Launching Pychron


All pychron applications are based on Enthought’s envisage application framework. The envisage framework is used to make pychron extensible and pluggable. For more information see

Entry Point

The entry point for all pychron applications are scripts located in the launchers package. For example, to launch pyexperiment

cd pychron
python launchers/

This script calls imports and calls entry_point from the helpers module.

The entry_point function performs multiples tasks.

  1. sets the GUI backend to Qt ETSConfig.toolkit = "qt4"

  2. updates the pythonpath

  3. sets global variables and pychron filesystem paths

  4. constructs missing directories in Pychrondata…

  5. sets up logging

  6. calls the launch function

The launch function takes one argument, a PychronApplication class. The launch function is located at pychron.envisage.pychron_run.

launch does the following

  1. checks that necessary dependencies are installed

  2. constructs the application object using app_factory

  3. launches the application by calling the application’s run method

During Step. 2 the necessary plugins are constructed and added to the application. The plugins to use are specified in the initialization.xml file. Parsing of the initialization.xml file is handled by an InitializationParser object.


If Hardware plugins are included, such as FusionsCO2, the HardwarePlugin is added to the application plugins. When the HardwarePlugin starts, it uses an Initalizer object to bootstrap the necessary managers and devices.