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Re: BlueJ don't know what i did wrong

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On 27/02/13 10:45, Arved Sandstrom wrote:
> On 02/26/2013 07:30 AM, lipska the kat wrote:
>> On 26/02/13 09:59, Arved Sandstrom wrote:
>>> On 02/26/2013 05:23 AM, lipska the kat wrote:
>>> [ SNIP ]
>>>
>>>> What's the contract of Deque ... a double ended queue?
>>>> That in itself breaks the (humanly acceptable) contract of Queue.
>>>> If a Queue is double ended it's not (conceptually) a Queue is it?
>>>>
>>>> Stack = LIFO
>>>> Queue = FIFO
>>>>
>>>> Anything else isn't
>>> [ SNIP ]
>>>
>>>>
>>>> lipska
>>>>
>>> A deque (double ended queue) is a queue generalization. Despite the
>>> name, a deque is not a queue, but a queue is a deque.
>>
>> You have this the wrong way round I'm afraid.
>> A Deque 'is a' Queue because it extends Queue, you can call Queue
>> methods on Deque but you cannot call Deque methods on Queue.
>> A Queue is most definitely NOT a Deque.
>>
>> These are first year comp sci concepts really.
> [ SNIP ]
>
> You want to read up on generalization and specialization.

On the other hand and discussing C++;

http://www.brpreiss.com/books/opus4/html/page158.html

Specialization
The more general abstraction is the base class and the restricted 
abstraction is the derived class. E.g., when using specialization we 
would derive the class Queue from the class Deque thus:
class Queue : public Deque { ... };
The Queue class interface should restrict access to only those base 
class member functions that are appropriate.

Generalization
The more restricted abstraction is the base class from which the more 
general abstraction is derived. E.g., when using generalization we would 
derive the class Deque from the class Queue thus:
class Deque : public Queue { ... };
The Deque class inherits and generalizes the interface of the Queue class.

appears to be at odds with my earlier assertion

So, does either definition make your assertion

"a deque is not a queue, but a queue is a deque"

true?

No it does not

In the Java programming language, and where Deque extends Queue

a Deque *is* a Queue

and

a Queue *is not* a Deque

regardless of which definition of Specialization and Generalization you use.

lipska

-- 
Lipska the Kat©: Troll hunter, sandbox destroyer
and farscape dreamer of Aeryn Sun

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BlueJ don't know what i did wrong BlueJguywithoutskill <marvin.radke@htp-tel.de> - 2013-02-22 06:03 -0800
  Re: BlueJ don't know what i did wrong Joerg Meier <joergmmeier@arcor.de> - 2013-02-22 15:55 +0100
  Re: BlueJ don't know what i did wrong marvin.radke@htp-tel.de - 2013-02-22 07:13 -0800
    Re: BlueJ don't know what i did wrong Joerg Meier <joergmmeier@arcor.de> - 2013-02-22 16:24 +0100
      Re: BlueJ don't know what i did wrong marvin.radke@htp-tel.de - 2013-02-22 07:31 -0800
      Re: BlueJ don't know what i did wrong Eric Sosman <esosman@comcast-dot-net.invalid> - 2013-02-22 10:50 -0500
  Re: BlueJ don't know what i did wrong markspace <markspace@nospam.nospam> - 2013-02-22 10:43 -0800
  Re: BlueJ don't know what i did wrong marvin.radke@htp-tel.de - 2013-02-24 02:27 -0800
    Re: BlueJ don't know what i did wrong Joerg Meier <joergmmeier@arcor.de> - 2013-02-24 14:54 +0100
      Re: BlueJ don't know what i did wrong marvin.radke@htp-tel.de - 2013-02-24 06:15 -0800
    Re: BlueJ don't know what i did wrong lipska the kat <"nospam at neversurrender dot co dot uk"> - 2013-02-24 15:04 +0000
    Re: BlueJ don't know what i did wrong lipska the kat <"nospam at neversurrender dot co dot uk"> - 2013-02-24 16:29 +0000
      Re: BlueJ don't know what i did wrong Joerg Meier <joergmmeier@arcor.de> - 2013-02-24 18:21 +0100
        Re: BlueJ don't know what i did wrong lipska the kat <"nospam at neversurrender dot co dot uk"> - 2013-02-24 17:43 +0000
          Re: BlueJ don't know what i did wrong Joerg Meier <joergmmeier@arcor.de> - 2013-02-24 20:04 +0100
            Re: BlueJ don't know what i did wrong lipska the kat <"nospam at neversurrender dot co dot uk"> - 2013-02-24 19:24 +0000
              Re: BlueJ don't know what i did wrong marvin.radke@htp-tel.de - 2013-02-25 01:52 -0800
                Re: BlueJ don't know what i did wrong lipska the kat <"nospam at neversurrender dot co dot uk"> - 2013-02-25 11:10 +0000
                Re: BlueJ don't know what i did wrong "John B. Matthews" <nospam@nospam.invalid> - 2013-02-25 07:50 -0500
                Re: BlueJ don't know what i did wrong lipska the kat <"nospam at neversurrender dot co dot uk"> - 2013-02-25 13:35 +0000
                Re: BlueJ don't know what i did wrong "John B. Matthews" <nospam@nospam.invalid> - 2013-02-25 13:52 -0500
                Re: BlueJ don't know what i did wrong lipska the kat <"nospam at neversurrender dot co dot uk"> - 2013-02-25 19:54 +0000
                Re: BlueJ don't know what i did wrong Lew <lewbloch@gmail.com> - 2013-02-25 14:26 -0800
                Re: BlueJ don't know what i did wrong lipska the kat <"nospam at neversurrender dot co dot uk"> - 2013-02-26 09:08 +0000
                Re: BlueJ don't know what i did wrong Arne Vajhøj <arne@vajhoej.dk> - 2013-02-25 22:05 -0500
                Re: BlueJ don't know what i did wrong Arne Vajhøj <arne@vajhoej.dk> - 2013-02-25 22:08 -0500
                Re: BlueJ don't know what i did wrong lipska the kat <"nospam at neversurrender dot co dot uk"> - 2013-02-26 09:23 +0000
                Re: BlueJ don't know what i did wrong Arved Sandstrom <asandstrom2@eastlink.ca> - 2013-02-26 05:59 -0400
                Re: BlueJ don't know what i did wrong lipska the kat <"nospam at neversurrender dot co dot uk"> - 2013-02-26 11:30 +0000
                Re: BlueJ don't know what i did wrong Arved Sandstrom <asandstrom2@eastlink.ca> - 2013-02-27 06:45 -0400
                Re: BlueJ don't know what i did wrong lipska the kat <"nospam at neversurrender dot co dot uk"> - 2013-02-27 11:58 +0000
                Re: BlueJ don't know what i did wrong lipska the kat <"nospam at neversurrender dot co dot uk"> - 2013-02-27 12:24 +0000
                Re: BlueJ don't know what i did wrong Arved Sandstrom <asandstrom2@eastlink.ca> - 2013-02-27 22:40 -0400
                Re: BlueJ don't know what i did wrong lipska the kat <"nospam at neversurrender dot co dot uk"> - 2013-02-28 08:53 +0000
                Re: BlueJ don't know what i did wrong Arved Sandstrom <asandstrom2@eastlink.ca> - 2013-02-28 17:14 -0400
                Re: BlueJ don't know what i did wrong lipska the kat <"nospam at neversurrender dot co dot uk"> - 2013-03-01 08:45 +0000
                Re: BlueJ don't know what i did wrong markspace <markspace@nospam.nospam> - 2013-02-26 08:33 -0800
                Re: BlueJ don't know what i did wrong Arne Vajhøj <arne@vajhoej.dk> - 2013-02-25 22:19 -0500
                Re: BlueJ don't know what i did wrong Arne Vajhøj <arne@vajhoej.dk> - 2013-02-25 22:02 -0500
                Re: BlueJ don't know what i did wrong marvin.radke@htp-tel.de - 2013-02-25 09:54 -0800
                Re: BlueJ don't know what i did wrong lipska the kat <"nospam at neversurrender dot co dot uk"> - 2013-02-25 18:25 +0000
                Re: BlueJ don't know what i did wrong Joerg Meier <joergmmeier@arcor.de> - 2013-02-26 16:13 +0100
                Re: BlueJ don't know what i did wrong lipska the kat <"nospam at neversurrender dot co dot uk"> - 2013-02-26 16:40 +0000
                Re: BlueJ don't know what i did wrong Joerg Meier <joergmmeier@arcor.de> - 2013-02-26 18:19 +0100
                Re: BlueJ don't know what i did wrong markspace <markspace@nospam.nospam> - 2013-02-25 08:34 -0800
    Re: BlueJ don't know what i did wrong Lew <lewbloch@gmail.com> - 2013-02-24 12:38 -0800

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