http://www.euclideanspace.com/software/development/github/workflow/
I'm not sure if this diagram is quite right. I get the impression that
the 'git checkout' command swaps around the directory contents and I
don't know how to show that.
Now you have 3 boxes trunk, master, fricas. I don't quite get their meaning.
The best thing to think about a git repository is in terms of a Directed
Acyclic Graph (DAG) of commits. Consider this graph being labelled with
the sha-1 numbers. Since identical sha-1 numbers mean identical content,
it doesn't matter where in the world that content is stored. Now,
consider the fricas git repo. that consists of all commits that lead to
the master branch of https://github.com/hemmecke/fricas-svn
In fact, I have another DAG here. https://github.com/hemmecke/fricas
And you have a DAG here. https://github.com/martinbaker/fricas
All three are probably different, but they share quite a big part.
Consider the "fricas git repository" simply as "the repository of every
commit that anyone in the world has ever committed to fricas", i.e. you
consider the union of all commits over all users. That gives a HUGE DAG
(let's call it FRICAS). But by the sha-1 numbers, you are sure that all
the three repos above just form a subgraph of FRICAS. All we are doing
with git, is to modify and extend this FRICAS DAG.
Now, whenever you say "git checkout some-sha-1" git will switch the
files in your working directory to contain exactly the state
corresponding to "some-sha-1".
It's usually. not a big deal to work in the same directory. Git never
override a modified file by "git checkout", but rather aborts and tells
you that you have uncommitted changes. It's actually very hard to lose
some data with git.
Your picture is wrong in so far as you should have just one clone
corresponding to your https://github.com/martinbaker/fricas .
Let's call this clone "fricas". "fricas" has two "remotes" (which you
see by "git remote -v"). Namely,
origin https://github.com/martinbaker/fricas
upstream https://github.com/hemmecke/fricas-svn
You can fetch data from any of these remotes. (Remember the big FRICAS
DAG. Basically, with adding more and more remotes, you have access to a
bigger part of FRICAS. But one usually only concentrates on a few
remotes (like upstream) and ignores what other people do with fricas.)
trunk and master are just local names for branches. Nothing fancy with
these names. The important things are actually the sha-1's.
It looks as the fricas box in your picture is the so-called working
directory whereas the trunk and master boxes correspond to branches.
BTW, instead of "git merge" I have suggested "git rebase" in my previous
mail. Learn about this difference. Since we still have to deal with an
SVN official repository, that does matter.
http://book.git-scm.com/4_rebasing.html
http://gitready.com/intermediate/2009/01/31/intro-to-rebase.html
Ralf
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