Invariant and pre/post-conditions order

[Walter Bright]

On 1/19/2012 6:37 PM, Steven Schveighoffer wrote:
> I have to disagree on some level with (1). It might not make a difference in
> determining there is a bug, but it makes a difference because failing in the
> out-condition gives you more information, even if the invariant is broken. It
> tells you which function broke the invariant.


No, it doesn't give you more information in the out condition. Furthermore, the 
postcondition and the invariant check entirely different state - the return 
value is not the same thing at all as the instance state. There's no reason to 
believe that one is superior to the other, nor that they are redundant.