On Sunday, 27 July 2014 at 00:43:40 UTC, H. S. Teoh via
Digitalmars-d-learn wrote:
On Sat, Jul 26, 2014 at 05:14:44PM +0000, via
Digitalmars-d-learn wrote:
Hmmm... thinking about it, is this possible?
1. Remove the constraints to match anything.
2. Inside the template, have some construct that enumerates
all possible
overloads and UFCS functions that are visible at the point of
instantiation.
3. If this set contains only the current template, use a
static assert
to print the message.
4. Otherwise, make the template fail to compile somehow (for
example,
evaluate a semantically invalid expression), and hope that the
compiler will then take the other overloads into consideration
(SFINAE).
Could this work?
D does not have SFINAE.
http://dlang.org/templates-revisited.html says otherwise.
But thinking about it, I've never seen it used anywhere, nor used
it myself, and even the examples in the linked article under the
SFINAE section use `is` expressions instead...
This has been discussed before. I proposed the following
solution:
- Sig constraints should match all types that the function
*logically*
accepts -- even if the current implementation does not
support some of
said types.
- In the function body, use a `static if` chain to implement
specializations.
- In the final else clause, do a static assert(0) with a
user-friendly
error message.
But this prevents other people from providing overloads in their
own modules :-(
