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April 06, 2014 [Issue 12530] New: uniform initialization for type tuples too | ||||
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https://d.puremagic.com/issues/show_bug.cgi?id=12530 Summary: uniform initialization for type tuples too Product: D Version: D2 Platform: All OS/Version: All Status: NEW Severity: enhancement Priority: P2 Component: DMD AssignedTo: nobody@puremagic.com ReportedBy: monarchdodra@gmail.com --- Comment #0 from monarchdodra@gmail.com 2014-04-06 12:14:28 PDT --- Not sure if enhancement request or bug, but filing as EH. I think these should work: //---- auto a = TypeTuple!(int, int, int)(); //(0, 0, 0) auto b = TypeTuple!(int, int, int)(1); //(1, 1, 1) //auto c = TypeTuple!(int, int, int)(1, 2); //Should fail auto d = TypeTuple!(int, int, int)(1, 2, 3); //(1, 2, 3) //---- Currently they all produce: Error: function expected before (), not (int, int, int) of type (int, int, int) In particular, I think this should work: //---- TypeTuple!(int, int, int) a = ...; TypeTuple!(int, int, int) b = TypeTuple!(int, int, int)(a); //---- Though arguably, it's the exactly the same as the "d" case above. -- Configure issuemail: https://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- |
April 06, 2014 [Issue 12530] uniform initialization for type tuples too | ||||
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Posted in reply to monarchdodra@gmail.com | https://d.puremagic.com/issues/show_bug.cgi?id=12530 bearophile_hugs@eml.cc changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |bearophile_hugs@eml.cc --- Comment #1 from bearophile_hugs@eml.cc 2014-04-06 12:32:55 PDT --- (In reply to comment #0) > I think these should work: > > auto a = TypeTuple!(int, int, int)(); //(0, 0, 0) > auto b = TypeTuple!(int, int, int)(1); //(1, 1, 1) > //auto c = TypeTuple!(int, int, int)(1, 2); //Should fail > auto d = TypeTuple!(int, int, int)(1, 2, 3); //(1, 2, 3) Please show one or more use cases. -- Configure issuemail: https://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- |
April 06, 2014 [Issue 12530] uniform initialization for type tuples too | ||||
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Posted in reply to monarchdodra@gmail.com | https://d.puremagic.com/issues/show_bug.cgi?id=12530 --- Comment #2 from monarchdodra@gmail.com 2014-04-06 13:02:13 PDT --- (In reply to comment #1) > Please show one or more use cases. I've had need of this, for example, to transform the types of variadic arguments, before passing them to another function. "reduce" or "uninitializedArray" come to mind: //---- void main() { uninitialized!(int[][])(1, 2); } alias ToSizeT(T) = size_t; enum IsSizeT(T) = is(S == size_t); auto uninitialized(T, Args...)(Args args) { //transform the "int" inference to "size_t" alias SizeTArgs = staticMap!(ToSizeT, Args); //Call with the same arguments, but cast to size_t... //if the cast is implicitly safe return impl!T(SizeTArgs(args)); } auto impl(T, Args...)(Args args) //Avoid bloat by requesting size_t args. { static assert(allSatisfy!(IsSizeT, Args)); } //---- The same design can be used to transform/forward args, say to unqualify all of them at once: //---- void myFun(Args(Args args)) { alias UArgs = staticMap!(Unqual, Args); static if (!is(UArgs == ARgs)) myFun(UArgs(args)); else { //actual implementation here } } Or, in the case of reduce, to build the different seeds from front: auto result = tuple(SeedTypes(r.front)); -- Configure issuemail: https://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- |
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