> var depositPromille: Decimal(10,3) = -1234.56
> typealias Money = Decimal(20,2)
There is no mechanism to parameterize types like this. (Specifically, you can
only parameterize a generic type with types, not integers or other values.)
That makes this a fairly large effort—certainly not impossible, but more than
just writing some code and putting it in the standard library. "As soon as
possible" will still be quite a ways away, and may not even come in this Swift
version.
As a stopgap, use NSDecimal (which is not fixed, but does provide decimal
arithmetic) or write your own Money struct:
struct Money {
private var cents: Int
init(_ value: Int) {
cents = value * 100
}
init(cents: Int) {
self.cents = cents
}
init(approximating value: Double) {
cents = Int(value * 100)
}
}
extension Int {
init(approximating value: Money) {
self = value.cents / 100
}
init(cents value: Money) {
self = value.cents
}
}
extension Double {
init(approximating value: Money) {
self = Double(value.cents) / 100
}
}
extension Money: StringLiteralConvertible {
// or FloatLiteralConvertible if you think you can get away
with it
...
}
extension Money: Hashable, Comparable, CustomStringConvertible {
...
}
func + (lhs: Money, rhs: Money) -> Money { return Money(cents:
lhs.cents + rhs.cents) }
func * (lhs: Money, rhs: Int) -> Money { return Money(cents: lhs.cents
* rhs) }
// etc.
--
Brent Royal-Gordon
Architechies
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