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Alias std.variant.Variant

Alias for VariantN instantiated with the largest size of creal, char[], and void delegate(). This ensures that Variant is large enough to hold all of D's predefined types unboxed, including all numeric types, pointers, delegates, and class references. You may want to use VariantN directly with a different maximum size either for storing larger types unboxed, or for saving memory.

alias Variant = VariantN!(32L);


Variant a; // Must assign before use, otherwise exception ensues
// Initialize with an integer; make the type int
Variant b = 42;
writeln(b.type); // typeid (int)
// Peek at the value
assert(b.peek!(int) !is null && *b.peek!(int) == 42);
// Automatically convert per language rules
auto x = b.get!(real);

// Assign any other type, including other variants
a = b;
a = 3.14;
writeln(a.type); // typeid (double)
// Implicit conversions work just as with built-in types
assert(a < b);
// Check for convertibility
assert(!a.convertsTo!(int)); // double not convertible to int
// Strings and all other arrays are supported
a = "now I'm a string";
writeln(a); // "now I'm a string"


can also assign arrays

Variant a = new int[42];
writeln(a.length); // 42
a[5] = 7;
writeln(a[5]); // 7


Can also assign class values

Variant a;

class Foo {}
auto foo = new Foo;
a = foo;
assert(*a.peek!(Foo) == foo); // and full type information is preserved


Andrei Alexandrescu


Boost License 1.0.