doc/dev/refactoring-the-css-with-uiprops.rst
author Laurent Peuch <cortex@worlddomination.be>
Thu, 25 Jul 2019 03:33:01 +0200
changeset 12735 17d1b1f4eddd
parent 10492 68c13e0c0fc5
permissions -rw-r--r--
[cubicweb-ctl/fix] correctly get exception traceback_ for pdb.post_mortem In python 3 the behavior of sys.exc_info had a very subtle change: - in python 2 you can call if whenever you want after a try/except statement and you'll get information about this last raise - ipython 3, once you get out of try/except, sys.exc_info is cleaned and you'll get (None, None, None) Hardened the test to avoid this error from happening again.

=========================================
Refactoring the CSSs with UI properties
=========================================

Overview
=========

Managing styles progressively became difficult in CubicWeb. The
introduction of uiprops is an attempt to fix this problem.

The goal is to make it possible to use variables in our CSSs.

These variables are defined or computed in the uiprops.py python file
and inserted in the CSS using the Python string interpolation syntax.

A quick example, put in ``uiprops.py``::

  defaultBgColor = '#eee'

and in your css::

  body { background-color: %(defaultBgColor)s; }


The good practices are:

- define a variable in uiprops to avoid repetitions in the CSS
  (colors, borders, fonts, etc.)

- define a variable in uiprops when you need to compute values
  (compute a color palette, etc.)

The algorithm implemented in CubicWeb is the following:

- read uiprops file while walk up the chain of cube dependencies: if
  cube myblog depends on cube comment, the variables defined in myblog
  will have precedence over the ones in comment

- replace the %(varname)s in all the CSSs of all the cubes

Keep in mind that the browser will then interpret the CSSs and apply
the standard cascading mechanism.