Changeset 5955 for main/waeup.sirp/trunk/src/waeup/sirp

Timestamp:

22 Apr 2011, 01:35:13 (14 years ago)

Author:

uli

Message:

Add a source for themes (aka skins) and show how to make use of the
ZCA to make things extendible in third-party packages.

This is the first step in an effort to provide clean and extendible
themes with waeup.sirp.

'clean' means: it was not clean yet to hardcode CSS file names (which
should be business of the browser subpackage) in the central
interfaces definitions file waeup.sirp.interfaces.

It was also not too clean, that we

It was also impossible for extension packages to define new own themes
yet or extend existing themes by adding some CSS file.

'extendible' means: with the new theme-source and theme-provider we
define clearly, what interface we expect from another package (for
instance the browser subpackage or any third-party package) to
retrieve a list of available themes at all. This list is then used by
the manage-view of University instances to provide a list of themes to
select for all pages.

The browser subpackage will also provide a theme-provider that looks
up all themes defined somewhere (in waeup.sirp _and_ other packags) at
runtime.

File:

• main/waeup.sirp/trunk/src/waeup/sirp/interfaces.py (modified) (3 diffs)

main/waeup.sirp/trunk/src/waeup/sirp/interfaces.py

@@ -9 +9 @@
     # BBB
     from zope.app.catalog.interfaces import ICatalog
-from zope.interface import Interface, Attribute
+from zope.interface import Interface, Attribute, implements
 from zope import schema
 from zope.schema.vocabulary import SimpleVocabulary, SimpleTerm
 from waeup.sirp.permissions import RoleSource
 
+class IThemeProvider(Interface):
+    """A component that delivers all themes defined.
+
+    We normally do not deal with browser-related stuff in `waeup.sirp`
+    but leave that to the `browser` subpackage. With themes (aka
+    skins) we cannot follow that path because we need a theme as an
+    attribute of each `University` instance.
+
+    Therefore we must tell the browser subpackage how we expect themes
+    to be announced code-wise.
+
+    What we tell here is that we might ask for a utility providing
+    IThemeProvider and that this component then should be callable to
+    give us a list of themes and their respective internal names.
+    """
+    def __call__():
+        """Get a list of all themes available.
+
+        Returns a list of ``(<NAME>, <THEME>)`` tuples where
+        ``<NAME>`` is the internal name under which a theme was
+        registered and ``<THEME>`` is the real theme.
+        """
+
+class ThemeSource(BasicSourceFactory):
+    """A source for themes.
+    """
+    def getValues(self):
+        """Get names of themes.
+        """
+        theme_provider = getUtility(IThemeProvider, name="default")
+        return [x for x, y in theme_provider()]
+    
+    def getTitle(self, value):
+        """Get a user-presentable description for a theme.
+        """
+        theme_provider = getUtility(IThemeProvider, name="default")
+        for name, theme in theme_provider():
+            if name == value:
+                return theme.description
+        return u'unnamed'
+
+class ThemeSourceBinder(object):
+    """A source binder for the `ThemeSource`.
+
+    Normally, we can pass instances of a source (like `ThemeSource`)
+    directly to fields in interfaces (writing something like ``source
+    = ThemeSource()``. With `ThemeSource` we cannot do this, because
+    the set of available themes is not available before the whole
+    `waeup.sirp` package was grokked (and parsed).
+
+    We bypass that problem by defining this trivial source-binder,
+    which is asked for themes only when the values of the source are
+    really needed and after the process of grokking and parsing
+    everything on startup.
+
+    So, although this binder binds to some context (`IUniversity` is
+    currently the only interface making use of this source, so
+    `University` instances are the only context used), the context
+    does not really matter.
+    """
+    implements(schema.interfaces.IContextSourceBinder)
+
+    def __call__(self, context):
+        return ThemeSource()
+
 class FatalCSVError(Exception):
     """Some row could not be processed.
@@ -26 +91 @@
             SimpleTerm(value, value, title) for title, value in terms])
 
+
 class IWAeUPObject(Interface):
     """A WAeUP object.
@@ -40 +106 @@
         required = True,
         )
-    
+
+        
     skin = schema.Choice(
         title = u'Skin',
         default = u'waeuptheme-gray1.css',
-        #values = ['waeuptheme-gray1.css', 'waeuptheme-red1.css'],
-        vocabulary = SimpleWAeUPVocabulary(
-            ('Henrik\'s Gray Theme', 'waeuptheme-gray1.css'), ('Uli\'s Red Theme', 'waeuptheme-red1.css')),
+        source = ThemeSourceBinder(),
         required = True,
         )