Decimal32, Decimal64, and Decimal128 Design Approach

[xwu (Xiaodi Wu)]

@mgriebling

  public init(stringLiteral value: StringLiteralType, rounding rule: Rounding)

init(stringLiteral:) is an initializer magically called when a type conforming to ExpressibleByStringLiteral is initialized from a string literal; it is not meant to be called directly.

An API with an additional argument as here would never be called magically, and by analogy should never be called directly, so...

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@mgriebling

public func adding(to other: Self, rounding rule: Rounding) -> Self 

The convention is that to isn't used for adding.

@mgriebling

  public func multiplying(by other: Self, rounding rule: Rounding) -> Self 
  public func dividing(by other: Self, rounding rule: Rounding) -> Self

The convention is multiplied(by:) and divided(by:).

@mgriebling

Not sure if there should be both mutating and non-mutating operations.

Yes.

@mgriebling

There also seem to be inconsistencies in how the ed is used. There is a rounded() method that returns a value while addingProduct(::) returns a value.

Either "-ed" or "-ing" is used to indicate a non-mutating operation; which one is used depends on English grammar. Prefer "-ed" if both work. If neither work, the fallback is the "form" convention that no one likes. In this case, no innovation is required as all of the APIs have been settled previously (see SE-0067).

[mgriebling (Mike Griebling)]

Thanks @xwu for the insight. I'll remove this from the public interface.