Invariants for methods

[bearophile]

Andrei:

>I don't think they have contracts in interfaces, which is where most difficulty lies.<

There is some discussion about this topic at page 11 here:
http://research.microsoft.com/en-us/projects/contracts/userdoc.pdf


>At any rate, it's not that we can't do it, it was just a large effort that we decided to postpone.<

Postponing its solution (to D3, if needed) is good.


>Is there anything wrong with the workaround I suggested?<

We have had a discussion like this many times, about unittests, ranged integers, nonull references, etc, so probably we think about languages in different ways.

Your workaround is an intelligent trick, I was not able to invent it, and it's a solution better than the one I have used to solve it (ghost fields in debug{}).

In my opinion in a language you must not need to use intelligent tricks to solve basic problems (and referring to the old state is one of the important parts of DbC).

Bye,
bearophile