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Developers/DevelopingCodeChanges – NEMO

Version 42 (modified by nicolasmartin, 7 years ago) (diff)


Developing code change

Last edition: Wikinfo(changed_ts)? by Wikinfo(changed_by)?


Until end of 2015, the PI if a given development action was expected to develop the code and its documentation in a development branch, to go through the different validation steps, and to submit it at the end to a reviewer, the positive answer of the review being a prerequisite for a merge into the NEMO reference.
Since Merge Party meeting end of 2015, the process has been changed to a more efficient and reliable process, in order to avoid disagreement and a lock at the review step. The sequence described below is presently to be followed for each development of the NEMO System Team's workplan.

A brief overview of the process is given below.

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Each development action is expected to be described in the yearly workplan including name of PI, and name(s) of {pre,re}viewer(s)

Merging back with the trunk is not described here.

Workplan content

The yearly workplan is discussed within System Team, submitted to Developer's Committee, and approved by Steering Committee. It must include, for each development action, its motivation, status, main tasks so as a PI name, and a previewer (which will also be the reviewer) name. If needed, previewer can be divided into a "Science Previewer" and a "System Previewer". The name of Previewer should be added only once he did accept the task, and before submission of workplan to Developer's Committee.

Detailed description of implementation plan and Preview step

Once the workplan has been approved, the code development is planned. The PI should create:

  • Associated wiki page for explanation. Please follow carefully the following indications:
    • Create review page from the root page of the yearly workplan wiki/${YEAR}WP
    • Once this last page is created, you do not need to edit it like a typical wiki page to complete the requested fields: just complete the fields in the writeable areas and click on "Submit" button at the end of the section to save your additions
    • Editing the page is only needed if your want to add some fields in the page. Activate the "side to side" button on top right of the page to facilitate this first edit and do not switch to 'wyziwig' view mode
    • The wiki page will describe:
      • Purpose, motivation and main tasks of the action
      • PI(S) & (P)Reviewer(s) name(s)
      • Detailed implementation plan: scientific, technical and an expected summary of changes for NEMO reference manual to be written later.
      • Detailed list of specific tests, see below
      • (P)Review status

This page will permit to follow the ongoing work through different steps and will go with:

  • A linked ticket to gather the group discussion. The following fields have to be set in a appropriate way:
    • 'Cc': (P)Reviewer(s) and possible follower(s) should be added for further email notification.
    • 'Component': the area the change is being targeted for.
    • 'Type': 'development branch'
    • 'Owner': the code developer

The other fields in the !ticket (e.g. 'Priority', 'Milestone', 'Keywords') should also be set appropriately.

Once the wiki page is completed by PI (detailed implementation plan), the PI will submit it to Previewer. The Previewer will discuss with PI to reach full agreement on detailed implementation plan (in a maximum of 2 weeks starting when PI submits wiki page to Previewer).
The PI is responsible to give all requested details.
The Previewer is responsible to check with all experts that implementation plan is indeed correct and compatible with the other developments going on in parallel during the year. Objective is to avoid the need for a full rewriting at the end (which did happen sometimes previously)

Start the coding

Once the Previewer has sent the green light (approval of detailed implementation plan and summary of changes in reference manual), the PI can created the corresponding development branch. The branch should be created from the up to date version of NEMO as chosen for each year (usually the trunk at a give fixed revision for a give year, see minutes of NEMO System Team videoconferences. Development can progress on this new branch.

Each year, development branches will be created in the directory svn/nemo/branches/YEAR/"standard name of dev branch".
"standard name of dev branch" should be: dev_"starting revision number"_"workplan item_purpose" (ex 'dev_r1302_LOCEAN1_mpp')

Develop your Change

A few things to bear in mind when developing your changes,

  • Follow the appropriate coding standard, see NEMO coding standards document.
  • Ensure commit messages to your branch are meaningful. They are visible to everyone using the system.
  • You don't have to commit to your branch to test a change. You can compile from a working copy.

Test your Change

Test your change appropriately and record the results. The testing required will depend on the change and the potential impact on other configurations. When testing, things to consider include

  • full successful SETTE tests: to check nothing is broken or goes wrong in the reference configurations SETTE tests: if running with some changes in the results, those have to be justified and checked in detail. New code should not change results when it is switched off, and not alter results when tuned on.
  • full successful specific tests: to be defined before starting, in order to check that development does indeed what is expected

In particular the Trusting tool has been developed in order to ease the validation all along the working on the code, not all in one with SETTE. The developer can regularly evaluate the changes for a any given configuration compared with benchmark results he has defined.

Document your Change

  • Progress in the development should be documented as the work goes on in the !ticket created at the beginning/
  • Code should be documented on line as defined in the coding rules
  • Changes in the reference manual should be also written as soon as possible, and before review process


Once your development is completed, PI requests work of Reviewer(s) for scientific or technical correctness.

The reviewer should check that th development did indeed meet what has been approved at Preview step

  • The code changes are understood and appropriately made.
  • The documentation is sufficient to understand the code change and its impacts.

The Reviewers completes the review part of wiki page with the PI. Once all light are green, the development is approved and can be merged for the new release of NEMO.