Mercurial

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Mercurial (sometimes referred to as hg) is the source code management system used for Octave development.

Contributing to Octave

The preferred method to contribute to Octave is with Mercurial changesets. Other forms of contributions (e.g., simple diff patches) are also acceptable, but they slow down the review process.

If you plan on contributing to Octave:

Creating and submitting patches (changesets)

If you want to modify Octave's source code, given at https://www.octave.org/hg/octave, you cannot just submit your changes there. You have to generate a patch (or changeset) so Octave developers with permissions can include them into Octave's source code.

  1. Get the latest revision of Octave (or some Octave package)
    hg clone https://www.octave.org/hg/octave
    or when already cloned
    hg pull && hg update
  2. Make your changes (fix the bug) and save them.
  3. Commit your changes
    hg commit
    Mercurial will open your default editor and ask you for a commit message. Please follow the commit message guidelines, e.g.
    help.m: Display relevant topics first (bug #42424)
    
    * scripts/help/help.m: Describe how to display relevant topics first.
    
  4. Export the changes
    hg export -r tip -o bug42424.patch
    The final patch for submission will look like this
  5. Upload bug42424.patch to the bug or patch tracker. If your patch file is larger than the upload limit, you can compress it before uploading. Please use a free format!

Mercurial Tips for SoC students

This section is meant to provide tips for SOCIS or GSoC students working on new Octave features.

Students should publish their work as it progresses in a public repository merging regularly the main savannah repository to facilitate merging back their code at the end of the project.

Here are some useful hg commands that can be used to do this.

Getting started

  1. Clone the main Octave repository at savannah:
    hg clone http://www.octave.org/hg/octave
  2. Create a new bookmark:
    hg bookmark student-bookmark-name
  3. Make the bookmark visible in the public repo, assuming the public repo is at public.server.org/octave
    hg push --bookmark ssh://student@public.server.org/octave

Staying up-to-date with the main savannah repository

As the students development proceeds, the savannah repository gets updated, too. To avoid having the two branches diverging too much, which can lead to conflicts when the final merge is done, students should keep their public repo up-to-date with the recent changes, the following commands can be used for this:

  1. Download new changes from the main line of development
    hg pull http://www.octave.org/hg/octave
  2. Merge the main line of development into the feature branch
    hg up -r student-bookmark-name
    hg merge @
  3. Apply the change and publish it
    hg commit -m "periodic merge of default branch into my branch"
    hg push ssh://student@public.server.org/octave

Preparing for code reviews

At the time of the mid-term or final review (or whenever the mentor requires it) students should prepare their code for review and possibly inclusion into the main development branch. To this end students should:

  1. prepare a full log of their changes, listing files that have been touched and including a summary of the purpose of those changes. If students have been following the Commit message guidelines the following command will give a good starting point
    hg log --style=changelog --no-merges --user student-name
    this message should be edited so that
    1. each touched file appears only once
    2. changes that were backed out should not be mentioned

    The main purpose of this log is to make it easy, not only for the main mentor, but also for other developers who have not been closely following the progress of the project to quickly understand where to look at in the code to evaluate it, but it will also be used as the commit message for the merge changeset, so it should itself comply with the Commit message guidelines.

  2. prepare a merge changeset including all the code that should be submitted for review
    1. pull from the main repository
      hg pull http://www.octave.org/hg/octave
    2. move to the top of the main line of development and merge in the feature branch
      hg up -r @
      hg merge student-bookmark-name
    3. create a changeset, export it and send to the mentor for review, remember to use the log created above as a commit message
      hg commit
      hg export @ > mid-term-review.changeset
      the file mid-term-review.changeset can then be sent to the mailing list or posted to the patch tracker

Example Mercurial configuration

Place the following file in your home directory, e.g. /home/username/.hgrc.

File: .hgrc
[ui]
username = Your Name <your@email>

[extensions]
color =
histedit =
pager =
rebase =
strip =

[pager]
pager = LESS='FSRX' less
attend = help, annotate, cat, diff, export, glog, log, outgoing, incoming

[diff]
showfunc = True

[color]
mode = terminfo

## Custom colors
color.gray = 244
color.orange = 202
color.lightyellow = 191
color.darkorange = 220
color.brightyellow = 226

status.modified = magenta bold
status.added = green bold
status.removed = red bold
status.deleted = cyan bold
status.unknown = gray bold
status.ignored = gray bold

## Colours for each label
log.branch = cyan
log.summary = lightyellow
log.description = lightyellow
log.bookmark = green
log.tag = darkorange
log.graph = blue

## Colors for each phase
changeset.secret = blue bold
changeset.draft  = red bold
changeset.public = orange

desc.here = bold blue_background

[bookmarks]
track.current = True

[alias]
glog = log --graph
top = log --graph -l

External links