Table Of Contents
Properties¶
Kivy introduces a new way of declaring properties within a class. Before:
class MyClass(object):
def __init__(self):
super(MyClass, self).__init__()
self.numeric_var = 1
After, using Kivy’s properties:
class MyClass(EventDispatcher):
numeric_var = NumericProperty(1)
These properties implement the Observer pattern. They help you to:
- Easily manipulate widgets defined in the Kv language
- Automatically observe any changes and dispatch functions/code accordingly
- Check and validate values
- Optimize memory management
To use them, you have to declare them at class level. That is, directly in
the class, not in any method of the class. A property is a class attribute
that will automatically create instance attributes. Each property by default
provides an on_<propertyname> event that is called whenever the property’s
state/value changes.
- Kivy provides the following properties:
NumericProperty,StringProperty,ListProperty,ObjectProperty,BooleanProperty,BoundedNumericProperty,OptionProperty,ReferenceListProperty,AliasProperty,DictProperty,
For an in-depth explanation, take a look at Properties.