On Friday, 14 July 2017 at 22:49:18 UTC, data pulverizer wrote:
On Friday, 14 July 2017 at 22:25:15 UTC, data pulverizer wrote:
I am aware that this suggestion touches the language and the
compiler - and may significant implications. I would like to
know whether this could be done without too much effort and
whether it would break anything else?
If you are writing lots of overloaded templates, constraints
can have unintended behaviour because you end up telling the
compiler what not to do rather than what to do. The above
Unions are clear and simple, easy to use and should result in
cleaner more robust code.
In addition with template specializations you get constraints
for free. If I implement template overloads which are all
specializations, the compiler gives me a very informative error
if I step outside the pre-defined set of implementations.
That's just brilliant - exactly what you want! I immediately
know when I see that error what the issue is. Am I being naive?
Why are constraints better?
One important characteristic about constraints, is that they are
not bound to types.
Also they can from conjunctions and disjunctions.
Combined with ctfe they are very flexible and powerful.
I do not know how you would do the same with specializations.
Then again being unfamiliar with template-specializations I might
be overlooking something.
