digitalmars.D.learn - Tuple/Typedef question
- Martin (15/15) Jan 11 2015 Is there a way to get Tuple (and Typedef) from the std.typecons
- ketmar via Digitalmars-d-learn (13/35) Jan 11 2015 On Sun, 11 Jan 2015 11:41:08 +0000
- Martin (3/41) Jan 11 2015 I can't believe I missed the cookie part. Thanks!
- ketmar via Digitalmars-d-learn (7/26) Jan 11 2015 On Sun, 11 Jan 2015 12:00:19 +0000
- Dicebot (32/32) Jan 11 2015 I use this Typedef implementation instead:
Is there a way to get Tuple (and Typedef) from the std.typecons module to generate a new type that is unique on every instantiation? What I mean is: alias T1 = Tuple!(int, int); alias T2 = Tuple!(int, int); writeln(__traits(isSame, T1, T2)); // prints true When using Typedef, the types are still the same: alias T1New = Typedef!(T1); alias T2New = Typedef!(T2); writeln(__traits(isSame, T1New, T2New)); // still prints true The documentation of Typedef says: "Typedef allows the creation of a unique type which is based on an existing type. Unlike the alias feature, Typedef ensures the two types are not considered as equals." Shouldn't the second part at least print false then?
Jan 11 2015
On Sun, 11 Jan 2015 11:41:08 +0000 Martin via Digitalmars-d-learn <digitalmars-d-learn puremagic.com> wrote:Is there a way to get Tuple (and Typedef) from the std.typecons module to generate a new type that is unique on every instantiation? What I mean is: =20 alias T1 =3D Tuple!(int, int); alias T2 =3D Tuple!(int, int); =20 writeln(__traits(isSame, T1, T2)); // prints true =20 When using Typedef, the types are still the same: =20 alias T1New =3D Typedef!(T1); alias T2New =3D Typedef!(T2); =20 writeln(__traits(isSame, T1New, T2New)); // still prints true =20 The documentation of Typedef says: "Typedef allows the creation of a unique type which is based on an existing type. Unlike the alias feature, Typedef ensures the two types are not considered as equals." =20 Shouldn't the second part at least print false then?as for `Typedef!` -- you can use it's third arg, "cookie": import std.typecons; alias T1 =3D Tuple!(int, int); alias T2 =3D Tuple!(int, int); alias T1New =3D Typedef!(T1, T1.init, "t0"); alias T2New =3D Typedef!(T2, T2.init, "t1"); pragma(msg, __traits(isSame, T1New, T2New)); // false there was a heated discussion about `std.typecons.Typedef`, built-in `typedef` and other related things, but the decision was to keep the status quo.
Jan 11 2015
On Sunday, 11 January 2015 at 11:52:42 UTC, ketmar via Digitalmars-d-learn wrote:On Sun, 11 Jan 2015 11:41:08 +0000 Martin via Digitalmars-d-learn <digitalmars-d-learn puremagic.com> wrote:I can't believe I missed the cookie part. Thanks!Is there a way to get Tuple (and Typedef) from the std.typecons module to generate a new type that is unique on every instantiation? What I mean is: alias T1 = Tuple!(int, int); alias T2 = Tuple!(int, int); writeln(__traits(isSame, T1, T2)); // prints true When using Typedef, the types are still the same: alias T1New = Typedef!(T1); alias T2New = Typedef!(T2); writeln(__traits(isSame, T1New, T2New)); // still prints true The documentation of Typedef says: "Typedef allows the creation of a unique type which is based on an existing type. Unlike the alias feature, Typedef ensures the two types are not considered as equals." Shouldn't the second part at least print false then?as for `Typedef!` -- you can use it's third arg, "cookie": import std.typecons; alias T1 = Tuple!(int, int); alias T2 = Tuple!(int, int); alias T1New = Typedef!(T1, T1.init, "t0"); alias T2New = Typedef!(T2, T2.init, "t1"); pragma(msg, __traits(isSame, T1New, T2New)); // false there was a heated discussion about `std.typecons.Typedef`, built-in `typedef` and other related things, but the decision was to keep the status quo.
Jan 11 2015
On Sun, 11 Jan 2015 12:00:19 +0000 Martin via Digitalmars-d-learn <digitalmars-d-learn puremagic.com> wrote:this part deserves a better explanation in docs, 'cause it's easy to miss the details, especially for those who assumed that each `Typedef!` creates a distinct type. too bad that my writing skills sux (and i'm really biased against the current `Typedef!`).as for `Typedef!` -- you can use it's third arg, "cookie": import std.typecons; alias T1 =3D Tuple!(int, int); alias T2 =3D Tuple!(int, int); alias T1New =3D Typedef!(T1, T1.init, "t0"); alias T2New =3D Typedef!(T2, T2.init, "t1"); pragma(msg, __traits(isSame, T1New, T2New)); // false there was a heated discussion about `std.typecons.Typedef`,=20 built-in `typedef` and other related things, but the decision was to=20 keep the status quo.=20 I can't believe I missed the cookie part. Thanks!
Jan 11 2015
I use this Typedef implementation instead: /// one with non-default initializer template Typedef(T, istring name, T initval) { static assert (name.length, "Can't create Typedef with an empty identifier"); enum Typedef = ("struct " ~ name ~ "{ " ~ T.stringof ~ " value = " ~ initval.stringof ~ ";" ~ "alias value this;" ~ " }"); } /// basic overload template Typedef(T, istring name) { static assert (name.length, "Can't create Typedef with an empty identifier"); enum Typedef = ("struct " ~ name ~ "{ " ~ T.stringof ~ " value; " ~ "alias value this;" ~ " }"); } unittest { mixin(Typedef!(int, "MyInt1")); mixin(Typedef!(int, "MyInt2")); static assert (!is(MyInt1 : MyInt2)); }
Jan 11 2015