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Re: [SG20] Difficulties in teaching the use of C++20 concepts

From: Nevin Liber <nevin_at_[hidden]>
Date: Sun, 22 Dec 2019 13:41:58 -0600
On Sun, Dec 22, 2019 at 11:48 AM Jon Kalb via SG20 <sg20_at_[hidden]>

> There are two cases, what Herb calls “tracking” and “making the type
> stick.” I think I’d call them “tracking” and “fixing.” I think they should
> be spelled:
> auto x{expr}; // tracking - we want *x* to be whatever *expr returns*,
> even if it is changed by maintenance

The callee decides the type.

> auto x{type{expr}}; // fixing - we want *x* to be *type* regardless of
> what expr returns.

The caller decides the type.

I don’t see any other case.

The case that isn't here is the no surprises case when you want the caller
type and the callee type to match an explicitly mentioned type.
 Nevin ":-)" Liber  <mailto:nevin_at_[hidden] <nevin_at_[hidden]>>

Received on 2019-12-22 13:45:03