On 30/05/2017 9:52 PM, Charles Mills wrote:
You're trying to scare the poor man!
After I learned OO, I realized the problem in trying to communicate the
concepts.
- The easy-to-grasp explanations are stupid: Animal is a class. Dog and Cat are
child classes of Animal. Fido is an instance of Dog. You could have an
inherited public overridden method Speak() and say myAnimal.Speak() and if it
were a Dog it would bark and if it were a Cat it would Meow ...
Agreed. Inheritance should generally be avoided anyway. It has it's
place but composition should be preferred 9 times out of 10. Inheritance
is tightly coupled and can become incomprehensible once it gets a few
layers deep.
- The real problems that are solved by the significant features are too hard to
explain in a simple tutorial. I solved a problem the other day with a very
sparsely-implemented virtual polymorphic method -- but it would take me an hour
to explain what the problem was.
Polymorphism is the key principle and you don't need an OO language to
use it. Any language with function pointers can implement polymorphism.
A case in point is the z/OS C stdio runtime which supports many
different types of data source. fopen() is the factory function which
populates the read/write (virtual) function pointers in the FILE
structure. There's no reason why you can't write OO code in assembler. I
see lots of assembler code with constitutional logic littered throughout
which call different functions depending on some type which would
benefit from an OO design.
Charles
-----Original Message-----
From: IBM Mainframe Discussion List [mailto:[email protected]] On Behalf
Of David Crayford
Sent: Tuesday, May 30, 2017 5:23 AM
To: [email protected]
Subject: Re: Question about C++
This might bewilder you some more ...
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