class modifiers should follow the same modifiers and semantic that methods:
T_PUBLIC, T_PROTECTED and T_PRIVATE should be used.
nowadays all classes are public...
T_PUBLIC: everybody can see it, everybody can subclass it
T_PROTECTED: visible only within its ns, but everybody can subclass it
T_PRIVATE: visible only within the same ns, subclass allowed only within its
ns
namespace A {
class Pub { }
protected class Prot { }
private class Priv { }
}
namespace B {
class Foo extends \A\Prot { } // legal, no matter Foo visibility
class Baz extends \A\Priv { } // error, no matter Baz visibility
new Foo(); // ok
new Baz(); // ok
new \A\Pub(); // ok
new \A\Prot(); // error, class is protected
new \A\Priv(); // error, class is private
}
in the example "A" exposes classes "Pub" and "Prot", but you cannot
instantiate class "Prot"
So... does it mean that class "Priv" cannot be used outside "A"? no, you can
always return a reference.
namespace A {
class F {
static function getE() { return new E; }
}
private class E { }
}
var_dump( \A\F::getE() ); // object \A\E
Martin Scotta
On Wed, Mar 9, 2011 at 3:23 PM, Chad Fulton <chadful...@gmail.com> wrote:
> Hello,
>
> On Wed, Mar 9, 2011 at 10:02 AM, Jarrod Nettles <jnett...@inccrra.org>
> wrote:
> > Interesting question. My gut tells me not (as does three years of C#
> experience). I’m sure that everyone will have a different opinion on this
> but to me it seems taboo that a child class override the visibility of the
> parent class. For example, PHP currently does not allow you to override a
> method with a lower or higher visibility than the parent – I can’t go from
> protected to public or vice versa. Visibility must be maintained throughout
> the class hierarchy.
> >
>
> Actually, class properties and methods can have a higher visibility
> than their parents, just not a lower one.
>
> E.g.:
>
> <?php
>
> error_reporting(E_ALL | E_STRICT);
>
> class foo {
> protected function bar() {
>
> }
> }
>
> class baz extends foo {
> public function bar() {
>
> }
> }
>
> class foobar extends baz {
> protected function bar () {
>
> }
> }
>
> ?>
>
> You get the following error:
>
> Fatal error: Access level to foobar::bar() must be public (as in class
> baz) in ...
>
> -------
>
> That said, I wouldn't think that visibility modifiers on classes need
> to follow the same pattern. In the case of properties and methods, I
> think the rationale is that child classes should be compatible from an
> interface standpoint with their parents. That same logic may not
> transfer to class visibility modifiers.
>
> I am certainly no expert, but I'm curious what the use case is for
> class visibility modifiers?
>
> On Wed, Mar 9, 2011 at 7:11 AM, Hannes Landeholm <landeh...@gmail.com>
> wrote:
> > Currently I'm forced to use huge internal classes for my framework
> because
> dividing them into smaller classes would expose internal behavior to the
> "outside"... the application layer.
> >
>
> This doesn't necessarily make sense to me. Isn't it the
> end-developer's problem if they start instantiating classes in weird
> ways?
>
> It doesn't seem the same as having a private method, since in that
> case the end-developer presumably already has an object instance, and
> you want to guide them to the correct interface for interacting with
> it, whereas in an application, one would think that the end-developer
> wouldn't simply be instantiating classes by themselves all over the
> place.
>
> Chad
>
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