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Defining 'all-purpose' macros
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To define an 'all-purpose' macro, i.e. a macro, that can render
objects of (nearly) any type and thus be accessed from any
other page template, just set a very general context for your macro
view:

.. code-block:: python
   :linenos:

    from zope.interface import Interface
    import grok

    class Master(grok.View):
        grok.context(Interface)

and reference the macros of the associated pagetemplate like this::

    context/@@master/macros/<macro-name>

Because the macros in ``Master`` now are 'bound' (in fact their view
is bound) to ``Interface`` and every Grok application, model or
container implements some interface, the ``Master`` macros will be
accessible from nearly every other context. ``Master`` promises to be
a view for every object, which implements ``Interface``.