Added gravity

[wxWidgets.git] / wxPython / docs / wxPackage.txt

=========================
 The wxPython wx Package
=========================

--------------------------------------------------
 Or, how to survive the new wx namespace changes.
--------------------------------------------------

:Author: Patrick K. O'Brien
:Author: Robin Dunn
:Contact: pobrien@orbtech.com
:Organization: Orbtech_
:Date: $Date$
:Revision: $Revision$

.. _Orbtech: http://www.orbtech.com/

.. contents::


Introduction
============

In the begining there was Python, and Python had modules, and Python
was good.  But after a time Guido looked on Python and saw that Python
needed organizational assistance, and so Guido took code from Python's
side and created Packages and then Python was very good.  About this
time wxPython was reborn, and wxPython used Packages, but being young
and trying to use a new technology wxPython did not know how to use
Packages effectivly.  wxPython was good, but dreamed of being much
better...

Now many years later, after tons of code reorganization and build
hacking wxPython has reached that goal.  In version 2.4.1 a prototype
of this new structure was introduced that dynamically built at import
time a new toplevel package named simply "wx" that contained all the
items from wxPython.wx but with the names edited to remove the wx
prefix.  Now in 2.5 the final phase of that switcheroo has been
completed and the *real* classes, functions and constants are now
located in the wx package, leaving some compatibility modules in
wxPython.wx.  This document should answer all the questions you might
have concerning the new wx package.  Please also take a look at the
`2.5 Migration Guide`_ to see notes about other big differences in
this release.

.. _2.5 Migration Guide: MigrationGuide.html

Why change anything?
====================

This change is being made for a couple of reasons.  The first reason
is to discourage the use of ``import *``, which is a dangerous
technique that can create name conflicts and bloated namespaces.

The second reason is to remove what some perceive to be a "wart."  For
example, the following code is rather ugly in that the "wx" prefix on
the wxFrame class name is no longer useful when you're using the wx
module prefix::

    from wxPython import wx

    class Frame(wx.wxFrame)

The new wx package allows you to write code like this, instead::

    import wx

    class Frame(wx.Frame)

The third reason is that the wxWindows project has considered doing
the same thing (implement a new wx namespace and drop the "wx" prefix)
and we want wxPython to lead the way.


What does the new wx package do?
================================

As mentioned in the Introduction, wxPython 2.4.1 introduced a way of
getting to this new syntax as quickly as possible.  It would import
the old names (like "wxFrame") from the old package and then create new
names in the wx package  without the wx prefix, (like "Frame".)
Starting with wxPython 2.5 the renaming is moved up to the wxPython
build step, so the real classes and etc. are actually named with the
new name (like "Frame") and are located in the new wx package.

For compatibility the old wxPython package still exists, but now it is
populated with modules that simply import the new names and then
"reverse-renames" them to the old names.  It probably sounds a bit
complicated, but it is mostly automated and so it  doesn't cause
problems in most cases.


Will any of this effect my existing code?
=========================================

No.  Your existing code will continue to work and be supported for
some time.  It will be up to you to decide when to switch to the new
syntax.  But all new documentation and code examples will use the new
syntax.  So don't wait too long.  You wouldn't want anyone calling you
old-fashioned, would you?

When you import from wxPython.wx and use a class with the old name,
such as wxButton, you are actually using the wx.Button class.  I
expect that the vast majority of the existing code should work fine
using this scheme.  The only things that may cause problems is if your
old code is depending on some of the implemtation details, or if you
are using other things that have changed in the API.  See the
`Migration Guide`_ for more details.

.. _Migration Guide: MigrationGuide.html


What about all the other modules, like grid, html, and stc?
===========================================================

There's more to the old wxPython than just the wxPython.wx module.
And we've got those extra modules covered as well.  Each of those
modules (as well as the lib subpackage) has been moved to the new wx
package and reverse-renamers have been placed in the wxPython package
as needed.


How do I use this new wx package?
=================================

The wx package is automatically created when you install wxPython
version 2.4.1 or higher.  So all you have to do is::

    import wx


What are the issues with converting old code to use the new wx package?
======================================================================= 

Obviously, you need to change your import statements from::

    from wxPython import wx

or::

    from wxPython.wx import *

to::

    import wx

Then you need to refer to wx attributes without a "wx" prefix, such
as::

    class MyFrame(wx.Frame):

In most cases, existing code can be modified with a simple search and
replace.



Where can I find example programs using the new wx syntax?
==========================================================

The wxPython demo application and most of the sample apps have been
converted to use the new ``import wx`` style of programming with
wxPython, so there are lots of examples to look at and to play with.
Here is one of them, it is the ``simple`` sample.


.. include:: ../samples/simple/simple.py
   :literal: