Why less emphasis on private data?

[Andrea Griffini]

Steven D'Aprano wrote:

> That is total and utter nonsense and displays the most appalling
> misunderstanding of probability, not to mention a shocking lack of common
> sense.

While I agree that the programming job itself is not
a program and hence the "consider any possibility"
simply doesn't make any sense I can find a bit of
truth in the general idea that *in programs* it is
dangerous to be deceived by probability.

When talking about correctness (that should be the
main concern) for a programmer "almost never" means
"yes" and "almost always" means "not" (probability
of course for example kicks in about efficency).

Like I said however this reasoning doesn't work
well applied to the programming process itself
(that is not a program... as programmers are not
CPUs; no matter what bigots of software engineering
approaches are hoping for).
Private variables are about the programming process,
not the program itself; and in my experience the
added value of C++ private machinery is very low
(and the added cost not invisible).
When working in C++ I like much more using
all-public abstract interfaces and module-level
all-public concrete class definitions (the so
called "compiler firewall" idiom).

Another thing on the same "line of though" of
private members (that should "help programmers")
but for which I never ever saw *anything but costs*
is the broken idea of "const correctness" of C++.
Unfortunately that is not something that can be
avoided completely in C++, as it roots in the core
of the language.

Andrea