Swift 重载 NSDecimalNumber 运算符

Question

I'm wondering if there is a reason Swift doesn't just overload the standard arithmetic (+,-,*,<,> etc.) operators for NSDecimalNumber , and instead opts for traditional methods with names like adding , subtracting etc.

I'd like to overload these operators, is this a good idea, what are the potential drawbacks?

EDIT

Apparently Swift 3 added a Decimal type. Swift 3 also dropped NS in front of a bunch of other types so I assumed Decimal was just an NSDecimal with the NS dropped, but this is not the case, Although it doesn't really answer the question, I think using Decimal instead of NSDecimalNumber should usually be a good response going forward for Swift 3 and later. One reason you may want to stick with NSDecimalNumber is if you have many extensions and don't want to bridge every time you want to use extension methods.

Answer 1

Have you though about using Decimal instead of NSDecimalNumber ?

let d1 = Decimal(integerLiteral: 10)
let d2 = Decimal(integerLiteral: 2)
let result = d1 * d2 // 20

Answer 2

I have to retain the old NSDecimalValue to use with Core Data. I wanted to be able to use comparisons, so I added this extension:

extension NSDecimalNumber: Comparable { // Comparable adds <=, >=, and > 

  public static func ==(lhs: NSDecimalNumber, rhs: NSDecimalNumber) -> Bool {
    return lhs.compare(rhs) == .orderedSame
  }

  public static func <(lhs: NSDecimalNumber, rhs: NSDecimalNumber) -> Bool {
    return lhs.compare(rhs) == .orderedAscending
  }

}