https://issues.dlang.org/show_bug.cgi?id=14477
--- Comment #3 from MichaelZ <[email protected]> --- This is currently an issue for us, and it has been proposed we use Algebraic!Foo instead, which appears to work sufficiently, see below. What aspects are against doing it this way? The implementation of Algebraic "looks" a lot more heavyweight, but is it really, particularly in this very specific usage? If we don't like the toString behaviour, or want to have .nullify, and prefer .isNull to .hasValue, we can always make Nullable a pretty minimal wrapper... Thoughts? ----- import std.variant; import std.stdio; import std.string; struct Foo { int x; @disable this(); this(int value) { x=value; } } void main() { Algebraic!Foo foo; writeln("hasValue for default-initialized foo: %s".format(foo.hasValue)); writeln("Format default-initialized foo: %s".format(foo)); foo = Foo(5); writeln("hasValue for set foo: %s".format(foo.hasValue)); writeln("Format set foo: %s".format(foo)); foo = Algebraic!Foo(); // Nullable's foo.nullify is cooler :/ writeln("hasValue for reset foo: %s".format(foo.hasValue)); writeln("Format reset foo: %s".format(foo)); } --- output --- hasValue for unset foo: false Format unset foo: <Uninitialized VariantN> hasValue for set foo: true Format set foo: Foo(5) hasValue for unset foo: false Format unset foo: <Uninitialized VariantN> --
