Coding guidelines

-----------------

We don't have a formal coding/formatting standard. We are currently using a mix

of Mercurial's (https://www.mercurial-scm.org/wiki/CodingStyle), pep8, and

consistency with existing code. Run ``scripts/run-all-cleanup`` before

committing to ensure some basic code formatting consistency.

We support Python 3.6 and later.

We try to support the most common modern web browsers. IE9 is still supported

to the extent it is feasible, IE8 is not.

We primarily support Linux and OS X on the server side but Windows should also work.

HTML templates should use 2 spaces for indentation ... but be pragmatic. We

should use templates cleverly and avoid duplication. We should use reasonable

semantic markup with element classes and IDs that can be used for styling and testing.

We should only use inline styles in places where it really is semantic (such as

``display: none``).

JavaScript must use ``;`` between/after statements. Indentation 4 spaces. Inline

multiline functions should be indented two levels -- one for the ``()`` and one for

``{}``.

Variables holding jQuery objects should be named with a leading ``$``.

Commit messages should have a leading short line summarizing the changes. For

bug fixes, put ``(Issue #123)`` at the end of this line.

Use American English grammar and spelling overall. Use `English title case`_ for

page titles, button labels, headers, and 'labels' for fields in forms.

.. _English title case: https://en.wikipedia.org/wiki/Capitalization#Title_case

Template helpers (that is, everything in ``kallithea.lib.helpers``)

should only be referenced from templates. If you need to call a

helper from the Python code, consider moving the function somewhere

else (e.g. to the model).

Notes on the SQLAlchemy session

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Each HTTP request runs inside an independent SQLAlchemy session (as well

as in an independent database transaction). ``Session`` is the session manager

and factory. ``Session()`` will create a new session on-demand or return the

current session for the active thread. Many database operations are methods on

Database model objects

(almost) always belong to a particular SQLAlchemy session, which means

that SQLAlchemy will ensure that they're kept in sync with the database

(but also means that they cannot be shared across requests).

Objects can be added to the session using ``Session().add``, but this is

rarely needed:

* When creating a database object by calling the constructor directly,

  it must explicitly be added to the session.

* When creating an object using a factory function (like

  ``create_repo``), the returned object has already (by convention)

  been added to the session, and should not be added again.

* When getting an object from the session (via ``Session().query`` or

  any of the utility functions that look up objects in the database),

  it's already part of the session, and should not be added again.

  SQLAlchemy monitors attribute modifications automatically for all

  objects it knows about and syncs them to the database.

SQLAlchemy also flushes changes to the database automatically; manually

calling ``Session().flush`` is usually only necessary when the Python

code needs the database to assign an "auto-increment" primary key ID to

a freshly created model object (before flushing, the ID attribute will

be ``None``).

TurboGears2 DebugBar

^^^^^^^^^^^^^^^^^^^^

It is possible to enable the TurboGears2-provided DebugBar_, a toolbar overlayed

over the Kallithea web interface, allowing you to see:

* timing information of the current request, including profiling information

* request data, including GET data, POST data, cookies, headers and environment

  variables

* a list of executed database queries, including timing and result values

DebugBar is only activated when ``debug = true`` is set in the configuration

file. This is important, because the DebugBar toolbar will be visible for all

users, and allow them to see information they should not be allowed to see. Like

is anyway the case for ``debug = true``, do not use this in production!

To enable DebugBar, install ``tgext.debugbar`` and ``kajiki`` (typically via

``pip``) and restart Kallithea (in debug mode).