How do I chain methods in PHP?

Question 1

jQuery lets me chain methods. I also remember seeing the same in PHP so I wrote this:

class cat {
 function meow() {
 echo "meow!";
 }

function purr() {
 echo "purr!";
 }
}

$kitty = new cat;

$kitty->meow()->purr();

I cannot get the chain to work. It generates a fatal error right after the meow.

Question 2

To answer your cat example, your cat's methods need to return $this, which is the current object instance. Then you can chain your methods:

class cat {
 function meow() {
  echo "meow!";
  return $this;
 }

 function purr() {
  echo "purr!";
  return $this;
 }
}

Now you can do:

$kitty = new cat;
$kitty->meow()->purr();

For a really helpful article on the topic, see here: http://www.talkphp.com/advanced-php-programming/1163-php5-method-chaining.html

Question 3

Code example with JSON.stringify:

<html>
    <head>
       <title>jQuery Test</title>
       <script type="text/javascript" src="http://code.jquery.com/jquery-1.9.1.js"></script>
       <script type="text/javascript">
           $(document).ready(function() {
               $("#submit").click(function(){
                   $.ajax({
                       url: "text.php",
                       type: "POST",
                       data: {
                           amount: $("#amount").val(),
                           firstName: $("#firstName").val(),
                           lastName: $("#lastName").val(),
                           email: $("#email").val()
                       },
                       dataType: "JSON",
                       success: function (jsonStr) {
                           $("#result").text(JSON.stringify(jsonStr));
                       }
                   });
               });
           });
       </script>
    </head>

    <body>
        <div id="result"></div>
        <form name="contact" id="contact" method="post">
            Amount: <input type="text" name="amount" id="amount"/><br/>
            firstName: <input type="text" name="firstName" id="firstName"/><br/>
            lastName: <input type="text" name="lastName" id="lastName"/><br/>
            email: <input type="text" name="email" id="email"/><br/>
            <input type="button" value="Get It!" name="submit" id="submit"/>
        </form>
    </body>
</html>

text.php

<?php
    $amount      = $_POST["amount"];
    $firstName   = $_POST["firstName"];
    $lastName    = $_POST["lastName"];
    $email       = $_POST["email"];
    if(isset($amount)){
        $data = array(
            "amount"     => $amount,
            "firstName"  => $firstName,
            "lastName"   => $lastName,
            "email"      => $email
        );
        echo json_encode($data);
    }
?>

Question 4

It's rather simple, really. You have a series of mutator methods that all return the original (or other) object. That way, you can keep calling methods on the returned object.

<?php
class fakeString
{
    private $str;
    function __construct()
    {
        $this->str = "";
    }
    
    function addA()
    {
        $this->str .= "a";
        return $this;
    }
    
    function addB()
    {
        $this->str .= "b";
        return $this;
    }
    
    function getStr()
    {
        return $this->str;
    }
}


$a = new fakeString();


echo $a->addA()->addB()->getStr();

This outputs "ab"

Try it online!

Question 5

The problem is one of delimeters and escaped characters (as others have mentioned). This will work:

$date_regex = '/(0[1-9]|1[012])[- /.](0[1-9]|[12][0-9]|3[01])[- /.](19|20)dd/';

$test_date = '03/22/2010';
if(preg_match($date_regex, $test_date)) {
  echo 'this date is formatted correctly';
} else {
  echo 'this date is not formatted correctly';
}

Note that I added a forward-slash to the beginning and ending of the expression and escapped (with a back-slash) the forward-slashes in the pattern.

To take it one step further, this pattern won't properly extract the year... just the century. You'd need to change it to /(0[1-9]|1[012])[- /.](0[1-9]|[12][0-9]|3[01])[- /.]((?:19|20)dd)/ and (as Jan pointed out below) if you want to make sure the whole string matches (instead of some subset) you'll want to go with something more like /^(0[1-9]|1[012])[- /.](0[1-9]|[12][0-9]|3[01])[- /.]((?:19|20)dd)$/.

As others have mentioned, strtotime() might be a better option if you're just trying to get the date out. It can parse almost any commonly used format and it will give you a unix timestamp. You can use it like this:

$test_date = '03/22/2010';

// get the unix timestamp for the date
$timestamp = strtorime($test_date);

// now you can get the date fields back out with one of the normal date/time functions. example:
$date_array = getdate($timestamp);
echo 'the month is: ' . $date_array['month'];

Question 6

You cannot use Method Chaining with static methods because you cannot return a class level scope (return self won't do). Change your methods to regular methods and return $this in each method you want to allow chaining from.

Notice that you should not use T_PAAMAYIM_NEKUDOTAYIM to access instance methods as it will raise an E_STRICT Notice. Use T_OBJECT_OPERATOR for calling instance methods.

Also see:

Chaining Static Methods in PHP?

How do I chain methods in PHP?

Answers

text.php

php,methods,method-chaining