Re: __traits isCopyable vs isPOD
On Tuesday, 29 November 2022 at 00:50:54 UTC, Paul Backus wrote: If your goal is to avoid calling the copy constructor (and, I assume, to avoid unnecessary instantiations of `move`), then yeah, `isPOD` is the one you want. Thanks.
Re: __traits isCopyable vs isPOD
On Monday, 28 November 2022 at 23:11:37 UTC, Per Nordlöw wrote: the real question I had is whether one should use `isPOD` instead of `isCopyable` in cases ```d static if (__traits(isCopyable, Element)) insertAt(element, index); else insertAt(move(element), index); ``` because that avoids any potential call to the copy-constructor and destructor of `Element`. Afaict, one should. If your goal is to avoid calling the copy constructor (and, I assume, to avoid unnecessary instantiations of `move`), then yeah, `isPOD` is the one you want.
Re: __traits isCopyable vs isPOD
On Monday, 28 November 2022 at 22:59:13 UTC, Paul Backus wrote: Lots of types. For example, types with copy constructors or destructors are not POD but may still be copyable. This should be obvious if you read the definition of POD linked from the language spec: https://dlang.org/glossary.html#pod I guess I knew that, sorry for the dumb question - the real question I had is whether one should use `isPOD` instead of `isCopyable` in cases ```d static if (__traits(isCopyable, Element)) insertAt(element, index); else insertAt(move(element), index); ``` because that avoids any potential call to the copy-constructor and destructor of `Element`. Afaict, one should.
Re: __traits isCopyable vs isPOD
On Monday, 28 November 2022 at 20:58:43 UTC, Per Nordlöw wrote: For which types `T` does ```d __traits(isCopyable, T) ``` differ from ```d __traits(isPOD, T) ``` ? Lots of types. For example, types with copy constructors or destructors are not POD but may still be copyable. This should be obvious if you read the definition of POD linked from the language spec: https://dlang.org/glossary.html#pod
Re: __traits isCopyable vs isPOD
On Monday, 28 November 2022 at 20:58:43 UTC, Per Nordlöw wrote: For which types `T` does ```d __traits(isCopyable, T) ``` differ from ```d __traits(isPOD, T) ``` ? I'm asking because I have code like ```d static if (__traits(isCopyable, Element)) insertAt(element, index); else insertAt(move(element), index); ``` and I wonder if one in those cases should be using `isCopyable` or `isPOD`.
