value = 'I have a bus';
};
$func();
echo $value; // prints I have a bus!
}
myFunc();
?>
What is the Difference Between an Anonymous Function and Closure?
An anonymous function or lambda function, and closure are both the instances of Closure class but there is a subtle difference between them. The difference between an anonymous function and closure is that a closure can access a variable outside of its scope by using the keyword.
Advantages of Closure:
The simple advantages of using closure is that when the outer function executes all of its variables still remain in memory until the function completed its execution but in case of closures, the variables declared inside will be released as soon as the closure completed its execution.
Disadvantages of Closure:
As long as closures are active, this memory cannot be garbage collected. Therefore, closures can lead to memory leaks if not used well.
Conclusion
One of the most important aspects of programming is the ability to abstract your code, making it more general and reusable.
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Closures make it possible to write more concise and expressive code, which can help make your code more reusable.
Closures are a powerful tool that can make your code more expressive and easier to read, especially when you have nested functions or lots of logic. This can make it difficult to read and follow the code in certain scenarios.
Closures are a very useful programming tool, but they can also be powerful enough to be dangerous if not used correctly. If you’re not sure how to use them, then please contact us to get clarification or if you just want to make sure you’re using them the right way, then make sure you cross check them before continuing.
Seasoned web developers at Andolasoft leverage PHP programming language using coding best practices that results in creating highly-functional and intuitive web apps for our global customer base.
