========================== Referencing a simple macro ========================== How to reference a simple macro? -------------------------------- In ``index.pt`` we now want to *use* the macro defined in ``mymacros.pt``. Using a macro means to let it render a part of another page template, especially, filling the slots defined in ``mymacros.pt`` with content defined in ``index.pt``. You call macros with the ``METAL`` attribute:: metal:use-macro="" Our ``app_templates/index.pt`` can be that simple: .. code-block:: html Watching:: http://localhost:8080/test/index should now give the same result as above, although we didn't call ``mymacros`` in browser, but ``index``. That's what macros are made for. When we fill the slots, we get different content rendered within the same macro. You can fill slots using:: metal:fill-slot="" where the slot-name must be defined in the macro. Now, change ``index.pt`` to: .. code-block:: html

My content from index.pt

and you will get the output:: The content: My content from index.pt The pattern of the macro reference (the ) used here is:: context//macros/ whereas ``context`` references the object being viewed, which in our case is the ``Sample`` application. In plain English we want Zope to look for a view for a ``Sample`` application object (``test``) which is called ``mymacros`` and contains a macro called ``mypage``. The logic behind this is, that views are always registered for certain object types. Registering a view with some kind of object (using ``grok.context()`` for example), means, that we promise, that this view can render objects of that type. (It is up to you to make sure, that the view can handle rendering of that object type). It is not a bad idea to register views for interfaces (instead of implementing classes), because it means, that a view will remain usable, while an implementation of an interface can change. [FIXME: Is this a lie?] This is done in the section Defining 'all-purpose' macros.