If you are willing to include some global state to your package, you could always have memoizing logic occur outside of the Number type. That is - you could still have every Number be passed around by value, but for calculating sqrt you'd check some threadsafe global state and either return a pre-calculated value or calculate+cache it.
The obvious downside is that cleaning up this pre-calculation is tricky. A naive implementation would cause all sqrts to be cached for the rest of the program execution. A more complex one would involve some sort of expiration. On Monday, March 27, 2023 at 9:15:01 AM UTC-6 Travis Keep wrote: > I have this package: https://pkg.go.dev/github.com/keep94/sqroot, which > computes square roots to arbitrary precision. The Number type is a value > type that represents a square root value. Early on it made sense to make > Number be an immutable value type because it represents an immutable value > such as sqrt(5). > > However, now I want to add memoization to square root values. I have done > this in a private branch, by adding a WithMemoize() method to Number that > returns a new Number with memoization turned on. I have made the > memoization multiple goroutine safe so that Number types still appear as > immutable numerical values. > > However, I am not sure that memoization works well with Value type > semantics. For instance, if I have two Numbers, x and y, and I set y = x > and continue to use x, y will see any future memoization done for x because > I implement memoization with pointers behind the scenes. But, y = x > implies that y gets a snapshot of x and won't see future changes in x. > Moreover, I will never be able to add a method to Number that returns > information about memoization progress because that would break > immutability of the Number value type. > > To solve this dilemma, I could change the API to be pointer based, by > accepting and returning *Number instead of Number. Then I could say that > Number does not support assignment directly. The advantage of using *Number > is that if x and y are *Number and I set y = x, it is clear that whatever > happens to x will happen to y because they point to the same instance. > However, that would be a huge breaking change. > > Any suggestions on what to do? > -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/golang-nuts/ecee6bc5-7fb7-4380-8930-1479d47a962bn%40googlegroups.com.
