[PATCH 1 of 5] extdata: add extdatasource reader

[Matt Mackall]

On Thu, 2016-10-06 at 07:52 +0200, Mathias De Maré wrote:
> On Thu, Sep 22, 2016 at 8:21 PM, Matt Mackall <mpm at selenic.com> wrote:
> 
> > 
> > # HG changeset patch
> > # User Matt Mackall <mpm at selenic.com>
> > # Date 1473794045 18000
> > #      Tue Sep 13 14:14:05 2016 -0500
> > # Node ID 19bf2776dfe39befdc479253e1e7d030b41c08f9
> > # Parent  5271ae66615207f39cc41d78f4541bc6f8ca6ff6
> > extdata: add extdatasource reader
> > 
> > This adds basic support for extdata, a way to add external data
> > sources for revsets and templates. An extdata data source is simply a
> > list of lines of the form:
> > 
> > <revision identifier>[<space><freeform text>]\n
> > 
> > An extdata source is configured thusly:
> > 
> > [extdata]
> > name = <a url or path>
> > 
> > urls of the form shell: are launch shell commands to generate data.
> > 
> This looks great!
> We've been using a small extension to load an external file with tags into
> one of our repositories. Do you think that could fit here as well?
> 
> Something like this would be nice:
> [extdata]
> name = <a url or path>
> name.type = tags

Do you actually need it to be a 'tag' or is it good enough that it be a named
identifier in the current union of namespaces?

Extdata as presently designed doesn't add new names for nodes to the namespaces.
But having a way to import an arbitrary name mapping would indeed be handy. For
instance, for having a mapping to other version control system identifiers.

> name.checkrev = <revisions that should be present in the repository before
> loading the tags>

Can you explain more about checkrev?

-- 
Mathematics is the supreme nostalgia of our time.