PHP7 Structs

php7_structs.php

<?php 
/**
 * Ideas for how I'd like to see structs implemented in PHP7
 *
 * In this example, structs are more like lightweight objects that have no 
 * methods, just properties. They can be "instantiated" and all properties will be 
 * null until defined later, as per classes. It is however not possible to set a 
 * value to a property that was not defined in the struct originally. 
 *  
 * Structs can extend other structs, much like classes can. Properties can also 
 * have default values, just as classes can. All properties are public. It is 
 * possible to override previous default property values in the extending struct, 
 * as is done in classes. 
 *  
 * During instantiation, it is possible to set properties in a similar fashion to 
 * defining array keys and values, ie with named arguments. 
 *  
 * Structs are first class. 
 */
namespace antnee;

struct User {
    string $name;
    string $email;
    bool   $active;
    int    $maxLogins;
}

$user = new User;
$user->name = 'Antnee';
$user->email = '[email protected]';
$user->active = true;
$user->maxLogins = 'yes'; // Throw a catchable fatal error - incorrect type
$user->foo = 'bar'; // Throw a catchable fatal error - unknown property

/**
 * Populating a Struct via a _constructor_ looks like a mix of object and array
 */
$user = new User(
    'name' => 'Antnee',
    'email' => '[email protected]',
    'active' => true,
    'maxLogins' => 3,
);

/**
 * Function taking a User struct as an argument
 */
function acceptUserStruct(User $struct): User {
    var_dump($struct);
    return $struct;
}

acceptUserStruct($user);

/**
 * Extending a struct
 */
struct AdminUser extends User {
    int  $maxLogins = -1;
    bool $admin = true;
}

$admin = new AdminUser(
    'name' => 'Antnee',
    'email' => '[email protected]',
    'active' => true
);

echo json_encode($admin);
/* Echoes:
{
    "name": "Antnee",
    "email": "[email protected]",
    "active": true,
    "maxLogins": -1,
    "admin": true
}
*/

/**
 * Pass in _anonymous_ struct as argument
 */
$name = 'Me';
$email = '[email protected]';
$active = true;
$maxLogins = 5;

echo json_encode(
    struct {
        'name'      => $name,
        'email'     => $email,
        'active'    => $active,
        'maxLogins' => $maxLogins,
    }
);

/* Echoes:
{
    "name": "Me",
    "email": "[email protected]",
    "active": true,
    "maxLogins": 5
}
*/

@dshafik and @Rican7 : We've just been looking at the namespacing issue, and we don't feel that it's any worse than the class/interface/trait issue, because:

<?php
class abc{}
interface abc{}

PHP Fatal error: Cannot redeclare class abc in test.php on line 3

<?php
class abc{}
trait abc{}

PHP Fatal error: Cannot redeclare class abc in test.php on line 3

<?php
trait abc{}
class abc{}

PHP Fatal error: Cannot redeclare class abc in test.php on line 3

So you can't have a trait, interface or class in the same namespace with the same name anyway. Not in PHP 5.x anyway. Unsure about PHP 7 (untested), but if it behaves the same then it would be consistent and everyone's happy, yes?

Thanks @gallna for looking into this

love it