[Issue 5467] library-based typedef
https://issues.dlang.org/show_bug.cgi?id=5467 Basile-z changed: What|Removed |Added CC|b2.t...@gmx.com | --
[Issue 5467] library-based typedef
https://issues.dlang.org/show_bug.cgi?id=5467 b2.t...@gmx.com changed: What|Removed |Added Status|NEW |RESOLVED CC||b2.t...@gmx.com Resolution|--- |FIXED --- Comment #5 from b2.t...@gmx.com --- this should have been closed for a while (std.typecons.TypeDef) --
[Issue 5467] library-based typedef
https://issues.dlang.org/show_bug.cgi?id=5467 Andrei Alexandrescu changed: What|Removed |Added Version|D1 & D2 |D2 --
[Issue 5467] library-based typedef
http://d.puremagic.com/issues/show_bug.cgi?id=5467 Robert Clipsham changed: What|Removed |Added CC||rob...@octarineparrot.com --- Comment #4 from Robert Clipsham 2012-01-02 00:15:40 GMT --- (In reply to comment #0) > 1. Something that's just like another type yet "parallel" with it. This is > good > for abstractions that encode different units of measurement that aren't > supposed to be mixed. > > ParallelTypedef!double Miles; > > Such a type should accept explicit initialization from a regular double: > > auto dist = Miles(3.2); > > However it shouldn't accept initialization from another parallel typedef: > > ParallelTypedef!double Kms; > auto dist1 = Kms(4); > auto dist2 = Miles(dist1); // no This needs a better name, parallel is transitive, so Miles(dist1) should work (if there are 3 things, A, B and C, A is parallel to B and B is parallel to C, then A is parallel to C). -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email --- You are receiving this mail because: ---
[Issue 5467] library-based typedef
http://d.puremagic.com/issues/show_bug.cgi?id=5467 Stewart Gordon changed: What|Removed |Added CC||s...@iname.com --- Comment #3 from Stewart Gordon 2012-01-01 13:50:10 PST --- (In reply to comment #0) > ParallelTypdef!(double, "allow_arithmetic", "allow_mixed:*,/,%") > Miles; This leaves much to be desired: we want to allow Miles * double but not Miles * Miles, and Miles + Miles but not Miles + double. Moreover, Miles / Miles wants to return double. Maybe we need a more specialised version of ParallelTypedef that does primitive units checking. opMul and opDiv would themselves be templates therein. Maybe I'll have a go at implementing something when I have a bit more time > 2. Opaque "handle" types that can be used with overloading. The base type of > the typedef is just the storage strategy: So it's basically a struct wrapper. > 3. Proper subtype. Create a true subtype of a type that allows explicit > initialization from the type and implicit conversion to the type. This seems the closest to how typedefs behave at the moment. > 4. Proper supertype. The base type implicitly converts to the introduced type, > but not vice versa. Makes sense, but I'm not sure what practical it would have -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email --- You are receiving this mail because: ---
[Issue 5467] library-based typedef
http://d.puremagic.com/issues/show_bug.cgi?id=5467 Jonathan M Davis changed: What|Removed |Added CC||jmdavisp...@gmx.com --- Comment #2 from Jonathan M Davis 2011-12-30 03:23:17 PST --- https://github.com/D-Programming-Language/phobos/pull/300 -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email --- You are receiving this mail because: ---
[Issue 5467] library-based typedef
http://d.puremagic.com/issues/show_bug.cgi?id=5467
--- Comment #1 from Trass3r 2011-01-20 08:51:08 PST ---
And that's the latest code draft I could find:
enum Type
{
Independent,
Super,
Sub,
Parallel,
}
struct Typedef( T, Type type = Type.Sub, T init = T.init, string _f = __FILE__,
int _l = __LINE__ )
{
T payload = init;
static if ( type != Type.Independent )
{
this( T value )
{
payload = value;
}
}
static if ( type == Type.Sub)
{
// typedef int foo; foo f;
// f.opCast!(t)() == cast(t) f
T opCast(T)()
{
return payload;
}
}
static if ( type == Type.Sub || type == Type.Parallel )
{
alias payload this;
}
static if ( type == Type.Super )
{
typeof( this ) opAssign( T value )
{
payload = value;
return this;
}
}
else static if ( type == Type.Sub )
{
@disable void opAssign( T value );
}
}
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