Improve getting & setting data on spans and transactions

[giortzisg]

Problem Statement

Currently, if I want to get attribute data from an existing span or transaction I need to check the existance and also typecast into the final value.

if d, found := transaction.Data["dataAttr1"]; found {
  if dataAttr1, ok := d.(int); ok {
    transaction.SetData("dataAttr1", dataAttr1.(int)+42)
  }
}

For getting multiple values, the code footprint would become fairly large. It would be nicer to be able to handle getting and casting values with a GetData function in the transaction/span layer.

Solution Brainstorm

Not sure about the better way of doing that, but here are two proposals.

• Generic helper function:

// signature
func GetData[T any](s *Span, name string) (T, error)

// usage 
val, err := sentry.GetData[int](transaction, "int")
if err != nil {
// handle error
}
transaction.SetData("int", val+42)

pros: small footprint, less maintenance, custom data structures
cons: casting on runtime (not type safe), how to handle complex cases?

• Custom datastructure and types
  not sure on exact implementation but something like otel Value type?

type Value struct {
	vtype    Type
	numeric  uint64
	stringly string
	slice    interface{}
}

pros: concrete data types (no interface{}), type safe
cons: bigger footprint, complex logic, more maintenance, no support for custom data types