Function pickAmong
Wrap one of two values in a SuperStruct that encompasses both types.
This can be used to return a value from one of several different types.
Similar to std.range.chooseAmong, but for a broader range of types.
Prototype
auto pickAmong(T...)(
size_t index,
T values
);
Parameters
| Name | Description |
|---|---|
| index | which value to choose, must be less than the number of values |
| values | two or more values to pick from |
Returns
A SuperStruct!T wrapping the argument at index.
Example
use pickAmong to form a common return type from different structs
struct Zero { auto num = 0; }
struct One { auto num = 1; }
struct Two { auto num = 2; }
auto val = pickAmong(0, Zero(), One(), Two());
assert(val.num == 0);
val = pickAmong(1, Zero(), One(), Two());
assert(val.num == 1);
val = pickAmong(2, Zero(), One(), Two());
assert(val.num == 2);
Example
pickAmong is similar to std.range.chooseAmong:
import std.range : only, iota, repeat;
import std.algorithm : equal;
auto r = pickAmong(0, only(1), iota(0,3), repeat(1,3));
assert(r.equal([1]));
r = pickAmong(1, only(1), iota(0,3), repeat(1,3));
assert(r.equal([0,1,2]));
r = pickAmong(2, only(1), iota(0,3), repeat(1,3));
assert(r.equal([1,1,1]));
Authors
Ryan Roden-Corrent (rcorre)
Copyright
© 2015, Ryan Roden-Corrent
License
MIT