private, protected, readonly, public

> Hello guys,

> after some incantations i came to the attached improved patch that > allows to give properties any visibility plus mark them as public > readable. The patch also implements the PHP 6.0 todo item 'readonly > for overloaded objects'.

> The code now looks like: > <?php > class Test { > private:public $x = 42; > }

> $obj = new Test; > var_dump($obj->x);

> Note, that this adheres to the following EBNF:

> <property> := <write_access>+ (':' <read_access>)? '$' <name> ';' > <write_access> := 'var' | 'public' | 'protected' | 'private' > <read_access> := 'public' > <name> := [_a-zA_Z][_a-zA_Z0-9]*

> Adding 'protected' to <read_access> is possible to but code wise a > tiny bit more complex. Chaging the order is of cause also possible.

> best regards > marcus

> Sunday, May 14, 2006, 11:05:29 AM, you wrote:

>> Hello Jason,

>> Sunday, May 14, 2006, 4:34:03 AM, you wrote:

>>> Hello Marcus,

>>> class x >>> { >>> public readonly $xyz; >>> protected readonly $abc; >>> }

>>> Definitions: >>> - public readonly - outside class can only read, not write. >>> - protected readonly - subclass can only read, not write. >>> - private readonly - does not make sense - do not support.

>>> How difficult would it be to build this into the PHP engine?

>>> -- >>> Best regards, >>> Jason mailto:jason@ionzoft.com

>>> Saturday, May 13, 2006, 5:27:34 AM, you wrote:

>>>>> Hi,

>>>>> my 2c:

>>>>> 1) it shouldn't replace the visibility definition: we could also have >>>>> protected readonly properties.

>>>>> 3) how would you check if the property if readonly ? Trying it could >>>>> result to a Fatal error as you wanted. You would then need a >>>>> isReadonly() method/function: the function call wouldn't be spared.

>> Here's your diff to play around :-) >> The impact on runtime is a single additional integer check for protected >> properties and an additional check for private proeprties where property >> access would normally fail. For this 5 minute patch i chose the key word >> 'readonly' as supposed. Actually writing the mail took much longer than >> brewing the patch and yes i din't care for syntax right now.

>> php -r 'class T{private readonly $x = 42;} $obj = new T; var_dump($obj->x);' >> int(42)

>> Or readable:

>> <?php >> class Test { >> private readonly $x = 42; >> }

>> $obj = new Test; >> var_dump($obj->x);

>> As we have the 'Property overloading RFC' on the 6.0 aganda >> we should probably move part of the stuff to 5.2 already and >> start with the public read access.

>> http://oss.backendmedia.com/PhP60 >> http://www.zend.com/zend/week/week248.php#Heading3

>> Best regards, >> Marcus

> Best regards, > Marcus

> On May 13, 2006, at 7:18 PM, Marcus Boerger wrote: > > > hehe, maybe confused with delphi or borlands c++ > additons? Speaking > > of which before we add 'readonly' we should go for full property > > support but on the other hand that might be a little bit too much > > until php is used with code generators and gui designers where code > > inspectors execute and manipulate source/code while developing. > > Hi Marcus, > > Full property support is high on my wishlist for 6.0. I was a > Delphi programmer for 5 years and miss properties. C#, Ruby, > and Java all have built in property support with accessor > methods, or at least a single standard implementation that > all the tools can get behind. > __get and __set leave you in complete limbo for both source > code and reflection based tools. I think the language > support has to come before the tools. > > I think this can be implemented by adding a getter and setter > field to zend_property_info, then checking for it in > zend_std_read_property, etc. Although, I'm sure there's more > to it than that. Such an implementation would probably be 3 > to 4 times faster than __get(). No switch, no $name > parameter, perhaps no guard logic. Checking for a getter or > setter in zend_property_info would be a fast boolean test on > a data structure thats already available, so I believe there > would be little overhead. > > Here are a few use cases and syntax suggestions... > > A. Declaring a property with accessor methods: > > public $foo read getFoo write setFoo; > > B. Read only property with accessor method could be declared: > > public $foo read getFoo; > > C. A shortcut notation could automatically generate the > accessor method based on another property: > > public $foo read $_foo; > // internally generated method ala C# property implementation: > // public function __get_foo() { return $this->$_foo; } > > D. Similar to read only, you could have split visibility, for > example, a public getter and a protected setter: > > public $foo read getFoo write protected setFoo; // Handy use > case, not crazy about this syntax public function getFoo() { > return $this->_foo; } protected function setFoo($value) { > $this->_foo = $value } > > E. To avoid warnings, declare the internal storage, too: > > public $foo read $_foo write setFoo, protected $_foo; > public $foo read $_foo, protected $_foo; // readonly > > F. Properties with accessor methods cannot be directly initialized. > Their internal storage can, however: > > public $foo read $_foo write setFoo, protected $_foo = 'bar'; > > G. calling unset() on a property with accessor methods could > call the setter with NULL. > > H. calling isset() on a property with accessor methods > returns FALSE if the property does not exist, otherwise calls > the getter and compares against NULL for compatibility purposes. (?) > > I. calling property_exists() on a property with accessor > methods would always return TRUE. > > J. The setter and getter could be inspected via ReflectionProperty. > > K. Unlike __get, subclass property definitions could override > the parent declarations: > > class Foo { public $prop; } > class Bar extends Foo { public $prop read getProp write > setProp; ... } > > L. An abstract class need not declare the actual accessor > methods, they could be added as abstract by default: > > abstract class Bar { public $foo read getFoo write setFoo; } >

> <?php > > class Foo > { > private $bar = 5; > } > > $foo = new Foo(); > echo $foo->bar; // prints 5 > $foo->bar = 4; // error > > ?>