WIP: Propose new Replace() function for list flags.

[therealmitchconnors]

This PR addresses the lack of a concrete way to replace, rather than append to, Slice and Array flags once they have been set. It creates a backdoor function which resets the changed flag on the value, allowing end users to forcibly overwrite flag values. The backdoor function is used to avoid modifying any of the go/flag compatible interfaces.

If this pattern is approved, it will need to be reproduced for all Slice and Array flag types.

[CLAassistant]

All committers have signed the CLA.

[eparis]

I'm not sure I know how this would get used. What would cause a Replace()? How would I trigger such a thing from the command line?

[therealmitchconnors]

Hey Eric, I should have noted that Steve and I discussed this offline. All of the flag values except arrays and slices overwrite on Set(). This is useful when you want to override the command line values. For example, see istio/istio#16143. I am considering how we might add interfaces specific to slice and array to accommodate not only Replace, but also Set() for cases where csv parsing goes awry (see the PR I commented on this afternoon). Mitch

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On Tue, Aug 13, 2019, 5:28 PM Eric Paris ***@***.***> wrote: I'm not sure I know how this would get used. What would cause a Replace()? How would I trigger such a thing from the command line? — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#215?email_source=notifications&email_token=AAGIQFWOQ4OYC5T7QZZTWG3QENGUFA5CNFSM4ILNUC4KYY3PNVWWK3TUL52HS4DFVREXG43VMVBW63LNMVXHJKTDN5WW2ZLOORPWSZGOD4HLNDY#issuecomment-521057935>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AAGIQFXEQFTI4QCK6R6JXJTQENGUFANCNFSM4ILNUC4A> .

[therealmitchconnors]

Replaced by #216