Developing Roundup — Roundup 2.5.0 documentation
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# Developing Roundup

Note

The intended audience of this document is the developers of the core Roundup code. If you just wish to alter some behavior of your Roundup installation, see Customising Roundup.

Contents

## Getting Started

If you are looking for a good first issue, search for StarterTicket on https://issues.roundup-tracker.org. These include issues where Python development, documentation or web design skills are useful.

You can continue the conversation using the issue or join the Roundup-devel list to get assistance and verify your planned changes.

All development is coordinated through two resources:

- roundup-devel mailing list at https://sourceforge.net/projects/roundup/lists/roundup-devel

- The issue tracker running at https://issues.roundup-tracker.org/

In addition, the Roundup IRC channel on irc.oftc.net can be accessed via the web interface shown on the Contact page. The channel is logged and the web sites for the logs are shown in the channel topic. You can ask questions and use it to coordinate work discussed using the resources above.

Anyone wishing to help in the development of the Roundup Python core may find Roundup’s Design Document and the implementation notes helpful.

People working on Documentation or designing changes to the Web interface don’t need to get into the implementation internals.

## Project Rules

Be polite to others. There is no place for ad hominem attacks.

Mostly the project follows Guido’s Python Style (though naming tends to be a little relaxed sometimes). In short:

- 80 column width code

- 4-space indentations

Other project rules:

- new functionality must be documented, even briefly (so at least we know where there’s missing documentation) and changes to tracker configuration must be logged in the upgrading document.

- discuss any changes with the other developers on roundup-dev. If nothing else, this makes sure there’s no rude shocks.

- write unit tests for changes you make (where possible), and ensure that all unit tests run before committing changes.

- run flake8 or pylint over changed code.

- if you have direct commit access to the repository, subscribe to roundup-checkins to receive checkin notifications from the other developers with write access to the source-code repository.

The goal is to have no flake8 issues. Current code has complex functions, some long lines and use of mutable objects in function signatures. Some third party code (e.g. ZPT) vendored into the codebase has more issues.

The administrators of the project reserve the right to boot developers who consistently check in code which is either broken or takes the codebase in directions that have not been agreed to.

## Setting up a Development Environment

Roundup doesn’t require any external libraries. Installing Python 3 and its core libraries is enough to get Roundup running.

The easiest way to work with Roundup is to clone the repository. Roundup is developed using the Mercurial distributed version control system (DVCS) [1]. It is hosted at Sourceforge. See https://www.roundup-tracker.org/code.html for details.

If you are used to git, Mercurial’s command equivalence table can help. Most of the concepts from git (except for staging) should be familiar.

To clone the repository use:

    hg clone http://hg.code.sf.net/p/roundup/code roundup

(Yes, that is an http url.)

This will create a read only clone (you can’t `hg push`) of the repo. Changes you make can be attached as patches (created using `hg diff`) to tickets in our issue tracker.

See https://www.roundup-tracker.org/code.html for URL’s and directions on getting read write access which allows pushing to the repository.

Once you have your clone, you can run `python3 ./demo -b sqlite` and get a working Roundup server. This will start the server using the `sqlite` backend. The code is in the `roundup` subdirectory.

To test internationalization in your environment, you have to process the locale sub-directory into a form that roundup’s i18n code will recognize. To do this use:

> make -C locale local_install

which will compile the `.po` source files into binary `.mo` files and install them under `locale/locale/<LANGUAGE_CODE>/LC_MESSAGES/roundup.mo`. For German this will be `locale/locale/de/LC_MESSAGES/roundup.mo`.

By default this requires `msgfmt` from the the GNU gettext tools installed on your system. If you do not have `msgfmt` installed, you can use:

> make -C locale local_install MSGFMT=”python3 ../roundup/msgfmt.py”

Also to compile a single .po file, you can invoke `python roundup/msgfmt.py po_file mo_file` to compile your .po file to a .mo file. It’s slow but seems to work in basic tests. The msgfmt.py file is used by Roundup to compile out of date .po files.

## Submitting Changes

Most small changes can be submitted as patches through the issue tracker or sent to Roundup-devel mailing list.

Your account on sourceforge can be set up to allow direct pushes to the repo. Once that is done, using:

    hg push https://user@hg.code.sf.net/p/roundup/code

or

> hg push ssh://user@hg.code.sf.net/p/roundup/code

will commit your changes.

## Other Resources - CI, Code Coverage

Roundup has a copy of the mercurial repository on GitHub. It is updated manually after every few commits to the Mercurial repository. Updates trigger the CI pipeline which happens on two services:

> 1. GitHub Actions. It runs Docker container scans using Anchore as well as security scans for dependencies using CodeQL. Also it runs the test suite on multiple versions of Python.

> 2. TravisCI is also used to run CI. It runs the test suite on multiple Python versions. It also provides alpha and development Python releases faster than GitHub.

GitHub actions upload coverage statistics to both CodeCov and Coveralls. TravisCI only uploads to CodeCov.

We run our own issue tracker so we can dogfood the code. As a result, we do not use GitHub issues. Pull requests are grudgingly accepted. They have to be exported and applied to the Mercurial repository. This is time consuming so patches attached to an issue in our tracker are preferred.

## Debugging Aids

Try turning on logging of DEBUG level messages. This may be done a number of ways, depending on what it is you’re testing:

1. If you’re testing the database unit tests, then set the environment variable `LOGGING_LEVEL=DEBUG`. This may be done like so:

   > LOGGING_LEVEL=DEBUG python -m pytest test/

   This variable replaces the older HYPERDBDEBUG environment var.

2. If you’re testing a particular tracker, then set the logging level in your tracker’s `config.ini`.

If you set the environment variable SENDMAILDEBUG to a filename, roundup will write each email message that it sends to that file instead to the internet. This environment variable is independent of the python -O flag.

## Documentation Notes

All docs are written using sphinx. Use pip or your package manager to install sphinx. In addition you will need to install a couple of sphinx extensions to process the files. A requirement’s file can be found in docs/requirement.pip or website/www/requirements.pip. You can install these requirements using `python -m pip install -r <path_to_requirements_file>`.

The extensions sphinx-sitemap generates a sitemap when building for the website. The sphinx-tabs extension generates tabs for displaying code examples in both TAL and Jinja2.

To build the documentation distributed with a Roundup release, run `python setup.py build_doc` at the root of the source tree. To build docs for the website, see the `updating www.roundup-tracker.org` section of `website/README.txt` or TL;DR `cd website/www; make html`.

## Testing Notes

Create tests for your changes. Also run the tests in reverse to try to identify test dependencies. You can do this by creating a `conftest.py` in the top of the source tree and include the following contents:

    def pytest_collection_modifyitems(items):
        items.reverse()

to run all the tests in reverse. More tips at: https://testmon.org/blog/hidden-test-dependencies/.

The full test suite can take a while to run. The pytest-testmon package can be installed with pip. It analyzes changes to code and run tests that test that code. This can significantly reduce the time it takes to run a basic test suite. Use it by running:

    python3 -m pytest -v --testmon test

once over the whole test suite. Then subsequent calls will analyze the changed files/functions and run tests that cover those changes.

To run some tests (test_liveserver.py, test_indexer.py, …) you need to have some additional modules installed. These include:

> - requests

> - mock

If you are working with a docker container that is set up to execute Python application and not for development, you will need to install pytest.

## Internationalization Notes

How stuff works:

1. Strings that may require translation (messages in human language) are marked in the source code. This step is discussed in Marking Strings for Translation section.

2. These strings are all extracted into Message Template File `locale/roundup.pot` (POT file). See Extracting Translatable Messages below.

3. Language teams use POT file to make Message Files for national languages (PO files). All PO files for Roundup are kept in the `locale` directory. Names of these files are target locale names, usually just 2-letter language codes. Translating Messages section of this chapter gives useful hints for message translators.

4. Translated Message Files are compiled into binary form (MO files) and stored in `locale` directory (but not kept in the source code repository, as they may be easily made from PO files). See Compiling Message Catalogs section.

5. Roundup installer creates runtime locale structure on the file system, putting MO files in their appropriate places.

6. Runtime internationalization (I18N) services use these MO files to translate program messages into language selected by current Roundup user. Roundup command line interface uses locale name set in OS environment variable `LANGUAGE`, `LC_ALL`, `LC_MESSAGES`, or `LANG` (in that order). Roundup Web User Interface uses language selected by currently authenticated user.

Additional details may be found in GNU gettext and Python gettext module documentation. Additional information on `.po` translation files can also be found at pology.

Roundup source distribution includes POT and PO files for message translators, and also pre-built MO files to facilitate installations from source. Roundup binary distribution includes MO files only.

### GNU gettext package

This chapter is full of references to GNU gettext package. GNU gettext is a “must have” for nearly all steps of internationalizing any program, and it’s manual is definitely a recommended reading for people involved in I18N.

There are GNU gettext ports to all major OS platforms. Windows binaries are available from GNU mirror sites.

Roundup does not use GNU gettext at runtime, but it’s tools are used for extracting translatable messages, compiling message catalogs and, optionally, for translating messages.

Note that `gettext` package in some OS distributions means just runtime tools and libraries. In such cases gettext development tools are usually distributed in separate package named `gettext-devel`.

### Marking Strings for Translation

Strings that need translation must be marked in the source code. Following subsections explain how this is done in different cases.

If translatable string is used as a format string, it is recommended to always use named format specifiers:

    _('Index of %(classname)s') % locals()

This helps translators to better understand the context of the message and, with Python formatting, remove format specifier altogether (which is sometimes useful, especially in singular cases of Plural Forms).

When there is more than one format specifier in the translatable format string, named format specifiers must be used almost always, because translation may require different order of items.

It is better to not mark for translation strings that are not locale-dependent, as this makes it more difficult to keep track of translation completeness. For example, string `</ol></body></html>` (in `index()` method of the request handler in `roundup_server` script) has no human readable parts at all, and needs no translations. Such strings are left untranslated in PO files, and are reported as such by PO status checkers (e.g. `msgfmt --statistics`).

Hints for the translator can be added by adding a comment block starting with `# .Hint`. The hints will be extracted into the .pot file and merged to the .po files used by the translators. This can add context to how the string is used. For example from admin.py:

    # .Hint read as: assignedto was admin(1)
    # where assignedto is the property
    # admin is the key name for value 1
    _("%(prop)s was %(name)s(%(value)s)")

is shown in the .po file as:

    #. .Hint read as: assignedto was admin(1)
    #. where assignedto is the property
    #. admin is the key name for value 1
    #: ../roundup/admin.py:1091
    #, python-format
    msgid "%(prop)s was %(name)s(%(value)s)"
    msgstr ""

allowing the translator to see the replaced string so they can understand how name and value are used.

### Command Line Interfaces

Scripts and routines run from the command line use “static” language defined by environment variables recognized by `gettext` module from Python library (`LANGUAGE`, `LC_ALL`, `LC_MESSAGES`, and `LANG`). Primarily, these are `roundup-admin` script and `admin.py` module, but also help texts and startup error messages in other scripts and their supporting modules.

For these interfaces, Python `gettext` engine must be initialized to use Roundup message catalogs. This is normally done by including the following line in the module imports:

    from i18n import _, ngettext

Simple translations are automatically marked by calls to builtin message translation function `_()`:

    print(_("This message is translated"))

Translations for messages whose grammatical depends on a number must be done by `ngettext()` function:

    print(ngettext("Nuked %i file", "Nuked %i files", number_of_files_nuked))

### Deferred Translations

Sometimes translatable strings appear in the source code in untranslated form [3] and must be translated elsewhere. Example:

    for meal in ("spam", "egg", "bacon"):
        print(_(meal))

In such cases, strings must be marked for translation without actual call to the translating function. To mark these strings, we use Python feature of automatic concatenation of adjacent strings and different types of string quotes:

    strings_to_translate = (
        ''"This string will be translated",
        ""'me too',
        ''r"\raw string",
        ''"""
        multiline string"""
    )

[3]

In current Roundup sources, this feature is extensively used in the `admin` module using method docstrings as help messages.

### Web User Interface

For Web User Interface, translation services are provided by Client object. Action classes have methods `_()` and `gettext()`, delegating translation to the Client instance. In HTML templates, translator object is available as context variable `i18n`.

HTML templates have special markup for translatable strings. The syntax for this markup is discussed at ZPTInternationalization. (Originally documented at http://dev.zope.org/Wikis/DevSite/Projects/ComponentArchitecture/ZPTInternationalizationSupport which is now gone.) Roundup translation service currently ignores values for `i18n:domain`, `i18n:source` and `i18n:target`.

Template markup examples:

- simplest case:

      <div i18n:translate="">
       Say
       no
       more!
      </div>

  this will result in msgid `"Say no more!"`, with all leading and trailing whitespace stripped, and inner blanks replaced with single space character.

- using variable slots:

      <div i18n:translate="">
       And now...<br/>
       No.<span tal:replace="number" i18n:name="slideNo" /><br/>
       THE LARCH
      </div>

  Msgid will be: `"And now...<br /> No.${slideNo}<br /> THE LARCH"`. Template rendering will use context variable `number` (you may use any expression) to put instead of `${slideNo}` in translation.

- attribute translation:

      <button name="btn_wink" value=" Wink " i18n:attributes="value" />

  will translate the caption (and return value) for the “wink” button.

- explicit msgids. Sometimes it may be useful to specify msgid for the element translation explicitly, like this:

      <span i18n:translate="know what i mean?">this text is ignored</span>

  When rendered, element contents will be replaced by translation of the string specified in `i18n:translate` attribute.

- `i18n` in TALES. You may translate strings in TALES python expressions:

      <span tal:replace="python: i18n.gettext('Oh, wicked.')" />

- plural forms. There is no markup for plural forms in TAL i18n. You must use python expression for that:

      <span tal:replace="python: i18n.ngettext(
        'Oh but it\'s only %i shilling.',
        'Oh but it\'s only %i shillings.',
        fine) % fine"
      />

#### Detectors and extensions

The correct `i18n` objects gets automatically injected in the hyperdb. In a detector you can access the i18n object and do translation like this:

    def statusfail(db, cl, nodeid, newvalues):
      _ = db.i18n.gettext
      raise ValueError(_("this does not work"))

    def init(db):
      # fire before changes are made
      db.status.audit('create', statusfail)

#### Extracting Translatable Messages

The most common tool for message extraction is `xgettext` utility from GNU gettext package. Unfortunately, this utility has no means of Deferred Translations in Python sources. There is `xpot` tool from Francois Pinard free PO utilities that allows to mark strings for deferred translations, but it does not handle plural forms.

Roundup overcomes these limitations by using both of these utilities. This means that you need both GNU gettext tools and PO utilities to build the Message Template File yourself.

Latest Message Template File is kept in the source code repository and distributed with Roundup Source. If you wish to rebuild the template yourself, make sure that you have both `xpot` and `xgettext` installed and just run `gmake` (or `make`, if you are on a GNU system like linux or cygwin) in the `locale` directory.

For on-site i18n, Roundup provides command-line utility:

    roundup-gettext <tracker_home>

extracting translatable messages from tracker’s html templates and detectors / extensions (assuming polib is installed) [2]. This utility creates message template file `messages.pot` in `locale` subdirectory of the tracker home directory. Translated messages may be put in locale.po files (where locale is the two character locale name) in the same directory, e.g.: `locale/ru.po`. These message catalogs are searched prior to system-wide translations kept in the `share` directory.

If you are creating your own `.po` file from scratch rather than using `roundup-gettext`, you must have the minimal preamble specifying the format of the file. This:

    msgid ""
    msgstr ""
    "Content-Type: text/plain; charset=UTF-8\n"

should be present as the first translatable string in your .po file. If you use `roundup-gettext` it will add a full preamble including `Content-Type`. If the preamble is missing, using characters outside of the ASCII range will cause Roundup to crash with a UnicodeDecodeError.

[2]

Note that it will not extract deferred translations from detectors or extensions. Those have to be manually added to messages.pot.

#### Translating Messages

Gettext Message File (PO file) is a plain text file, that can be created by simple copying `roundup.pot` to new .po file, like this:

    $ cp roundup.pot ru.po

The name of PO file is target locale name, usually just 2-letter language code (`ru` for Russian in the above example). Alternatively, PO file may be initialized by `msginit` utility from GNU gettext tools:

    $ msginit -i roundup.pot

`msginit` will check your current locale, and initialize the header entry, setting language name, rules for plural forms and, if available, translator’s name and email address. The name for PO file is also chosen based on current locale.

Next, you will need to edit this file, filling all `msgstr` lines with translations of the above `msgid` entries. PO file is a plain text file that can be edited with any text editor. However, there are several tools that may help you with this process:

> - poEdit by Vaclav Slavik. Very nice cross-platform GUI editor.

> - Lokalize. A replacement for KBabel. Being part of KDE, it works in X windows only. Haven’t had much experience with it, though.

> - `po-mode` for emacs. One of GNU gettext tools. Very handy, definitely recommended if you are comfortable with emacs. Cannot handle plural forms per se, but allows to edit them in simple text mode.

> - po filetype plugin for vim. Does not do as much as `po-mode`, but helps in finding untranslated and fuzzy strings, and checking code references. Please contact alexander smishlajev if you prefer this, as i have patched this plugin a bit. I have also informed the original plugin author about these changes, but got no reply so far.

Additional information on `.po` files can be found at pology.

#### Compiling Message Catalogs

Message catalogs (PO files) must be compiled into binary form (MO files) before they can be used in the application. This compilation is handled by `msgfmt` utility from GNU gettext tools. `GNUmakefile` in the `locale` directory automatically compiles all existing message catalogs after updating them from Roundup source files. If you wish to rebuild an individual MO file without making everything else, you may, for example:

    $ msgfmt --statistics -o ru.mo ru.po

This way, message translators can check their PO files without extracting strings from source. (Note: String extraction requires additional utility that is not part of GNU gettext. See Extracting Translatable Messages.)

At run time, Roundup automatically compiles message catalogs whenever PO file is changed.

[1]

Roundup is written in Python and we believe in using tools in the Python ecosystem whenever possible.

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