Re: Git Evolve

From: Derrick Stolee <stolee@gmail.com>
Date: Oct 1, 2018, 12:37 UTC
Message-ID: <5539c3ab-9c55-fc9a-6e78-9ab128cc30bc@gmail.com>
In-Reply-To: <CAPL8ZivFmHqS2y+WmNR6faRMnuahiqwPVYsV99NiJ1QLHOs9fQ@mail.gmail.com>

On 9/29/2018 7:00 PM, Stefan Xenos wrote:

> Hello, List!

Hello! Welcome.

> I'm interested in porting something like Mercurial's evolve command to
> Git. I'll be following up with a formal proposal shortly, but before I
> do I thought I'd introduce myself to the list and find out if anyone
> else is interested in this topic.

I'm CC'ing some contributors who have also expressed interest in this topic.

> What is the evolve command?

I'm snipping the rest of your thread because I'm vaguely familiar with how this is used in hg, but I haven't used it myself. Instead, I'm going to ask you the same questions I asked the last time I had a conversation about this with someone. In my opinion, these questions should have good answers before we start working on the solution, or else we could paint ourselves into a corner as we build the first pieces.

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What would the command-line experience look like for this workflow? Be specific, including examples!

How does one create a commit that obsoletes another? Are we in the middle of an interactive rebase, or are we simply checking out the commit? How does a use keep track of their progress in a topic?

How do I view which commits in my topic are obsolete, and to what commits?

If I want to obsolete commits on one machine and then finish the work on another machine, how do I do that? Similarly: how can I share obsolete commits with other users so they can apply them (or not)?

Do obsolescence markers live in the ref space? (This is one way to help answer the question above.)

Can I make multiple commits obsolete into one commit (merge patches)? Can I make my commit obsolete in multiple ways (split a patch)? How is this communicated to the user?

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In my opinion, a good way to move forward is to create a patch that adds a design document to Documentation/technical that answers these questions. Then we can dig in more to make the vision clearer.

I'm not a UX expert, but this seems like a place where we could use someone with expertise in the area. If we are not careful, we could end up with something even harder to use than interactive rebase. The main goal here is to make it easy to rewrite a topic (plus, the ability to do so in stages).

I look forward to see what goes on in this space. Count me in to review the technical details.

Thanks, -Stolee