Re: [RFC PATCH v3 8/8] --sparse for porcelains

From: Johannes Schindelin <johannes.schindelin@gmx.de>
Date: Aug 17, 2009, 09:08 UTC
Message-ID: <alpine.DEB.1.00.0908171101090.4991@intel-tinevez-2-302>
In-Reply-To: <alpine.DEB.1.00.0908161002460.8306@pacific.mpi-cbg.de>

Hi,

On Sun, 16 Aug 2009, Johannes Schindelin wrote:

Show 34 quoted lines

> [...] if you want to say that assume-unchanged and sparse are two 
> fundamentally different things, I would be interested in some equally 
> convincing argument as for the shallow/graft issue.
> 
> There is a fundamental difference, I grant you that: the working 
> directory does not contain the "sparse'd away" files while the same is 
> not true for assume-unchanged files.
> 
> But does that matter?  The corresponding files are still in the index 
> and the repository.
> 
> IOW under what circumstances would you want to be able to discern 
> between assume-unchanged and "sparse'd away" files in the working 
> directory?
> 
> I could _imagine_ that you'd want a tool that allows you to change the 
> focus of the sparse checkout together with the working directory.  
> Example: you have a sparse checkout of Documentation/ and now you want 
> to have t/, too.  Just changing .git/info/sparse will not be enough.
> 
> The question is if the tool to change the "sparseness" [*1*] should not 
> change .git/info/sparse itself; if it does not, it would be good to be 
> able to discern between the "assume-unchanged" and "sparse'd away" 
> files.
> 
> Although it might be enough to traverse the index and check the presence 
> of the assume-unchanged files in the working directory to determine 
> which files are sparse, and which ones are merely assume-unchanged.
> 
> Ciao,
> Dscho
> 
> Footnote [*1*]: I think we need some nice and clear nomenclature here.  
> Any English wizards with a good taste of naming things?

Turns out that somebody on IRC had a problem that requires to have sparse'd out files which _do_ have working directory copies.

So just having the assume-changed bit may not be enough.

The scenario is this: the repository contains a file that users are supposed to change, but not commit to (only the super-intelligent inventor of this scenario is allowed to). As this repository is originally a subversion one, there is no problem: people just do not switch branches.

But this guy uses git-svn, so he does switch branches, and to avoid committing the file by mistake, he marked it assume-unchanged. Only that a branch switch overwrites the local changes.

I suggested the use of the sparse feature, and mark this file (and this file alone) as sparse'd-out.

Is this an intended usage scenario? Then we cannot reuse the assume-changed bit [*1*].

Ciao, Dscho

Footnote [*1*]: in this particular scenario, we could still discern between sparse'd-out and regular assume-unchanged file, because .git/info/sparse knows about the file. But the design is now brittle, and it is not hard at all to come up with a situation where it breaks.