[Monotone-devel] Re: renaming branches (was Re: Ideas and questions.)

[graydon hoare]

Jeremy Fincher wrote:

> I'm not sure if this is necessary, or if it's a good thing to enforce.  
> People *will* pick duplicate branch names.  There is no doubt in my mind 
> that many people will have branches named "bugs" or "main" or "dev", 
> etc.  No matter how many times we say, "Pick a globally unique name!" 
> people still will not do so.  I think, rather than have the database 
> *enforce* unique human-readable names, we should instead have the user 
> disambiguate such collisions himself.

I think you misunderstand what I mean. I mean that in one user's 
database, they would have a 1:1 mapping between an "alias" and a branch 
ID. other users, in other databases, could have different (or colliding) 
aliases. but the user would not have either of these cases:

  - 2 aliases mapping to the same branch ID in a database
  - 1 alias mapping to two different branch IDs in a database

I want to prohibit those, at a UI level, because it makes the UI 
significantly more surprising and hard to predict.

> Of course, this wouldn't be very user-friendly if the user had to 
> disambiguate branch names *every* time, so I suggest that we cache the 
> user's decision in some way that's easily editable/readable by the user: 
> either a dotfile in his home directory or a file in MT/.  We could keep 
> a mapping of human-readable names to random ids, and use that first when 
> we're given a branch name by the user.

that mapping, which you just described, is the 1:1 mapping I'm talking 
about. I think it would be fine to keep it in your database, even send 
it to another user as "advice" when you're syncing. I'm not talking 
about a global 1:1 relationship, just locally, per-database.

> A nice side effect of that functionality is that the user could use 
> shorter names for branches, if he so chose.  Also, in the case that 
> Alice wants to work with Bob's "dev" branch and Cindy's "dev" branch, 
> she can have a different "nickname" for each and work with both 
> perfectly fine.

yes, we're more or less talking about the same thing. though, if you 
ever want to push your work out the wider world, it'd be good to pick a 
global-ish name at that point.

> That's one of the nice things about the method I propose; if a user has 
> setup a nickname for the branch, he won't be bothered at all by a 
> rename.  Behind the scenes, his database would accept it, but since the 
> randomly generated *actual* branch name didn't change, his aliases will 
> continue to work as before.

again, this much is the same between what I said and what you said.

> With user-overridable aliases, he could just insert a temporary alias 
> for the other branch, merge the differences into his own branch, and 
> remove the old alias.  No database pollution at all.

.. I think the only difference here is whether you happen to have two 
branches with the same alias, or you rename one first. imo not much 
difference.

> I doubt it has some flaw you haven't foreseen.  At least, I hope not, 
> because this is the same solution I thought of when I was thinking about 
> the issue of globally unique branch names :)

oh, never underestimate njs' uncanny ability to crush your finest ideas 
into a paste :)

-graydon