i1494 passing opts to attributevalue marshalling

[radutopala]

Fixes #1494

[jasdel]

Thanks for taking the time to create this PR @radutopala. Modifing the signatures of the Marshal methods would be a breaking change, and we could not release it.

Alternatively new Marshal methods could be defined with different names, e.g. MarshalWithOptions to take the functional options.

Also we'd probably want similar new functions for the Unmarshal set of functions.

[radutopala]

Adding optFns ...func(*EncoderOptions) as a variadic arg means no breaking changes, one can call Marshall with or without passing any optFns. But if I'm missing something, please let me know.

[jasdel]

Thanks for the feedback. Adding a variadic arg to a function call will not break existing callers, but since in Go functions can be types and variables, any application that creates a variable or struct member type matching the Marshal function signature would break if variadic arg were added. This is the reasoning behind suggesting this behavior would need to be new functions.

https://go.dev/play/p/c4yT8-DsHo9

[radutopala]

@jasdel it's an extreme edge case, wondering who'd use this pattern with this specific func. But ok, better safe! I'll push some changes.

[radutopala]

@jasdel branch updated, please CR / provide next steps.

[jasdel]

Thanks for taking the time to put this PR together, and make the requested updates. I've added changelog notes to the PR. We'll get this update merged in and released in the SDK's next update.