[RFC] Thoughts on ignore files

[Jelmer Vernooij]

At the moment ignore files in the three major distributed version
control systems (git, mercurial, bzr) are versioned inside of the tree.
The names and syntaxes of these files are different, so it is not
possible to import data from one system and then have ignores work
magically on the other.

If you convert e.g. a mercurial branch to a bazaar branch you end up
with a .hgignore file that Bazaar will not use. Converting this file to
a .bzrignore file on the fly seems ideal but is not possible for a
couple of reasons:

 * there is no one-to-one lossless back and forth mapping (and not
losslessly mapping would mean breaking referential integrity)
 * what if a .bzrignore file is already present?

Right now the working tree determines what format ignore files are
supported. It would be nice if Bazaar could support reading and updating
whatever ignore file is present rather than supporting just .bzrignore.
This could for example be done through a registration mechanism.

Of course, it would still be nice if ignores could be tree metadata
rather than part of the tree contents. This proposal does not conflict
with such a change.

Thoughts?

Cheers,

Jelmer