RE: [PHP] Extending classes multiple times
This is what I had thought. I wasn't sure and needed the clarification. Thanks as always! Matt Friedman -Original Message- From: Harshdeep S Jawanda [mailto:[EMAIL PROTECTED]] Sent: Thursday December 6, 2001 1:55 PM To: Matt Friedman Cc: [EMAIL PROTECTED] Subject: Re: [PHP] Extending classes multiple times I am not very sure what your question is, but "multiple inheritance" means that a derived class can inherit (i.e., be derived from) more than one class. In multiple inhericance, you can have: A B | | +---+---+ | C Here, C is simultaneously derived from A & B. You can't have this in single inheritance (which is what the PHP manual is saying). This means that C can be derived from either A or B, not both. The following is always possible, irrespective of whether multiple inheritance is supported or not: A | +-B | +-C | +-D This is three different classes (B, C and D) derived from A. Hope this helps clarify your doubts. --- Matt Friedman <[EMAIL PROTECTED]> wrote: > I had been under the impression that one could extend a class only > once. > That is, if I extend class A with class B I would then not be able to > extend B again with any other class. > > See: http://www.php.net/manual/en/keyword.extends.php > "An extended class is always dependent on a single base class, that > is, > multiple inheritance is not supported. Classes are extended using the > keyword 'extends'." > > With some testing however, it appears that I can extend class B with > class C and class C with class D and so on... > > Am I misinterpreting the manual? I suspect I am. Or is this a new > feature. Thoughts? > > Thanks, > > Matt Friedman > Web Applications Developer > www.SpryNewMedia.com > Email: [EMAIL PROTECTED] > > > > > > -- > PHP General Mailing List (http://www.php.net/) > To unsubscribe, e-mail: [EMAIL PROTECTED] > For additional commands, e-mail: [EMAIL PROTECTED] > To contact the list administrators, e-mail: > [EMAIL PROTECTED] > > > = Please send all emails to my automatically redirecting address: [EMAIL PROTECTED] Regards, Harshdeep S Jawanda [[EMAIL PROTECTED]] __ Do You Yahoo!? Send your FREE holiday greetings online! http://greetings.yahoo.com -- PHP General Mailing List (http://www.php.net/) To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] To contact the list administrators, e-mail: [EMAIL PROTECTED] -- PHP General Mailing List (http://www.php.net/) To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] To contact the list administrators, e-mail: [EMAIL PROTECTED]
Re: [PHP] Extending classes multiple times
I am not very sure what your question is, but "multiple inheritance" means that a derived class can inherit (i.e., be derived from) more than one class. In multiple inhericance, you can have: A B | | +---+---+ | C Here, C is simultaneously derived from A & B. You can't have this in single inheritance (which is what the PHP manual is saying). This means that C can be derived from either A or B, not both. The following is always possible, irrespective of whether multiple inheritance is supported or not: A | +-B | +-C | +-D This is three different classes (B, C and D) derived from A. Hope this helps clarify your doubts. --- Matt Friedman <[EMAIL PROTECTED]> wrote: > I had been under the impression that one could extend a class only > once. > That is, if I extend class A with class B I would then not be able to > extend B again with any other class. > > See: http://www.php.net/manual/en/keyword.extends.php > "An extended class is always dependent on a single base class, that > is, > multiple inheritance is not supported. Classes are extended using the > keyword 'extends'." > > With some testing however, it appears that I can extend class B with > class C and class C with class D and so on... > > Am I misinterpreting the manual? I suspect I am. Or is this a new > feature. Thoughts? > > Thanks, > > Matt Friedman > Web Applications Developer > www.SpryNewMedia.com > Email: [EMAIL PROTECTED] > > > > > > -- > PHP General Mailing List (http://www.php.net/) > To unsubscribe, e-mail: [EMAIL PROTECTED] > For additional commands, e-mail: [EMAIL PROTECTED] > To contact the list administrators, e-mail: > [EMAIL PROTECTED] > > > = Please send all emails to my automatically redirecting address: [EMAIL PROTECTED] Regards, Harshdeep S Jawanda [[EMAIL PROTECTED]] __ Do You Yahoo!? Send your FREE holiday greetings online! http://greetings.yahoo.com -- PHP General Mailing List (http://www.php.net/) To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] To contact the list administrators, e-mail: [EMAIL PROTECTED]
Re: [PHP] Extending classes multiple times
> I had been under the impression that one could extend a class only once.
> That is, if I extend class A with class B I would then not be able to
> extend B again with any other class.
>
> See: http://www.php.net/manual/en/keyword.extends.php
> "An extended class is always dependent on a single base class, that is,
> multiple inheritance is not supported. Classes are extended using the
> keyword 'extends'."
>
> With some testing however, it appears that I can extend class B with
> class C and class C with class D and so on...
>
> Am I misinterpreting the manual? I suspect I am. Or is this a new
> feature. Thoughts?
This is not a new feature. In your example each class only has a single
parent. Multiple Inheritance is when you do something like:
class C extends A,B { ... }
Doing B extends A followed by C extends B is still single inheritance.
-Rasmus
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