On 26-Sep-12 21:39, Denis Shelomovskij wrote:
25.09.2012 21:14, Denis Shelomovskij пишет:
.NET has FlagsAttribute, Java has EnumSet. Looks like we need this too.
How about to add a library solution to Phobos?
My variant is here (search for `flagEnum`):
https://bitbucket.org/denis_sh/misc/src/tip/stdd/typecons.d
It has a bug and I have no idea how to fix it:
`AB.init |= AB.a` and `AB.a |= AB.a` are allowed.
(no, we can't make `AB.a` const to disallow the second case because it
will disallow this: `auto a = AB.a; a |= AB.a;`)
Also I'm not sure:
* Should we support converting from a number to a flag enum?
I'd suggest an explicit way to do so. Like to!(flagEnum) or a standalone
helpers.
* If so, should we support values not from enum flags or throw
exceptions (it may be configurable)?
If to! is used I guess throw exceptions if it doesn't fit.
* Is `flagEnum` an appropriate name?
Since it's a type (right?) I'd think EnumFlag, FlagSet or even Java's
EnumSet. Generally I think I like words 'set' and/or 'flag' in the name.
OK. Looks like such functionality isn't needed and I don't have to do a
pull request. What about to close
http://d.puremagic.com/issues/show_bug.cgi?id=6946
with WONTFIX?
First, calm down. Second, I, for one, like it.
The place to go is most likely std.bitmanip or std.typecons. I haven't
looked much at the actual code but the usage seems straightforward.
Another thought is to generalize it to something beyond 1-bit flags. How
about packing various flags (set of 3-state flag, 4-state flag etc.) in
one fixed struct?
--
Dmitry Olshansky
