Re: [Boost-users] [boost] [review][constrained_value] Review of Constrained Value Library begins today

Subject: Re: [Boost-users] [boost] [review][constrained_value] Review of Constrained Value Library begins today
From: Thorsten Ottosen (thorsten.ottosen_at_[hidden])
Date: 2008-12-22 03:50:48

Mika Heiskanen skrev:
> Hello Peter,
> 
> Peter Simons wrote:
> 
>> Invariant failures, however, are unexpected conditions. Invariants are 
>> not
>> supposed to fail. If they do, it's a sign of incorrect program logic or
>> faulty assumptions. Your program will generally not be able to recover 
>> from
>> such an error, hence invariant checking functions like assert() typically
>> abort the process on failure (and generate debugging information, such 
>> as a
>> core dump).
> 
> Thank you for your explanation Peter. However, I do not see why an assert
> should be the first choice when a programming error can be detected by
> the program itself. For example, I would prefer my word processor
> to announce a programming error instead of producing a core dump.
> Am I missing some finer point on the nature of invariants?

That choice is also perfectly valid, and can be easily achieved with 
your own assert macro/error handler function.

However, checking many preconditions/postconditions and invariants at 
runtime can be very expensive.

http://www.artima.com/cppsource/deepspace.html

might be interesting to read.

-Thorsten