Re: [StGIT RFC] Changing patch@branch syntax

From: Yann Dirson <ydirson@altern.org>
Date: Jun 21, 2007, 23:02 UTC
Message-ID: <20070621230207.GD7730@nan92-1-81-57-214-146.fbx.proxad.net>
In-Reply-To: <20070522210020.GV19253@nan92-1-81-57-214-146.fbx.proxad.net>

Working in the implementation of hydras/pools, as well as discussing of their future, led me to the following thoughts, quite related to how we should select a new syntax for patches.

First, as a foreword, a bit if refactoring: I think we should use some sort of Stackable (maybe pick a better name) class as a parent for Patch and PatchSet. Instances of a Stackable would be candidates to be members of a PatchSet. That means we can have stacks within a stack, as well as stacks members of a pool. But we also need a syntax to name stacks-(in-a-stack)*, and patches within them.

Second, but not least, we currently have an ambiguity in syntax: "foo" can mean "patch foo in current branch" or "branch foo", depending on the context, and that is *really* bad. What's more, my former proposal (quoted below) does not improve this issue. And my previous proposal, which suggested using a prefix like "/stack/patch" for a fully qualified patch and "patch" for a relative one does not solve that problem either, and brings the additional annoyance of introducing a syntax that is incompatible with git-core.

So here is a new proposal, which I believe would address all current issues, at the expense of changing stgit syntax. The idea is to use a single separator for all levels of Stackable objects, with an optional "patch id" (eg. //top) at the end when meaningful. Only names would be possible to omit, separators would be mandatory to specify the nesting level. That gives a syntax of:

	[patchset]([:stackable]+(//id)?)*

Examples:

	<stack>			the named branch (git-compatible)
	<stack>:<patch>		named patch in named stack
	:<patch>		named patch in current patchset (currently just "<patch>")
	<stack>:		current (top) patch in named patchset
	<pool>:<stack>:<patch>	fully-qualified patch in a named hydra
	::			top patch of the current stack of an hydra
	:<stack>://bottom.old	previous bottom of the top patch in the named stack of current pool

How does that feel ?

On Tue, May 22, 2007 at 11:00:20PM +0200, Yann Dirson wrote:

Show 18 quoted lines

> Following the "stg pick" example above, would we also want to allow
> picking from a remote repo ?  Then the URL fragment notation could be
> suited, and we could have something like:
> 
> 	http://full/path/to/repo#my/branch:my/patch//top
> 
> That is, a formal syntax of:
> 
> 	[[[repo#]branch:]patch][//modifier]
> 
> Going further, since specifying a repo without a branch probably has
> no meaning (unless we want to default to the HEAD branch), we could
> simplify to the following:
> 
> 	[[[repo#]branch#]patch][//modifier]
> 
> I don't think we really want to allow "repo#patch", meaning that patch
> on the current branch, as this gets easily confused by branch switching.