On 7/21/14 2:22 PM, Tobias Müller wrote:
We discussed this with Bartosz literally for weeks (him being a fan of
auto_ptr for too long, later completely converted against it and I take
credit for that :o)). With auto_ptr this was possible:
auto_ptr<int> a(new int);
auto_ptr<int> b = a;
It would nullify a with copy syntax. That code won't compile with
unique_ptr; you'd need an explicit move(a).
It only got worse from there: passing into functions, member variables...
MOVING WITH COPY SYNTAX DOES NOT WORK.
It's cut and dried.
... in C++. Not in Rust. That's because, unlike C++, Rust is designed
from the ground up to support moves and copies in a first class way.
It's just strange that you can change the semantic of an already existing
operation just by adding new capabilities. Adding traits should define new
operations with new semantics, not changing the semantics of existing
operations. At least that's how it works for all other traits, and
deviating from that is at least surprising.
Hence the Opt-In Built-In Traits proposal
Maybe the syntax was just too heavy?
Any syntax at all is too much. I am convinced of that.
Patrick
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