cornerstone.cssvar 1.0

This is an implementation of a CSS Variables extension for Zope Browser Resources.

Cascading Stylesheets don’t have any built in method to define variables and use them within the stylesheet. This feature was discussed at some CSS related blogs already and resulted in a non-official draft specification.

In former Zope versions DTML templating language was used to define variables in CSS. This breaks CSS syntax, looks crappy and produces error messages in CSS-enabled editors even if the browser gets the correct values.

cornerstone.cssvar uses an almost CSS syntax compatible variant to apply variables:

div.foo {
    color: var(myColor);
}

If we declare such a css resource using zcml it looks this way:

<browser:cssvarResource
  name="foo"
  file="foo.css"
/>

If we use the common mechanism to declare variables using css like syntax we must do this in a separate file, this looks like:

@variables {
    myColor: #123456;
}

The variable itself need to be defined by a named ICSSVariables adapter on request. We can register it by an own zcml directive:

<browser:cssvarDefinition
  name="foodef"
  file="foodef.css"
/>

Now we just need to tell our first css file which definition to use. Here theres no common syntax, so we put it in an comment:

/# vardef(foodef) /#
div.foo {
    color: var(myColor);
}

If we now in browser look at http://mydomain.tld/++resource++foo it results in:

/# vardef(foodef) /#
div.foo {
    color: #123456;
}

For resource directories as defined by zope.app.publisher the special CSS handling is registered for every CSS file if this module is imported.

This package is tested with Zope 3.5dev KGS (Python 2.6 )and in Zope 2.10.7 (with Plone 3.3 and Python 2.4).