Re: The IDS, the EDS and the DBMS

I am not sure what you are getting at. I trust you have some axe to grind, so for now I'll just make some aha and hmm remarks so you can check my understanding.

Laconic2 wrote:

> How does Pascal do type checking on the value last assigned to a variable?
> It really doesn't. Pascal knows the type of the variable, and counts on the
> last assignment to have intended to store a value of the correct type. As
> long as Pascal performed the last assignment on behalf of the programmer,
> as is well.

Yes, Pascal determines, analyses and uses the possible dataflows at compiletime. The programmer can rely on just doing run-time type checks on input and compounds.

> But let's say I have an assembly language procedure that simply copies the
> first argument to the second, bit for bit, without regard to type? Call
> it, "cast(a; b)"
>
> Now let's say I have
>
> [code]
> program pearls_before_swine (input; output);
> integer: a;
> real: b, c;
> begin
> readln (a);
> cast (a, b);
> c := float (a);
> writeln (a, b, c)
> end.
> [/code]
>
> I know this is a perverse example. But I have a real interest. Consider a
> language of the Lisp family, that has variables ("atoms") that can be
> assigned values of any type. But you want the benfits of type checking. So
> you do type checking on values at execution time, instead of doing type
> checking on variables at compile time.

So?

> This is kind of far afield of DBMS systems. But if the DBMS, the PL, and
> the network are all integrated into one giant conceptual cosmos, it seems
> to me you have to deal with issues like this.

For most real application development
they are ("integrated into one giant conceptual cosmos"), though not all who make a part can or need to be able to see that - wait! there's that encapsulation thing again. Received on Wed Sep 08 2004 - 21:22:47 CEST