


PERLREPOSITORY(1)Perl Programmers Reference GuidPERLREPOSITORY(1)


NAME
       perlrepository - Using the Perl source repository

SYNOPSIS
       All of Perl's source code is kept centrally in a Git
       repository at perl5.git.perl.org. The repository contains
       many Perl revisions from Perl 1 onwards and all the
       revisions from Perforce, the version control system we
       were using previously. This repository is accessible in
       different ways.

       The full repository takes up about 80MB of disk space. A
       check out of the blead branch (that is, the main
       development branch, which contains bleadperl, the
       development version of perl 5) takes up about 160MB of
       disk space (including the repository). A build of
       bleadperl takes up about 200MB (including the repository
       and the check out).

GETTING ACCESS TO THE REPOSITORY
   READ ACCESS VIA THE WEB
       You may access the repository over the web. This allows
       you to browse the tree, see recent commits, subscribe to
       RSS feeds for the changes, search for particular commits
       and more. You may access it at:

         http://perl5.git.perl.org/perl.git

       A mirror of the repository is found at:

         http://github.com/github/perl

   READ ACCESS VIA GIT
       You will need a copy of Git for your computer. You can
       fetch a copy of the repository using the Git protocol
       (which uses port 9418):

         git clone git://perl5.git.perl.org/perl.git perl-git

       This clones the repository and makes a local copy in the
       perl-git directory.

       If your local network does not allow you to use port 9418,
       then you can fetch a copy of the repository over HTTP
       (this is slower):

         git clone http://perl5.git.perl.org/perl.git perl-http

       This clones the repository and makes a local copy in the
       perl-http directory.

   WRITE ACCESS TO THE REPOSITORY
       If you are a committer, then you can fetch a copy of the
       repository that you can push back on with:



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         git clone ssh://perl5.git.perl.org/gitroot/perl.git perl-ssh

       This clones the repository and makes a local copy in the
       perl-ssh directory.

       If you cloned using the git protocol, which is faster than
       ssh, then you will need to modify your config in order to
       enable pushing. Edit .git/config where you will see
       something like:

         [remote "origin"]
         url = git://perl5.git.perl.org/perl.git

       change that to something like this:

         [remote "origin"]
         url = ssh://perl5.git.perl.org/gitroot/perl.git

       NOTE: there are symlinks set up so that the /gitroot is
       optional and since SSH is the default protocol you can
       actually shorten the "url" to
       "perl5.git.perl.org:/perl.git".

       You can also set up your user name and e-mail address. For
       example

         % git config user.name "Leon Brocard"
         % git config user.email acme@astray.com

       It is also possible to keep "origin" as a git remote, and
       add a new remote for ssh access:

         % git remote add camel perl5.git.perl.org:/perl.git

       This allows you to update your local repository by pulling
       from "origin", which is faster and doesn't require you to
       authenticate, and to push your changes back with the
       "camel" remote:

         % git fetch camel
         % git push camel

       The "fetch" command just updates the "camel" refs, as the
       objects themselves should have been fetched when pulling
       from "origin".

       The committers have access to 2 servers that serve
       perl5.git.perl.org.  One is camel.booking.com, which is
       the 'master' repository. The perl5.git.perl.org IP address
       also lives on this machine. The second one is
       dromedary.booking.com, which can be used for general
       testing and development. Dromedary syncs the git tree from
       camel every few minutes, you should not push there. Both
       machines also have a full CPAN mirror.  To share files



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       with the general public, dromedary serves your
       ~/public_html/ as
       http://users.perl5.git.perl.org/~yourlogin/

OVERVIEW OF THE REPOSITORY
       Once you have changed into the repository directory, you
       can inspect it.

       After a clone the repository will contain a single local
       branch, which will be the current branch as well, as
       indicated by the asterisk.

         % git branch
         * blead

       Using the -a switch to "branch" will also show the remote
       tracking branches in the repository:

         % git branch -a
         * blead
           origin/HEAD
           origin/blead
         ...

       The branches that begin with "origin" correspond to the
       "git remote" that you cloned from (which is named
       "origin"). Each branch on the remote will be exactly
       tracked by theses branches. You should NEVER do work on
       these remote tracking branches. You only ever do work in a
       local branch. Local branches can be configured to
       automerge (on pull) from a designated remote tracking
       branch. This is the case with the default branch "blead"
       which will be configured to merge from the remote tracking
       branch "origin/blead".

       You can see recent commits:

         % git log

       And pull new changes from the repository, and update your
       local repository (must be clean first)

         % git pull

       Assuming we are on the branch "blead" immediately after a
       pull, this command would be more or less equivalent to:

         % git fetch
         % git merge origin/blead

       In fact if you want to update your local repository
       without touching your working directory you do:

         % git fetch



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       And if you want to update your remote-tracking branches
       for all defined remotes simultaneously you can do

         % git remote update

       Neither of these last two commands will update your
       working directory, however both will update the remote-
       tracking branches in your repository.

       To switch to another branch:

         % git checkout origin/maint-5.8-dor

       To make a local branch of a remote branch:

         % git checkout -b maint-5.10 origin/maint-5.10

       To switch back to blead:

         % git checkout blead

   FINDING OUT YOUR STATUS
       The most common git command you will use will probably be

         % git status

       This command will produce as output a description of the
       current state of the repository, including modified files
       and unignored untracked files, and in addition it will
       show things like what files have been staged for the next
       commit, and usually some useful information about how to
       change things. For instance the following:

         $ git status
         # On branch blead
         # Your branch is ahead of 'origin/blead' by 1 commit.
         #
         # Changes to be committed:
         #   (use "git reset HEAD <file>..." to unstage)
         #
         #       modified:   pod/perlrepository.pod
         #
         # Changed but not updated:
         #   (use "git add <file>..." to update what will be committed)
         #
         #       modified:   pod/perlrepository.pod
         #
         # Untracked files:
         #   (use "git add <file>..." to include in what will be committed)
         #
         #       deliberate.untracked

       This shows that there were changes to this document staged
       for commit, and that there were further changes in the



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       working directory not yet staged. It also shows that there
       was an untracked file in the working directory, and as you
       can see shows how to change all of this. It also shows
       that there is one commit on the working branch "blead"
       which has not been pushed to the "origin" remote yet.
       NOTE: that this output is also what you see as a template
       if you do not provide a message to "git commit".

       Assuming we commit all the mentioned changes above:

         % git commit -a -m'explain git status and stuff about remotes'
         Created commit daf8e63: explain git status and stuff about remotes
          1 files changed, 83 insertions(+), 3 deletions(-)

       We can re-run git status and see something like this:

         % git status
         # On branch blead
         # Your branch is ahead of 'origin/blead' by 2 commits.
         #
         # Untracked files:
         #   (use "git add <file>..." to include in what will be committed)
         #
         #       deliberate.untracked
         nothing added to commit but untracked files present (use "git add" to track)

       When in doubt, before you do anything else, check your
       status and read it carefully, many questions are answered
       directly by the git status output.

SUBMITTING A PATCH
       If you have a patch in mind for Perl, you should first get
       a copy of the repository:

         % git clone git://perl5.git.perl.org/perl.git perl-git

       Then change into the directory:

         % cd perl-git

       Alternatively, if you already have a Perl repository, you
       should ensure that you're on the blead branch, and your
       repository is up to date:

         % git checkout blead
         % git pull

       It's preferable to patch against the latest blead version,
       since this is where new development occurs for all changes
       other than critical bug fixes.  Critical bug fix patches
       should be made against the relevant maint branches, or
       should be submitted with a note indicating all the
       branches where the fix should be applied.




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       Now that we have everything up to date, we need to create
       a temporary new branch for these changes and switch into
       it:

         % git checkout -b orange

       which is the short form of

         % git branch orange
         % git checkout orange

       Then make your changes. For example, if Leon Brocard
       changes his name to Orange Brocard, we should change his
       name in the AUTHORS file:

         % perl -pi -e 's{Leon Brocard}{Orange Brocard}' AUTHORS

       You can see what files are changed:

         % git status
         # On branch orange
         # Changes to be committed:
         #   (use "git reset HEAD <file>..." to unstage)
         #
         #     modified:   AUTHORS
         #

       And you can see the changes:

         % git diff
         diff --git a/AUTHORS b/AUTHORS
         index 293dd70..722c93e 100644
         --- a/AUTHORS
         +++ b/AUTHORS
         @@ -541,7 +541,7 @@    Lars Hecking                   <lhecking@nmrc.ucc.ie>
          Laszlo Molnar                  <laszlo.molnar@eth.ericsson.se>
          Leif Huhn                      <leif@hale.dkstat.com>
          Len Johnson                    <lenjay@ibm.net>
         -Leon Brocard                   <acme@astray.com>
         +Orange Brocard                 <acme@astray.com>
          Les Peters                     <lpeters@aol.net>
          Lesley Binks                   <lesley.binks@gmail.com>
          Lincoln D. Stein               <lstein@cshl.org>

       Now commit your change locally:

         % git commit -a -m 'Rename Leon Brocard to Orange Brocard'
         Created commit 6196c1d: Rename Leon Brocard to Orange Brocard
          1 files changed, 1 insertions(+), 1 deletions(-)

       You can examine your last commit with:

         % git show HEAD




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       and if you are not happy with either the description or
       the patch itself you can fix it up by editing the files
       once more and then issue:

         % git commit -a --amend

       Now you should create a patch file for all your local
       changes:

         % git format-patch origin
         0001-Rename-Leon-Brocard-to-Orange-Brocard.patch

       You should now send an email to perl5-porters@perl.org
       with a description of your changes, and include this patch
       file as an attachment.

       If you want to delete your temporary branch, you may do so
       with:

         % git checkout blead
         % git branch -d orange
         error: The branch 'orange' is not an ancestor of your current HEAD.
         If you are sure you want to delete it, run 'git branch -D orange'.
         % git branch -D orange
         Deleted branch orange.

   A note on derived files
       Be aware that many files in the distribution are
       derivative--avoid patching them, because git won't see the
       changes to them, and the build process will overwrite
       them. Patch the originals instead.  Most utilities (like
       perldoc) are in this category, i.e. patch utils/perldoc.PL
       rather than utils/perldoc. Similarly, don't create patches
       for files under $src_root/ext from their copies found in
       $install_root/lib.  If you are unsure about the proper
       location of a file that may have gotten copied while
       building the source distribution, consult the "MANIFEST".

   A note on binary files
       Since the patch(1) utility cannot deal with binary files,
       it's important that you either avoid the use of binary
       files in your patch, generate the files dynamically, or
       that you encode any binary files using the uupacktool.pl
       utility.

       Assuming you needed to include a gzip-encoded file for a
       module's test suite, you might do this as follows using
       the uupacktool.pl utility:

           $ perl uupacktool.pl -v -p -D lib/Some/Module/t/src/t.gz
           Writing lib/Some/Module/t/src/t.gz into lib/Some/Module/t/src/t.gz.packed

       This will replace the "t.gz" file with an encoded
       counterpart. During "make test", before any tests are run,



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       perl's Makefile will restore all the ".packed" files
       mentioned in the MANIFEST to their original name. This
       means that the test suite does not need to be aware of
       this packing scheme and will not need to be altered.

   Getting your patch accepted
       The first thing you should include with your patch is a
       description of the problem that the patch corrects.  If it
       is a code patch (rather than a documentation patch) you
       should also include a small test case that illustrates the
       bug (a patch to an existing test file is preferred).

       If you are submitting a code patch there are several other
       things that you need to do.

       Comments, Comments, Comments
           Be sure to adequately comment your code.  While
           commenting every line is unnecessary, anything that
           takes advantage of side effects of operators, that
           creates changes that will be felt outside of the
           function being patched, or that others may find
           confusing should be documented.  If you are going to
           err, it is better to err on the side of adding too
           many comments than too few.

       Style
           In general, please follow the particular style of the
           code you are patching.

           In particular, follow these general guidelines for
           patching Perl sources:

               8-wide tabs (no exceptions!)
               4-wide indents for code, 2-wide indents for nested CPP #defines
               try hard not to exceed 79-columns
               ANSI C prototypes
               uncuddled elses and "K&R" style for indenting control constructs
               no C++ style (//) comments
               mark places that need to be revisited with XXX (and revisit often!)
               opening brace lines up with "if" when conditional spans multiple
                   lines; should be at end-of-line otherwise
               in function definitions, name starts in column 0 (return value is on
                   previous line)
               single space after keywords that are followed by parens, no space
                   between function name and following paren
               avoid assignments in conditionals, but if they're unavoidable, use
                   extra paren, e.g. "if (a && (b = c)) ..."
               "return foo;" rather than "return(foo);"
               "if (!foo) ..." rather than "if (foo == FALSE) ..." etc.

       Testsuite
           When submitting a patch you should make every effort
           to also include an addition to perl's regression tests
           to properly exercise your patch.  Your testsuite



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           additions should generally follow these guidelines
           (courtesy of Gurusamy Sarathy <gsar@activestate.com>):

               Know what you're testing.  Read the docs, and the source.
               Tend to fail, not succeed.
               Interpret results strictly.
               Use unrelated features (this will flush out bizarre interactions).
               Use non-standard idioms (otherwise you are not testing TIMTOWTDI).
               Avoid using hardcoded test numbers whenever possible (the
                 EXPECTED/GOT found in t/op/tie.t is much more maintainable,
                 and gives better failure reports).
               Give meaningful error messages when a test fails.
               Avoid using qx// and system() unless you are testing for them.  If you
                 do use them, make sure that you cover _all_ perl platforms.
               Unlink any temporary files you create.
               Promote unforeseen warnings to errors with $SIG{__WARN__}.
               Be sure to use the libraries and modules shipped with the version
                 being tested, not those that were already installed.
               Add comments to the code explaining what you are testing for.
               Make updating the '1..42' string unnecessary.  Or make sure that
                 you update it.
               Test _all_ behaviors of a given operator, library, or function:
                 - All optional arguments
                 - Return values in various contexts (boolean, scalar, list, lvalue)
                 - Use both global and lexical variables
                 - Don't forget the exceptional, pathological cases.

ACCEPTING A PATCH
       If you have received a patch file generated using the
       above section, you should try out the patch.

       First we need to create a temporary new branch for these
       changes and switch into it:

         % git checkout -b experimental

       Patches that were formatted by "git format-patch" are
       applied with "git am":

         % git am 0001-Rename-Leon-Brocard-to-Orange-Brocard.patch
         Applying Rename Leon Brocard to Orange Brocard

       If just a raw diff is provided, it is also possible use
       this two-step process:

         % git apply bugfix.diff
         % git commit -a -m "Some fixing" --author="That Guy <that.guy@internets.com>"

       Now we can inspect the change:

         % git show HEAD
         commit b1b3dab48344cff6de4087efca3dbd63548ab5e2
         Author: Leon Brocard <acme@astray.com>
         Date:   Fri Dec 19 17:02:59 2008 +0000



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           Rename Leon Brocard to Orange Brocard

         diff --git a/AUTHORS b/AUTHORS
         index 293dd70..722c93e 100644
         --- a/AUTHORS
         +++ b/AUTHORS
         @@ -541,7 +541,7 @@ Lars Hecking                        <lhecking@nmrc.ucc.ie>
          Laszlo Molnar                  <laszlo.molnar@eth.ericsson.se>
          Leif Huhn                      <leif@hale.dkstat.com>
          Len Johnson                    <lenjay@ibm.net>
         -Leon Brocard                   <acme@astray.com>
         +Orange Brocard                 <acme@astray.com>
          Les Peters                     <lpeters@aol.net>
          Lesley Binks                   <lesley.binks@gmail.com>
          Lincoln D. Stein               <lstein@cshl.org>

       If you are a committer to Perl and you think the patch is
       good, you can then merge it into blead then push it out to
       the main repository:

         % git checkout blead
         % git merge experimental
         % git push

       If you want to delete your temporary branch, you may do so
       with:

         % git checkout blead
         % git branch -d experimental
         error: The branch 'experimental' is not an ancestor of your current HEAD.
         If you are sure you want to delete it, run 'git branch -D experimental'.
         % git branch -D experimental
         Deleted branch experimental.

CLEANING A WORKING DIRECTORY
       The command "git clean" can with varying arguments be used
       as a replacement for "make clean".

       To reset your working directory to a pristine condition
       you can do:

         git clean -dxf

       However, be aware this will delete ALL untracked content.
       You can use

         git clean -Xf

       to remove all ignored untracked files, such as build and
       test byproduct, but leave any  manually created files
       alone.

       If you only want to cancel some uncommitted edits, you can



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       use "git checkout" and give it a list of files to be
       reverted, or "git checkout -f" to revert them all.

       If you want to cancel one or several commits, you can use
       "git reset".

BISECTING
       "git" provides a built-in way to determine, with a binary
       search in the history, which commit should be blamed for
       introducing a given bug.

       Suppose that we have a script ~/testcase.pl that exits
       with 0 when some behaviour is correct, and with 1 when
       it's faulty. We need an helper script that automates
       building "perl" and running the testcase:

         % cat ~/run
         #!/bin/sh
         git clean -dxf
         # If you can use ccache, add -Dcc=ccache\ gcc -Dld=gcc to the Configure line
         sh Configure -des -Dusedevel -Doptimize="-g"
         test -f config.sh || exit 125
         # Correct makefile for newer GNU gcc
         perl -ni -we 'print unless /<(?:built-in|command)/' makefile x2p/makefile
         # if you just need miniperl, replace test_prep with miniperl
         make -j4 test_prep
         -x ./perl || exit 125
         ./perl -Ilib ~/testcase.pl
         ret=$?
         git clean -dxf
         exit $ret

       This script may return 125 to indicate that the
       corresponding commit should be skipped. Otherwise, it
       returns the status of ~/testcase.pl.

       We first enter in bisect mode with:

         % git bisect start

       For example, if the bug is present on "HEAD" but wasn't in
       5.10.0, "git" will learn about this when you enter:

         % git bisect bad
         % git bisect good perl-5.10.0
         Bisecting: 853 revisions left to test after this

       This results in checking out the median commit between
       "HEAD" and "perl-5.10.0". We can then run the bisecting
       process with:

         % git bisect run ~/run

       When the first bad commit is isolated, "git bisect" will



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       tell you so:

         ca4cfd28534303b82a216cfe83a1c80cbc3b9dc5 is first bad commit
         commit ca4cfd28534303b82a216cfe83a1c80cbc3b9dc5
         Author: Dave Mitchell <davem@fdisolutions.com>
         Date:   Sat Feb 9 14:56:23 2008 +0000

             [perl #49472] Attributes + Unknown Error
             ...

         bisect run success

       You can peek into the bisecting process with "git bisect
       log" and "git bisect visualize". "git bisect reset" will
       get you out of bisect mode.

       Please note that the first "good" state must be an
       ancestor of the first "bad" state. If you want to search
       for the commit that solved some bug, you have to negate
       your test case (i.e. exit with 1 if OK and 0 if not) and
       still mark the lower bound as "good" and the upper as
       "bad". The "first bad commit" has then to be understood as
       the "first commit where the bug is solved".

       "git help bisect" has much more information on how you can
       tweak your binary searches.

SUBMITTING A PATCH VIA GITHUB
       GitHub is a website that makes it easy to fork and publish
       projects with Git. First you should set up a GitHub
       account and log in.

       Perl's git repository is mirrored on GitHub at this page:

         http://github.com/github/perl/tree/blead

       Visit the page and click the "fork" button. This clones
       the Perl git repository for you and provides you with
       "Your Clone URL" from which you should clone:

         % git clone git@github.com:USERNAME/perl.git perl-github

       We shall make the same patch as above, creating a new
       branch:

         % cd perl-github
         % git remote add upstream git://github.com/github/perl.git
         % git pull upstream blead
         % git checkout -b orange
         % perl -pi -e 's{Leon Brocard}{Orange Brocard}' AUTHORS
         % git commit -a -m 'Rename Leon Brocard to Orange Brocard'
         % git push origin orange

       The orange branch has been pushed to GitHub, so you should



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       now send an email to perl5-porters@perl.org with a
       description of your changes and the following information:

         http://github.com/USERNAME/perl/tree/orange
         git@github.com:USERNAME/perl.git branch orange

MERGING FROM A BRANCH VIA GITHUB
       If someone has provided a branch via GitHub and you are a
       committer, you should use the following in your perl-ssh
       directory:

         % git remote add dandv git://github.com/dandv/perl.git
         % git fetch

       Now you can see the differences between the branch and
       blead:

         % git diff dandv/blead

       And you can see the commits:

         % git log dandv/blead

       If you approve of a specific commit, you can cherry pick
       it:

         % git cherry-pick 3adac458cb1c1d41af47fc66e67b49c8dec2323f

       Or you could just merge the whole branch if you like it
       all:

         % git merge dandv/blead

       And then push back to the repository:

         % git push

COMMITTING TO MAINTENANCE VERSIONS
       Maintenance versions should only be altered to add
       critical bug fixes.

       To commit to a maintenance version of perl, you need to
       create a local tracking branch:

         % git checkout --track -b maint-5.005 origin/maint-5.005

       This creates a local branch named "maint-5.005", which
       tracks the remote branch "origin/maint-5.005". Then you
       can pull, commit, merge and push as before.

       You can also cherry-pick commits from blead and another
       branch, by using the "git cherry-pick" command. It is
       recommended to use the -x option to "git cherry-pick" in
       order to record the SHA1 of the original commit in the new



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       commit message.

SEE ALSO
       The git documentation, accessible via "git help command".





















































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