Mercurial

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

Everybody is free to run, copy, distribute, study, change and improve Octave's source code, given in the main repository at https://www.octave.org/hg/octave. Use Mercurial to get the latest version of Octave

hg clone https://www.octave.org/hg/octave

TortoiseHg is a GUI for Mercurial and it is especially recommended for users doing their first steps with source code management systems. Linux, macOS, and MS Windows are supported.

Creating and submitting patches (changesets)

If you want to share your modifications, for example to fix a nasty bug #42424, you cannot just submit your changes to Octave's main repository. You have to generate a patch (or changeset) so other Octave developers can include them into Octave's source code.

1. Get the latest version 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 bug #42424) and save them. Make sure that your changes don't introduce new bugs! Thus it is recommended to build Octave and to run Octave's test suite before proceeding.
   
   

   Please follow the Contribution guidelines for C/C++ or Octave code files!
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 what you changed to display relevant topics
     first.  The maximal line width is 80 characters.
   

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 Summer of Code students working on new Octave features.

Students should publish their work as it progresses in a public repository. In this section we use for example public.server.org/octave.

Using bookmarks

Bookmarks are useful for identifying a series of commits. They are a "lightweight" solution to named branches, which are not automatically updated for example. To create a bookmark my-gsoc use

hg clone https://www.octave.org/hg/octave
hg bookmark my-gsoc

To make the bookmark visible in the public repository use

hg push --bookmark ssh://student@public.server.org/octave

Staying up-to-date with the main repository

Octave development does not stand still while the students development proceeds. Octave's main repository gets updated, too. The following commands can be used to get these updated to the students clone of the main repository:

hg pull https://www.octave.org/hg/octave   # Get latest remote "tip"
hg update -r my-gsoc                       # Activate bookmark "my-gsoc"
hg merge tip                               # Merge  "tip" into "my-gsoc"
hg commit -m "maint: merge default to my-gsoc"
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 repository.

1. Create a full log of changes

   hg log --template=changelog --no-merges --user student-name

   If students have been following the Commit message guidelines the output is a good starting point for the commit message in the next step. Some manual post-processing might be necessary:
   • Each touched file should appear only once.
   • Do not mention backed-out commits.
2. Prepare a singe patch (changeset) including all code that should be submitted for review

   hg pull https://www.octave.org/hg/octave   # Get remote "tip" and "@"
   hg update -r @                             # Activate    bookmark "@"
   hg merge my-gsoc                           # Merge "my-gsoc" into "@"
   hg commit
   hg export -r tip -o mid-term-review.patch
   

   The file mid-term-review.patch can uploaded to the patch tracker.
   Finally, there is a subtle difference between "tip", which is a reference to the (local or remote) changeset added to the repository most recently and the bookmark "@" used by the Octave developers to point to the latest remote changeset. Often both refer to the very same changeset and they can used interchangeably.

Example Mercurial configuration

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

External links

• https://hginit.com/ -- Mercurial tutorial
• https://www.mercurial-scm.org/wiki/Tutorial -- Mercurial tutorial
• https://www.mercurial-scm.org/wiki/QuickStart -- Mercurial quick start
• https://tortoisehg.bitbucket.io/ -- TortoiseHg is a GUI for Mercurial (Linux, macOS, MS Windows)