zope.configuration.zopeconfigure¶
Zope configure directive
This file contains the implementation of the Zope configure directive. It is broken out in a separate file to provide an example of a grouping directive.
The zope configuration directive is a pure grouping directive. It doesn’t compute any actions on it’s own. Instead, it allows a package to be specified, affecting the interpretation of relative dotted names and file paths. It also allows an i18n domain to be specified. The information collected is used by subdirectives.
To define a grouping directive, we need to do three things:
Define a schema for the parameters passed to the directive
Define a handler class.
Register the class
The parameter schema is given by IZopeConfigure. It specifies a
package parameter and an i18n_domain parameter. The package parameter
is specified as a GlobalObject
. This means it must be given as a
dotted name that can be resolved through import. The i18n domain is
just a plain (not unicode) string.
The handler class has a constructor that takes a context to be adapted
and zero or more arguments (depending on the paramter schema). The
handler class must implement
zope.configuration.interfaces.IGroupingContext
, which defines
hooks before
and after
, that are called with no arguments
before and after nested directives are processed. If a grouping
directive handler creates any actions, or does any computation, this
is normally done in either the before
or after
hooks.
Grouping handlers are normally decorators.
The base class,
zope.configuration.config.GroupingContextDecorator
, is normally
used to define grouping directive handlers. It provides:
An implementation of
IConfigurationContext
, which grouping directive handlers should normally implement,A default implementation of
IGroupingContext
that provides empty hooks.Decorator support that uses a
__getattr__
method to delegate attribute accesses to adapted contexts, andA constructor that sets the
context
attribute to the adapted context and assigns keyword arguments to attributes.
The class ZopeConfigure
provides handling for the configure
directive. It subclasses GroupingContextDecorator
, and overrides the
constructor to set the basepath
attribute if a package
argument
is provided. Note that it delegates the job of assigning paramters to
attribute to the GroupingContextDecorator
constructor.
The last step is to register the directive using the meta
configuration directive. If we wanted to register the Zope
configure
directive for the zope
namespace, we’d use a
meta-configuration directive like:
<meta:groupingDirective
namespace="http://namespaces.zope.org/zope"
name="configure"
schema="zope.configuration.zopeconfigure.IZopeConfigure"
handler="zope.configuration.zopeconfigure.ZopeConfigure"
>
Zope configure
The ``configure`` node is normally used as the root node for a
configuration file. It can also be used to specify a package or
internationalization domain for a group of directives within a
file by grouping those directives.
</meta:groupingDirective>
We use the groupingDirective
meta-directive to register a grouping
directive. The parameters are self explanatory. The textual contents
of the directive provide documentation text, excluding parameter
documentation, which is provided by the schema.
(The Zope configuration
directive is actually registered using a
lower-level Python API because it is registered for all namespaces,
which isn’t supported using the meta-configuration directives.)