[BCB] A class problem -- A die hard challenge

["Shannon S. Harvey" <harv@nospam.netdoor.com>]

Hi Mohammed,
I believe what you are wanting to use (in C++) is templates.
They allow an object to be created of varying types (such as a structure
with varying types of components).
I've included a C++ data structure (a queue implementation) using
templates....hth!


---- Original Message -----
From: Mohammad Iqbal . <mi368@nospam.index.com.jo>
To: <bcb-list@nospam.orionlink.net>
Sent: Saturday, April 24, 1999 7:21 AM
Subject: [BCB] A class problem -- A die hard challenge


> Hi...
>
> The class should simulate dynamic types. We want to design a class whose
> objects could potentially of any reasonably well-behaved type. In other
> words, suppose we want to put objects of several unrelated types into one
> container. How might we arrange for that ability? Designing a  container
> speciffically for this purpose won't do, because we would like to have a
> single design independent of the application.
>
> Note that this is not a part of an assessment or homework or the like. I am
> trying to simulate some good features of the language Eiffel with C++.
> Eiffel support a data type called Any that the compiler doesn't know the
> type of the variable until it is assigned a value. That value determine the
> type of the object.
>
> I think the word 'container' may yield to misunderstanding. What I asking
> for something like the following code
>
> Any three(3);
> Any pi(3.14159);
> int n;
> if (three.extract(n))
>   cout << n << endl;  // prints 3
> pi.extract(n); file://has no effect; yields false
>
> such that three can contain an int value and pi can contain a double value,
> even though three and p have the same type. The extract member obtains data
> from an Any when given a guess as to type that the object contains. Because
> three contains an int, calling three.extract(n) copies the value of that
> int into n and yields true. On the other hand, calling pi.extract(n) yields
> false and has no effect.
>
> Indeed I solved part of the problem. But the most challenging part is to
> overload assignment and copy the values.
>
>
> Mohammad Iqbal

tmplt.cpp