Creating an extension
Overview
Relevant files
Let’s assume that your extension is called my_extension. In that case, your extension corresponds to a folder called my_extension, containing at least the following 2 files:
my_extension/
info.yaml
my_extension.py
Extension information
Extension information is defined in info.yaml. This works the same way as for plug-ins, with the exception that you don’t define any controls. For more information, see:
Writing the extension code
The main extension code is placed in my_extension.py. This file has one class, my_extension, which inherits libqtopensesame.extensions.base_extension.base_extension. So a basic (non-functional) extension class looks like this:
from libqtopensesame.extensions import base_extension
class my_extension(base_extension):
pass
Activating an extension through the menu/ toolbar
An extension can appear in the menu or main toolbar of OpenSesame. This requires that you define several fields in info.yaml:
label: Example extension
icon: go-next
tooltip: Some tooltip
menu:
index: 0
separator_after: false
separator_before: false
submenu: Example
toolbar:
index: -1
separator_after: false
separator_before: true
The label is the text that will appear in the menu. The icon is a freedesktop-compliant icon name that specifies the icon that will appear in the menu and/ or toolbar. The index gives the position of the extension in the menu/ toolbar, and works like a list index. That is, negative values are relative to the last entry, where -1 puts your extension at the end.
To have your extension respond to menu/ toolbar activation, implement the activate() method:
from libopensesame import debug
from libqtopensesame.extensions import base_extension
class my_extension(base_extension):
def activate(self):
debug.msg(u'My extension was activated!')
Listening for events
OpenSesame fires events whenever something important happens. For example, the save_experiment event is fired when an experiment is saved. To have your extension listen to an event, simply implement a method with the name event_[event name].
from libopensesame import debug
from libqtopensesame.extensions import base_extension
class my_extension(base_extension):
def event_save_experiment(self, path):
debug.msg(u'Event fired: save_experiment(path=%s)' % path)
Note that some events take keyword arguments, such as path in the case of save_experiment. The keyword signature of your function must match the expected keyword signature. A list of events can be found in the example extension.
Examples
- The
exampleextension is a dummy extension that demonstrates how to implement a basic extension. - Other examples can be found in the
extensionsfolder included with OpenSesame.
