retard wrote:
Tue, 01 Dec 2009 14:24:01 -0800, Walter Bright wrote:
Unit tests have their limitations as well. Unit tests cannot prove a
function is pure, for example.
Sure, unit tests can't prove that.
Both unit tests and static verification are needed.
But it doesn't lead to this conclusion. Static verification is sometimes
very expensive
Not if it's built in to the compiler. I aim to bring the cost of it down
to zero.
and real world business applications don't need those
guarantees that often.
Having your accounting software write checks in the wrong amount can be
very very bad. And frankly, if you can afford your software unwittingly
emitting garbage data, you don't need that software for your business apps.
It's ok if a web site or game crashes every now
and then.
If Amazon's web site goes down, they likely lose millions of dollars a
minute. Heck, I once lost a lot of business because the web site link to
the credit card system went down. Few businesses can afford to have
their ecommerce web sites down.
If I need serious static verification, I would use tools like
Coq, not D..
There's a lot of useful stuff in between a total formal proof of
correctness and nothing at all. D can offer proof of various
characteristics that are valuable for eliminating bugs.
