================
Upgrading Genshi
================


.. contents:: Contents
   :depth: 2
.. sectnum::


------------------------------------
Upgrading from Genshi 0.5.x to 0.6.x
------------------------------------

Required Python Version
-----------------------

Support for Python 2.3 has been dropped in this release. Python 2.4 is
now the minimum version of Python required to run Genshi.

The XPath engine has been completely overhauled for this version. Some
patterns that previously matched incorrectly will no longer match, and
the other way around. In such cases, the XPath expressions need to be
fixed in your application and templates.


------------------------------------
Upgrading from Genshi 0.4.x to 0.5.x
------------------------------------

Error Handling
--------------

The default error handling mode has been changed to "strict". This
means that accessing variables not defined in the template data will
now generate an immediate exception, as will accessing object
attributes or dictionary keys that don't exist. If your templates rely
on the old lenient behavior, you can configure Genshi to use that
instead. See the documentation for details on how to do that. But be
warned that lenient error handling may be removed completely in a
future release.

Match Template Processing
-------------------------

There has also been a subtle change to how ``py:match`` templates are
processed: in previous versions, all match templates would be applied
to the content generated by the matching template, and only the
matching template itself was applied recursively to the original
content. This behavior resulted in problems with many kinds of
recursive matching, and hence was changed for 0.5: now, all match
templates declared before the matching template are applied to the
original content, and match templates declared after the matching
template are applied to the generated content. This change should not
have any effect on most applications, but you may want to check your
use of match templates to make sure.

Text Templates
--------------

Genshi 0.5 introduces a new, alternative syntax for text templates,
which is more flexible and powerful compared to the old syntax. For
backwards compatibility, this new syntax is not used by default,
though it will be in a future version. It is recommended that you
migrate to using this new syntax. To do so, simply rename any
references in your code to ``TextTemplate`` to ``NewTextTemplate``. To
explicitly use the old syntax, use ``OldTextTemplate`` instead, so
that you can be sure you'll be using the same language when the
default in Genshi is changed (at least until the old implementation is
completely removed).

``Markup`` Constructor
----------------------

The ``Markup`` class no longer has a specialized constructor. The old
(undocumented) constructor provided a shorthand for doing positional
substitutions. If you have code like this:

.. code-block:: python

  Markup('<b>%s</b>', name)

You must replace it by the more explicit:

.. code-block:: python

  Markup('<b>%s</b>') % name

``Template`` Constructor
------------------------

The constructor of the ``Template`` class and its subclasses has changed
slightly: instead of the optional ``basedir`` parameter, it now expects
an (also optional) ``filepath`` parameter, which specifies the absolute
path to the template. You probably aren't using those constructors
directly, anyway, but using the ``TemplateLoader`` API instead.


------------------------------------
Upgrading from Genshi 0.3.x to 0.4.x
------------------------------------

The modules ``genshi.filters`` and ``genshi.template`` have been
refactored into packages containing multiple modules. While code using
the regular APIs should continue to work without problems, you should
make sure to remove any leftover traces of the files ``filters.py``
and ``template.py`` in the ``genshi`` package on the installation
path (including the corresponding ``.pyc`` files). This is not
necessary when Genshi was installed as a Python egg.

Results of evaluating template expressions are no longer implicitly
called if they are callable. If you have been using that feature, you
will need to add the parenthesis to actually call the function.

Instances of ``genshi.core.Attrs`` are now immutable. Filters
manipulating the attributes in a stream may need to be updated. Also,
the ``Attrs`` class no longer automatically wraps all attribute names
in ``QName`` objects, so users of the ``Attrs`` class need to do this
themselves. See the documentation of the ``Attrs`` class for more
information.


---------------------
Upgrading from Markup
---------------------

Prior to version 0.3, the name of the Genshi project was "Markup". The
name change means that you will have to adjust your import statements
and the namespace URI of XML templates, among other things:

* The package name was changed from "markup" to "genshi". Please
  adjust any import statements referring to the old package name.
* The namespace URI for directives in Genshi XML templates has changed
  from ``http://markup.edgewall.org/`` to
  ``http://genshi.edgewall.org/``. Please update the ``xmlns:py``
  declaration in your template files accordingly.

Furthermore, due to the inclusion of a text-based template language,
the class::

  markup.template.Template

has been renamed to::

  genshi.template.MarkupTemplate

If you've been using the Template class directly, you'll need to
update your code (a simple find/replace should do—the API itself
did not change).