Re: Very Confused on Page 33

From: Erwin Moller (since_humans_read_this_I_am_spammed_too_much_at_spamyourself.com)
Date: 01/29/05

  • Next message: Andrew Thompson: "Re: Very Confused on Page 33" 
    Date: Sat, 29 Jan 2005 17:36:05 +0100

    Erwin Moller wrote:

    A little correction:

    > eBob.com wrote:
    >
    >> Without getting into what the meaning of is is, am I supposed to
    >> understand that the derived class is the same type as the base class, but
    >> the base class is not the same type as the derived class?
    >
    > Indeed.
    >
    > A cow is an animal.
    > An animal is not (always) a cow.

    Better would be:

    Class Animal...

    Class Cow extends Animal...

    Now we have two types difined: Animal and Cow.

    Both are of type Animal, but onle Cow is of type Cow.

    Regards,
    Erwin Moller

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