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-rw-r--r--git.org44
1 files changed, 26 insertions, 18 deletions
diff --git a/git.org b/git.org
index 59f6c77..7292502 100644
--- a/git.org
+++ b/git.org
@@ -1,8 +1,11 @@
-* democratized Version Control Systems (dVCS)
+* dVCS by way of git
- Sharing complete repositories is a simple concept which poses subtle
- constraints in whose solution yields a form of democratized version
- control.
+ Sharing complete repositories is a simple concept which involves a
+ subtle paradigm shift, which in turn opens up interesting new
+ pastures.
+
+ In this talk I will demonstrate some of these constraints
+ and their solutions, as implemented in git.
* A look back at SVN
@@ -22,7 +25,7 @@
Obviously this was all workable, but it didn't exactly engender
itself to lazy people like myself. The existance and popularity of
CVSup in spite of being written in Modula 3 shows the value of
- repository sharing.
+ repository sharing. You can think of git as CVSup done right.
* Constraints
@@ -30,7 +33,7 @@
So:
-*** Linear history is a thing of the past
+*** Offline operation means history is frequently not linear
*** Merging must be easy
*** Sharing changes must be easy
@@ -40,13 +43,13 @@
Time is no longer a useful identifier when comparing the history of
disparate repositories, and thus can't be used for commit
- identifiers.
+ identifiers. Something new must be found.
-** git uses SHA hashes to identify repository objects
+*** git uses SHA hashes to identify repository objects
- SHA is a critical factor in determining correct sharing of file
- data. The hash is computed from file contents and mapped to
- file names.
+ SHA-1 hashes are the basic identifier of every object in the git
+ system, which yields a bunch of nice properties we'll get into
+ later.
** Merging is elevated to a first class operation
@@ -85,9 +88,7 @@
its contents. The hash is easy to compute and provides good entropy
properties when building a hash table.
-*** History is immediately verifiable (barring hash collisions)
-
-*** Some measure of security comes for free
+**** Some measure of security comes for free
All commits are effectively signed by all their previous commits, so
verifying a repository becomes trivial given only a valid commit id.
@@ -95,8 +96,9 @@
** merge commits
In git, a commit can have many parents, as opposed to SVN where a
- commit can have only one parent. Merge commits can also contain
- blobs themselves to mark conflict resolutions.
+ commit can have only one parent. All commits contain a tree, so when
+ you had to resolve conflicts from a merge, those will be contained
+ in the commit's tree object.
** SHA hashes are a pain to type
@@ -107,9 +109,12 @@
*** tags are fixed refs
- Tags have optional descriptions and GPG signatures.
+ Tags always refer to a commit, but can also contain a cryptographic
+ signature and message, in which case the ref points to a tag object,
+ which, in turn, points to a commit. For almost any use of tags, you
+ don't need to care about this, since git is fairly smart about it.
-*** branches and HEAD
+*** branches and HEAD are symbolic refs
Branches are moving refs and always reference their tips. HEAD is a
pointer to the tip of the current branch.
@@ -176,6 +181,9 @@
# Git - SVN Crash Course
<http://git.or.cz/course/svn.html>
+ # GitWiki
+ <http://git.or.cz/gitwiki/Git>
+
# Git User's Manual
<http://www.kernel.org/pub/software/scm/git/docs/user-manual.html>