Re: Qualified sub-procedures

[Hans Boldt <boldt@xxxxxxxxxx>]

Jim Langston wrote:
> Question on this statement, Hans:
>
>
> > IMHO, OO is not a very good fit for compiled languages like RPG and
> > COBOL and C.  On the other hand, OO really hits its stride in
> > interpreted languages like Object REXX, Python, Smalltalk, and Ruby.
>
> I'm a C++ programmer.  Are you saying that OO is not well done in C++?  Or that it could be better?  Or just what are you saying?
>
> Right now C++ is my langauge of choice, and if it's a bad choice I'd like to know.
I suppose it's primarily a matter of personal choice. Personally, I
prefer the interpreted OO languages (Python in particular) because
of their flexibility and power.

As I noted before, compiled languages tend to have compile-time type
checking. Not that strong typing is necessarily better (although
some would argue that point), it's just that in order to generate
optimal code, compilers like to know the types of things ahead of
time. And so, compiled OO languages tend to have compile-time type
checking, which often means you need to recast pointers to the
proper type.  It also means tricky syntactical features like virtual
classes/functions and interfaces.

On the other hand, in an interpreted language, types are checked at
run-time. Whether or not a particular attribute or method exists for
an object is determined solely at run-time, which greatly simplifies
the design of the language, since you don't need to declare
references as belonging to particular classes, and you never need to
recast the type of an object reference. In addition, interpreted
languages (in some cases) allow you the power of "meta-class
hacking", since a class is an object like any other. That is, you
can create classes on the fly.

Is C++ a bad choice? I think it really depends on the type of
application. For systems programming, it has certainly been used to
good effect. For example, in the Linux world, KDE is implemented in
C++. The big issue with C++ is memory management. Other OO
languages, especially the interpreted ones, have integrated memory
managers with garbage collection. C++ requires you to be more
concerned with memory management issues.

In summary, there are always trade-offs. Compiled OO languages are
generally less powerful, but can generate faster machine code.
Interpreted OO languages are more powerful, but programs (generally)
run slower.

Cheers!  Hans