A Possible Vision for Macros in Swift

Evolution Pitches
94

I'd be interested in seeing more information provided in the MacroExpansionContext. When implementing a delegate method, I frequently find myself doing this:

func delegator(_ delegator: Delegator, willBegin operation: SomeOperation) {
    print(#function, delegator, operation)
}

func delegator(_ delegator: Delegator, didFinish operation: SomeOperation) {
    print(#function, delegator, operation)
}

This is a quick way for me to try out a new piece of code and quickly get a sense of the control flow between the delegator and the delegate. I was thinking that this would potentially be a nice macro:

func delegator(_ delegator: Delegator, willBegin operation: SomeOperation) {
    #printArguments
}

However, when I looked at the MacroExpansionContext, I didn't see a way I could implement this. Is there a way to get the containing scope and, if it's an argument-taking thing, get the list of arguments so I can splat out a print(...) call?

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