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A compatibility library for PyQt4, PyQt5 and PySide

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A compatibility library for PyQt4, PyQt5 and PySide.

Warning: This is a pre-alpha version that should not be used in production. Backward compatibility is not guaranteed at this point.


This package requires Python 2.7 or 3.2-3.5 with six and one of the following backends: PyQt4, PySide, PyQt5.

It can be installed with,

pip install git+

Quick start

Assuming you have a GUI script written with PyQt4 (or any other backend), you can attempt to run it with PySide (or any other backend) using,

SIQT_BACKEND_FORCE='PySide' python -m SiQt

Note that the compatibility hooks are still being actively developped and this may fail due to API differences


SiQt provides a layer of abstraction to work with the existing Python Qt libraries.

1. Aliasing

The SiQt package will redirect imports to the active PyQt/PySide backend:

import SiQt

from SiQt import QtCore, Qt # or any other module that would be imported from PyQt4

2. Import interception

With the force=True option, imports of PyQt4, PyQt5, PySide can be intercepted to load SiQt instead, which itself redirects to the active PyQt/PySide backend:

import SiQt
SiQt.use('PyQt5', force=True)

import PyQt4
import PyQt4.QtCore

print(PyQt4.__name__)              # SiQt
print(SiQt.backend)                # PyQt5
print(PyQt4.QtCore.QT_VERSION_STR) # 5.5.1

3. Compatibility layer

By default, SiQt.use is called with the mode='compatible' argument, which attempts to compensate the differences in the API between backends (in developpement). Alternatively, one can set mode='strict' to avoid this behaviour.

Command line use

Most of the SiQt functionality is accessible through command line, where the SiQt.use arguments can be passed as environment variables:

  • SIQT_BACKEND='name' is equivalent to SiQt.use('name', force=False)
  • SIQT_BACKEND_FORCE='name' is equivalent to SiQt.use('name', force=True)
  • SIQT_MODE='name' is equivalent to SiQt.use(..., mode='mode')

SiQt can be enabled on any script without changing its source code with,

SIQT_BACKEND_FORCE='name' python -m SiQt

Unit tests

The test suite can be run with,

python -c "from SiQt.siqt import tests;"

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Files for SiQt, version 0.2.0a1
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