On 10/16/2011 07:31 PM, Jonathan M Davis wrote:
On Sunday, October 16, 2011 19:13:09 Timon Gehr wrote:
I don't agree that 'old' is very difficult to implement. Just evaluate
what is inside the 'old' before you enter the in contract, store
somewhere, maybe in hidden local variables, and make the data available
in the out contract. Eiffel's 'old' does not do more than that.
(but perhaps there are implementation details in DMD that make this more
difficult than necessary. I don't know.)
What if you're dealing with a class? You'd need to deep copy the entire object
for it to work. There's no way built into the language to do that (not to
mention that it would be horrifically inefficient).
- Jonathan M Davis
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()).
