An old topic (pun intended)

[Davidson Corry]

On 10/16/2011 9:35 PM, Alex Rønne Petersen wrote:
> On 17-10-2011 02:43, bearophile wrote:
>> Timon Gehr:
>>
>>> Eiffel does not do that either.
>>> (even though it _does_ have a built in deep copy feature)
>>>
>>> We don't have to over-engineer the feature, if somebody needs to
>>> deep-copy an object they can implement it themselves and use
>>> old(obj.deepCopy()).
>>
>> I agree. A shallow prestate is quite better than not having it at all
>> in D.
>>
>> Lately C# has implemented DbC, prestate too. I don't know how, but
>> it's worth taking a look.
>>
>> Bye,
>> bearophile
>
> Just for the record, the documentation is at:
> http://download.microsoft.com/download/C/2/7/C2715F76-F56C-4D37-9231-EF8076B7EC13/userdoc.pdf
>
>
> I agree that having old would be great, even if without deep copying
> (which is probably a terrible idea anyway). Also note that C# doesn't do
> deep copying here.
>
> - Alex

Remember, efficiency is not the point, correctness is. Contract code 
goes away in the release build. (Arguably you might want to keep 
*preconditions* in library code, since they vet your input parameters. 
But in practice those usually go away in release builds as well, even in 
Eiffel.)

-- Dai