[Monotone-devel] Re: Subdirectory support

[graydon hoare]

Adam Logghe wrote:

> I think the answer changes depending on how much you are editing
> upstream and importing upstream changes. Trying to track lots of changes
> in your dependencies is going to hurt no matter the tool.

there are a few things you might mean by "subdirectory support":

1: running monotone in a subdirectory and having it jump up a few dirs
   to find the MT/ dir above it
   1.1: having this cause the command to *act* only on the files in the
        invoked subdirectory, such as diffing a subdir.
   1.2: making it possible to check out, edit, and commit a subset of
        a complete tree, never actually seeing the whole tree due to
        some sort of sticky, persistent "mask".
   1.3: coming up with some sensible form of merging partial trees,
        say by committing your partial merge to each side of a fork

2: storing some kind of "link to another project marker" such that
   checking out a "super-tree" checks out a bunch of "sub-trees" from
   different histories / branches / organizations automatically.

now, I think we've already decided on #1 as being desirable, achievable, 
necessary. no problem there aside from finding time to implement it.

I think I know a pretty simple way to do #2 using "today's technology" 
though: make a persistent file attribute in .mt-attrs called, say, "module":

path/to/subproject module 607a036b350db1d65291d2520ec0a0d22630eb5c
other/project      module 435e816c30263c9184f94e7c4d5aec78ea7c028a

then add the following to the std_hooks.lua file:

attr_functions["module"] =
   function(dir, hash)
      if (os.execute("test -d " .. dir) ~= 0) then
        io.write("checking out module in " .. dir)
        os.execute("monotone co " .. dir .. " " .. hash))
      end
   end

this is essentially a rip-off of arch's "configs", except it works "out 
of the box" and would be relatively painless to switch a directory from 
being a normal directory to being a module (independently versionned): 
just make a new manifest for the subtree, drop the subtree from the 
parent, and add a module link. you could even make an integrated command 
to do this, and to re-attach a module to the parent, if you change your 
mind. I've been considering making some utility commands for managign 
the .mt-attrs file anyways.

the only difficulty I can see with this is informing, say, netsync that 
you need to pull the subtree along for the ride (else you won't *have* 
the subtree on hand to checkout). easiest approach there would be to 
name the subtree branches with a common prefix, and serve the prefix as 
a collection. this is not too hard, since branches can overlap; you can 
for example pick up a 3rd party library (also using monotone) and give 
it a branch name in "your" namespace.

-graydon