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PySide Frequently Asked Questions

This is a list of Frequently Asked Questions about general PySide topics.


What is PySide?

PySide is Python library to create cross-platform graphical user interfaces by providing access to the underlying Qt framework. PySide and its complete generation toolchain is available under LGPL license. This allows developers to create Qt and Qt Quick applications in Python programming language at no cost.

Why develop new Qt Python bindings?

We researched existing options in the market, but due to our licensing and technical requirements, we decided that building our own bindings was the best option for us.

What about PyQt?

Initial research into Python bindings for Qt involved speaking with Riverbank Computing, the makers of PyQt. We had several discussions with them to see if it was possible to use PyQt to achieve our goals. Unfortunately, a common agreement could not be found , so in the end we decided to proceed with PySide.

Will PySide be open for community involvement?

Absolutely! While we plan on continuing to develop PySide, we are aware that it will be most successful if we can have additional community members joining in on the development and testing. PySide community resources can be found at this website.

Python Library

What’s the latest version of PySide?

PySide 1.2.1 was released on August 16, 2013.

Which platforms is PySide available for?

PySide packages are available for Linux/X11, Maemo 5, Microsoft Windows, and Mac OS X. There is an ongoing effort in the community to port PySide to Symbian and Android.

Which Qt versions are supported?

The following Qt versions are supported: 4.6, 4.7 and 4.8. Version 5.x is currently not supported.

How about the Python versions?

As of 2011-03-28, it is possible to build PySide against Python 2.5, 2.6, 2.7 and 3.x. See the page on Python 3 Support.

Importing PySide produces a DLL error, what can I do?

The following errors are caused when PySide loads the wrong Qt DLL:

Cannot mix incompatible Qt library (version 0×40701) with this library (version 0×40702)

ImportError: DLL load failed: The specified procedure could not be found.

This is usually because of an existing PyQt installation. PyQt prepends its bin directory to the Windows system PATH variable while PySide appends to it. Editing the system PATH variable so that the PySide directory appears before the PyQt and any other Qt directory should resolve the error(s). It is also generally not a good idea to import both PyQt and PySide at the same time. Note that some packages will import PyQt when imported themselves (eg. matplotlib/pylab with Qt set as the default backend etc).