On 03/06/2014 12:35 AM, bearophile wrote:
Andrei Alexandrescu:
Walter and I would preapprove implementation of static foreach if and
only if a solid DIP comes about.
Some suggestions for a static foreach DIP:
- It should work at global scope too (I'd like with() to work at global
scope too).
Of course. static foreach will be both a declaration and a statement.
- The semantics of "static foreach (x; TypeTuple!(1, 2))" should not
change, if possible (in alternative it could change a little, but
eventually become a syntax error).
No. static foreach does not introduce a new scope. "TypeTuple"-foreach
does. Deprecating this language feature is not in scope of the 'static
foreach' DIP. It's separate, and I'd even argue for not doing it.
- At first "foreach (x; TypeTuple!(1, 2))" should give a warning, then
a deprecation message, and then an error message that "static" is
required. This makes iteration on type tuples visibly static.
It's not the same thing.
- "static foreach_reverse (immutable i; 0 .. 10)" could be supported.
Good point.
- "static foreach (immutable i; iota(1, 10, 2))" should work.
- Please no tuple unpacking, because this foreach feature should die and
be replaced by something more general and more correct.
...
foreach and static foreach should behave the same in all shared aspects.
(Unfortunately, this statement is somewhat messy to formalize.)
