Support disabling run following for workflow results

[cretz]

What was changed

• Add WorkflowRun.GetWithOptions that supports an option to disable following runs
• Return continue as new error if follow runs disabled for continue as new

Why?

Currently we always follow to the last run in the "chain". Some people don't want this, especially for crno (see #789).

Checklist

1. Closes Allow getting workflow result to not follow runs #789

[cretz]

Should I fail if this was set to true but a run ID was not provided? Is there a use case for not providing a run ID but still not following to the next run?

[bergundy]

We don't in TS. I can't think of a reason not to allow it, saves looking up the last run ID for a workflow ID.

[bergundy]

Can we change this setting name to FollowRuns and still default to true? It's easier to follow.

[cretz]

Can we change this setting name to FollowRuns and still default to true? It's easier to follow.

I am afraid not in Go. You can't default fields, their default is always the zero value which for booleans is false. This is why for all Go structs, you specifically build the field where false is the reasonable default.

[bergundy]

Yeah, I get it. I thought that we could check if the options struct is null and default to true but we want empty struct to also default to true.

[cretz]

This options struct is never null inside the outer options (it's not a pointer). And even if it could be nullable, we want to support people creating it and just setting the fields they care about instead of trying to differentiate between unset and explicit false.

[bergundy]

Cool, I agree this is the best approach

[bergundy]

Took a brief look and left a comment inline for your consideration.