PHP implementation Chain operation Principle of detailed _php example

There are multiple methods in a class, and when you instantiate the class and call the method only one call, similar:

db.php

<?php

class db
{public
function where ()
{
//code to
} public
function order ()
{
//code here
} public
function limit ()
{
//code here
}

index.php

<?php

$db = new db ();

$db->where ();
$db->order ();

If you want to implement a chained call, add the return $this at the end of the method.

db.php

<?php

class db
{public
function where ()
{
//code this return
$this;
}
Public Function order ()
{
//code this return
$this;
}
Public function limit ()
{
//code
$this;

index.php

<?php

$db = new db ();

$db->where ()->order ()->limit ();

The above PHP implementation chain operation principle is small to share all the content, hope to give you a reference, but also hope that we support the cloud-dwelling community.