DIP 45 - approval discussion

[deadalnix]

On Wednesday, 13 November 2013 at 08:48:09 UTC, Jacob Carlborg 
wrote:
> On 2013-11-13 01:36, deadalnix wrote:
>
>> The serialization is a good example. You'll have to note that 
>> if the
>> code has been able to serialize the data, it can generate at 
>> compile
>> time the necessary scafolding to deserialize it.
>
> No, not necessarily. If you serialize an object through a base 
> class reference you currently need to register that with the 
> serializer. The static type information is lost and D doesn't 
> provide enough runtime reflection to get the values of instance 
> variables of an object at runtime.

OK, I see your problem here.

It is a much more general problem than the one solved by the 
factory. For instance, I wanted in the past to write some 
unittest that ensure Liskov's substitution principle (so run the 
unittest on subclasses).

This is fundamentally the same issue : you want to write some 
code that is aware of subclasses. That require somehow to be able 
to mixin something automatically in all subclasses.

Object.factory only solve poorly one instance of this problem.