FreeBSD 6.0 and onwards

[Yuval Levy]

Andre Oppermann wrote:
> This doesn't work.  You can't change API/ABI incrementally without
breaking
> applications.

I am no OS expert and there are probably such situation in wich
incrementally changing the API without breaking applications is not feasible
or too hard to think of.

Here a simple example where it works:

A currency converter function is part of a web based application plattform:
converted_amount = conversion (original_amount, original_currency,
converted_currency). Then we realized we might also need to format the
conversion for display. Introduce a fourth argument, a bolean
(format/non-format). The new function was converted_amount = conversion
(original_amount, original_currency, converted_currency, format). By testing
if the fourth argument exists and defaulting to the original behaviour if it
does not we upgraded without breaking the applications.

Granted, this is a very simple example, far from the complexity of an
operating system. It only shows that "this doesn't always work, but
sometimes it could".

Yuval Levy