In this tutorial we will learn about the closure function in php. Here we will see simple closure using an anonymous function.

Example 1:

// Create a user

$user = "xyz";

// Create a Closure

$invoke = function() use($user) {
  echo "Hello $user";
};

// Greet the user
$invoke(); // Returns "Hello xyz"

Example 2:

// A simple example of a closure

function invoke() {

  $message = "Hello";

  return ( function( $name ) use ( $message ) {
    return ( "$message, $name!" );
  } );
};

$invoke = invoke();
echo $invoke( "abcd" ); // Displays "Hello, abcd!"

As we can see in the above examples, the Closure is able to access the $user/$message variable because it was declared in the use clause of the Closure function definition.

If we alter the $user/$message variable within the Closure, it will not effect the original variable. If we want to update the original variable, we need to prepend an ampersand (& ) to the $user/$message variable as a reference which will updated the original value of $user/$message.

Example3:

// Create a user

$user = "xyz";

// Create a Closure

$invoke = function() use(&$user) {
  echo "Hello $user";
};

$user = "abcd";
// Invoke the user
$invoke(); // Returns "Hello abcd"

Link to create anonymous function