What: GIT - Fast Version Control System
 Where: http://git-scm.com/
        http://www.gitscm.org/
        http://ozlabs.org/~paulus/gitk/
 Description: 
       Git is popular version control system designed to handle 
       very large projects with speed and efficiency; 
       it is used mainly for various open source projects, most notably the Linux kernel.
       Currently at version v1.6.1.2
 Updated: 02/2009
 Contact: See web site

It is related to Tcl/Tk because there is [gitk], a history visualization tool written in Tcl/Tk.

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Branches in git are kind of like variables in Tcl. 
When one makes a commit, one creates a commit object, that "contains" the parent commit(s) and a directory tree specifying the current state of one's working directory, kind of like:
 proc commit {} {
    upvar #0 $::current_branch current
    set current [list commit $::current_tree $current]
 }
(Rather than referencing things with pointers to [Tcl_Obj]s however, things are referenced with 160-bit [sha1] hashes.) 
Deleting a branch is like unsetting a variable: if that variable held the only reference to a particular value (commit), then the commit is gone too, but if anything else held another reference (e.g., it was merged into another branch, which results in a commit with more than one parent), then the commit is still there.

Of course, since all of it is stored on disk, it would be impractical to use a refcount scheme to reclaim unused memory. Instead git has a garbage collector git-gc. Until that is run, deleted commits (and whatever) can still be accessed by giving explicit hash numbers.

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[Zarutian] 16. july 2007: Can git be obtained or compiled into a multiplatform starkit?
Hard when one has only an thumbdrive/ipod to store stuff.

[Lars H], 2008-06-05: Since it's a Unixy collection of many programs that do one thing each, I suspect this would be tricky (can't [exec] something in a [vfs], can you?). Apparently there has been some work [http://git.or.cz/gitwiki/SoC2007Projects#head-f604c29a605c7c5fe1e993ef5aa74ce34f3fb84e] on turning it into a library, but that only got part of the way.

Makes me wonder, though… Could there be a semi-automatic way of turning a suite of C programs (like git, or at least the git plumbing) into a [load]able extension which exposes each program as a Tcl command? (I expect one would have to do things like turning static C variables into fields of some dynamically allocated struct, to ensure reentrancy, but C is not my forte.)

FWIW, I later noticed that git has a concept of '''builtin''' command, with something rather close to a Tcl_CmdProc for every built-in subcommand of git. Probably not too hard to wrap manually, provided the built-in commands don't try to exec each other.

[MAKR] 2009-02-01: I updated the URLs as the main site apparently changed recently. 
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A thing that seems to be special about Git is that it tracks content (e.g. procedure definitions) rather than files (as [CVS], [SVN], and [Mercurial] does). 
See [http://wincent.com/a/about/wincent/weblog/archives/2007/07/a_look_back_bra.php].

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[Category Application] |
[Category Dev. Tools]