My body is ugly [Re: Contextualizing keywords]

[Andrei Alexandrescu]

Oliver Hoog wrote:
> Michiel Helvensteijn schrieb:
>> Denis Koroskin wrote:
>>
>>>> Because a function precondition indicates the set of admissible states
>>>> before execution of a function. Emphasis on *before* and *function*.
>>> Allowing them anywhere inside a function body will only improve the
>>> feature.
>>>
>>> BTW, it is already allowed, just use 'debug' instead of 'in':
>>
>> Or just use an assertion without an enclosing scope?
>>
>> The difference between a precondition (in) and an arbitrary assertion 
>> inside
>> the function body is that the precondition is part of the public 
>> interface,
>> whereas the function implementation is not.
>>
>>> TBH, I'd just drop the whole DBC feature from a language, it creates 
>>> more
>>> problems than solves.
>>
>> I, on the other hand, believe it's the future of program verification.
>>
> 
> I also find them very useful with inherited functions.
> That they can be inherited wouldn't be intuitive (and not as easily 
> possible) with an 'in' block nested into the function block.

And that's not even an option for interfaces that have "in" blocks, 
something not implemented.

By and large, my opinion is that either we implement DbC correctly (with 
contract inheritance) or we drop it from the language. As of now it's 
completely redundant.


Andrei