Re: Modular Protection vs Assertions ...

bravegag <bravegag@[EMAIL PROTECTED]
> writes:

[...]
> - Shall I leave my potential client modules on their own? they will
> have to figure out what my precondition violations are. This is the
> case when using assertions.

Actually it's "their precondition violations", not "yours". That is they
(the
callers) are responsible for violationg the precondition. For
communicating
modules (not just one Eiffel system), one could allow the "true"
precondition
and add an "if" to catch calling errors. In classical C libraries, a
free(NULL) will not catch that, because that would be an extra test for
every
function call. Maybe you want that.

> 
> - Shall I provide a strict defensive layer i.e. filter modules as
> Bertrand calls it so that whenever my library gets in control I know
> for sure that the input is valid?

Sounds like a good idea: Maybe implement your class the usual Eiffel way,
then
add a class around it that allows any precondition, checks for valid
arguments, then call the implementation if the parameters were OK;
otherwise
signal an error (raise exception (the Java way), or return a failure code
(the
C way)).

Ulrich