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Porting Orange2 widgets to Orange3

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Aleš Erjavec edited this page Oct 30, 2015 · 11 revisions

Changes:

  • The widget meta data descriptions (name, desciption, icon, ...) are moved into the OWWidget's class namespace. E.g. in Orange2 the widget meta definitions would look like

    """
<name>Widget</name>
<description>An awesome widget</description>
...
"""

    or

    NAME = "Widget"
DESCRIPTION = "An awesome widget"
ICON =

    defined at the module level namespace

    In Orange 3 this is changed to

    class OWAwesome(OWWidget):
    #: Widget's descriptive name
    name = "Widget"
    #: A short widget description
    description = "An awesome widget"
    #: An icon resource file path for this widget
    #: (a path relative to the module where this widget is defined)
    icon = "icons/someicon.svg"
    #: Priority within a category
    priority = 0

    #: A list of input definitions (here an input named "Bar" taking a
    #: value of type `object`, and specifying that a method "set_foo" is
    #: the one to receive the input)
    inputs = [("Foo", object, "set_foo")]

    #: A list of output definitions (here on output named "Bar"
    #: of type object)
    outputs = [("Bar", object)]

    ...

    def set_foo(self, foo):
        """Set the foo widget input"""
        ...

  • The OWWidget.__init__ method no longer takes any parameters. The signalManager and title are no longer passed to the __init__, while the parameters specifying the requested GUI layout, ... are (again) defined in the widget's class namespace. E.g. what was once in Orange2

    class FooWidget(OWWidget):
    def __init__(self, parent=None, signalManager=None, title="blabla"):
        OWWidget.__init__(self, parent, signalManager, title, wantMainArea=False, ...)

    is now changed to

    class FooWidget(OWWidget):
    #: Do not want the default layout with the main area.
    want_main_area = False
    def __init__(self):
        super().__init__()

  • How settings are defined has changed. In Orange2 the settings (widget members) were specified by a class variable settingsList containing a list of member names to store.

    class FooWidget(OWWidget):
    settingsList = ["bar"]
    def __init__(self, *args, *kwargs)
         OWWidget.__init__(self, *args, **kwargs)
         # initialize the 'members' to the defaults
         self.bar = 2
         # load/restore the saved state; bar member would be modified here
         self.loadSettings()

    In Orange3 the same is accomplished by defining/initializing the settings in the class namespace using the Orange.widget.setttings.Setting 'descriptor'

    from Orange.widgets.settings import Setting
class FooWidget(OWWidget):
    #: Initialize bar and mark it as a persistent setting (i.e. it will be restored
    #: from a previous session or a saved workflow)
    bar = Setting(2)
    def __init__(self):
        super().__init__()
        # note that there is no self.loadSettings() or equivalent the `bar` member was
        # already restored and is ready for use.
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