in= was problimatic in two ways. First, it referred to a remote by name,
but preferred content expressions can be evaluated elsewhere, where that
remote doesn't exist, or a different remote has the same name. This name
lookup code could error out at runtime. Secondly, in= seemed pretty useless.
in=here did not cause content to be gotten, but it did let present content
be dropped.
present is more useful, although "not present" is unstable and should be
avoided.
When in a subdir, both the normal filepath, and the filepath relative to
the top of the git repo are needed for matching. The former for key lookup,
and the latter for include/exclude to match against. Previously, key lookup
didn't work in this situation.
I'm using transfer for most things, both removable drives and cloud
storage, because it's the safest choice. We'll see if it makes sense
to prompt for the group when setting this up, or let the user pick
something else after the fact.
I've designed these to work well together, I hope. If I get it wrong,
I can just change the code in one place, since these expressions
won't be stored in the git-annex branch.
Solves the issue with preferred content expressions and dropping that
I mentioned yesterday. My solution was to add a parameter to specify a set
of repositories where content should be assumed not to be present. When
deciding whether to drop, it can put the current repository in, and then
if the expression fails to match, the content can be dropped.
Using yesterday's example "(not copies=trusted:2) and (not in=usbdrive)",
when the local repo is one of the 2 trusted copies, the drop check will
see only 1 trusted copy, so the expression matches, and so the content will
not be dropped.
This includes a full parser for the boolean expressions in the log,
that compiles them into Matchers. Those matchers are not used yet.
A complication is that matching against an expression should never
crash git-annex with an error. Instead, vicfg checks that the expressions
parse. If a bad expression (or an expression understood by some future
git-annex version) gets into the log, it'll be ignored.
Most of the code in Limit couldn't fail anyway, but I did have to make
limitCopies check its parameter first, and return an error if it's bad,
rather than erroring at runtime.
