metadata-less FileTree repository support - part I

Historically FileTree repositories have attempted to preserve the
Monticello metadata: version history and method timestamps. This was
done to make it easier for folks to take FileTree for a spin without
losing the Monticello version history. Monticello packages could be
moved into and out of FileTree repositories without any evidence that
part of their lives was spent in a git repository.

As more folks have begun using FileTree repositories and GitHub and with
packages spending their entire lives in git repositories, the Monticello
meta data has become more of an annoyance than a useful feature.

The files where the Monticello metadata is kept in FileTree are modified
on nearly every commit and can be the source of git merge conflicts. To
ameliorate this problem, Thierry Goubier[1] created
GitFileTree-MergeDriver[2] which took advantage of the git merge hooks
and ran code in Pharo to automatically resolve the merge conflicts for
version and method timestamps. The GitFileTree-MergeDriver works great
on your local disk, but when merging changes on GitHub for pull requests
the GitFileTree-MergeDriver cannot be used and it becomes impossible to
simply press the "Merge pull request" button and you have to manually do
the merge on your local disk -- of course GitFileTree-MergeDriver works
there, but it is annoying to not be able to do automatic merges.

The only real solution to this problem is to stop storing Monticello
metadata in a FileTree repository.

About 3 years ago, I added a "Cypress package feature" to Metacello[4]
so that Monticello meta data was not needed when using a BaselineOf to
load packages from a FileTree repository --- for those who are not
aware, standard Metacello only loads packages with newer Monticello
version numbers (part of the version history). The feature was a little
bit ahead of it's time, as there were very few developers actually using
GitHub for their Smalltalk projects.

Alon about the same time, Thierry created GitFileTree a variant of
FileTree for Pharo that hooks into the Monticello Browser and fabricates
the Monticello metadata from the Git meta data, making the metadata file
obsolete. GitFileTree made it practical for Pharo developers to use
FileTree much like tODE has made it practical to use git for
GemStone/GsDevKit projects.

8 months or so ago, Thierry added a metadata-less option to GitFileTree
where for GitFileTree the version history and method timestamp files
were no longer written/updated. To control this option, Thierry added a
"Metadata" field to the repository properties file, so that users could
choose whether or not they wanted to preserve Monticello meta data.

About 6 months ago, during a discussion on the Pharo list[3], the
question of Monticello meta data came up and I became aware of the
metadata-less feature and at the time there was interest in being able
to use the "Metacello Cypress package support" with GitFileTree
repositories and began thinking that perhaps it was finally time to blow
the dust off of "Metacello Cypress packages" and add a metadata-less
feature to the GemStone FileTree implementation.

So here we are a mere 6 months later and I've finally gotten around to
taking action with 3 pending pull requests:

   - PR #198: add a metadata-less option to GemStone FileTree
repositories[5]
   - PR #401: official support for "Metacello Cypress packages"[6]
   - PR #12: performance improvement for creating snapshots in
GLASS/GsDevKit

Over the next day or so, I plan to merge these pull requests into the
master branches.

If you have any questions about these new features, now is a good time
to ask.

Dale

[1] https://github.com/ThierryGoubier
[2]
https://github.com/ThierryGoubier/GitFileTree-MergeDriver#gitfiletree-mergedriver
[3] http://forum.world.st/Contributing-to-Pharo-tc4871604.html#none
[4]
https://github.com/dalehenrich/metacello-work/commits/master/repository/Metacello-Cypress.package
[5] https://github.com/dalehenrich/filetree/pull/198
[6] https://github.com/dalehenrich/metacello-work/pull/401
[7] https://github.com/glassdb/glass/pull/12
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