On Tue, 2020-04-21 at 18:09 +0000, tsbockman via Digitalmars-d-learn wrote: > On Tuesday, 21 April 2020 at 16:03:20 UTC, Russel Winder wrote: > > then which of these is the right way of accessing the value? > > > > cast(ubyte)ZoneNumber.One > > to!ubyte(ZoneNumber.One) > > Either is acceptable because there is no way that this operation > can fail. Using a naked `cast` makes less work for the compiler > and performs optimally with or without inlining, though.
Seems like in this case cast is better than to! use. > > conversely what is the right way of going the other way: > > > > cast(ZoneNumber)1 > > to!ZoneNumber(1) > > Use `to` except where you can gaurantee that the input value maps > to a valid enum member, because `cast` does not check your work: > > writeln(cast(ZoneNumber)17); // breaks the type system > writeln(to!ZoneNumber(17)); // throws a ConvException: Value > (17) does not match any member value of enum 'ZoneNumber' > > So, `cast` is faster, but unsafe. `to` is slower, but protects > the enum's invariant. Thanks. It seems to! is de rigueur in this case. -- Russel. =========================================== Dr Russel Winder t: +44 20 7585 2200 41 Buckmaster Road m: +44 7770 465 077 London SW11 1EN, UK w: www.russel.org.uk
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