On 04/17/2005 08:56 AM, Yariv Tal wrote:
Is there a need for a Design by Contract (a.k.a Pre & Post conditions) library? Sure!
[snip]
Unlike many other such libraries it allows for defining all condition types at the begining of the method, instead of making you define the "post" checks just before method exit (which usually constrains you to a single-point-of-method-exit design).
See EXAMPLES below.
Here's a quick summary of condition types:
- Pre conditions - tested immidiately
- Post conditions - tested on exiting the method normally (not due to an exception). You can use both "pre"(=old) values and "post" (=current) values in the test expression (i.e. "pre(size) < post(size)"). If the method returns a value then you can also, with some work on your part, test against it (i.e. "retval > 0").
- Exceptional conditions - tested on exiting the method due to an exception. You can use both "pre" and "post" values in the test expression.
- Delayed Assert - this is just a small add-on that allows you to seperate between an assert's definition time and testing time. It's useful when an assert needs to compare some new value to an "old" value (usually solved by saving the old value in a temp variable, which I find messy).
Sounds great to me.