Time to kill T() as (sometimes) working T.init alias ?

[Jonathan M Davis]

On Sunday, December 09, 2012 13:41:46 Jonathan M Davis wrote:
> Declaring a struct which contains reference types and does a deep copy with
> postblit obviously incurs a performance cost, but it's up to the programmer
> who declared it to decide whether that's worth it or not. I see no reason
> for the language to try and disallow that. That's overly restrictive.

Not to mention, we've already discussed fixing current features so that they 
stop disallowing certain idioms. For instance, in order to make it so that 
caching and lazy loading and whatnot are not disallowed in classes due to 
issues with const, we've talked about removing toString, opEquals, toHash, and 
opCmp from Object. Then the programmer can decide whether they want to use 
const or not and we'd no longer be disallowing the idioms that are prevented 
by forcing const on Object.

You're basically suggesting that we disallow any idiom which requires that 
structs be deep copied, and I think that that's bad policy. It's one thing to 
encourage programmers to not write such structs and to use other idioms like 
COW or reference counting. It's another thing entirely to disallow them. It's 
one of C++'s prime tenets to try and not force the programmer to program in a 
certain way or in a certain paradigm, and I think that D should do the same. 
If we want to encourage certain idioms and discourage others, fine. But 
outright disallowing them is a bad idea IMHO.

- Jonathan M Davis