App FeaturePython

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Introduction

An Feature.svg App FeaturePython object, or formally an App::FeaturePython, is a simple instance of the App DocumentObject in Python.

This is a simple object that by default doesn't have many properties, for example, no placement nor topological shape. This object is for general purpose use; depending on the properties that are assigned to it, it can be used to manage different types of data.

FreeCAD core objects.svg

Simplified diagram of the relationships between the core objects in the program. The App::FeaturePython class is a simple implementation of the App::DocumentObject that can be used for any purpose, as it doesn't have a TopoShape by default.


Usage

The App FeaturePython is an internal object, so it cannot be created from the graphical interface. It is meant to be sub-classed by classes that will handle different types of data.

See Scripting for more information.

Properties

An App FeaturePython (App::FeaturePython class) is derived from the basic App DocumentObject (App::DocumentObject class), therefore it shares all the latter's properties.

In addition to the properties described in App DocumentObject, the FeaturePython has a basic view provider, so it does appear in the tree view.

See Property for all property types that scripted objects can have.

These are the properties available in the property editor. Hidden properties can be shown by using the Show all command in the context menu of the property editor.

Data

Base

  • DataLabel (String): the user editable name of this object, it is an arbitrary UTF8 string.

Hidden properties Data

  • DataExpression Engine (ExpressionEngine): a list of expressions. By default, it is empty [].
  • DataLabel2 (String): a longer, user editable description of this object, it is an arbitrary UTF8 string that may include newlines. By default, it is an empty string "".
  • DataProxy (PythonObject): a custom class associated with this object.
  • DataVisibility (Bool): whether to display the object or not.

View

Base

  • ViewDisplay Mode (Enumeration): it is empty by default.
  • ViewOn Top When Selected (Enumeration): Disabled (default), Enabled, Object, Element.
  • ViewSelection Style (Enumeration): Shape (default), BoundBox. If the option is Shape, the entire shape (vertices, edges, and faces) will be highlighted in the 3D view; if it is BoundBox only the bounding box will be highlighted.
  • ViewShow In Tree (Bool): if it is True, the object appears in the tree view. Otherwise, it is set as invisible.
  • ViewVisibility (Bool): if it is True, the object appears in the 3D view; otherwise it is invisible. By default this property can be toggled on and off by pressing the Space bar in the keyboard.

Hidden properties View

  • ViewProxy (PythonObject): a custom view provider class associated with this object.

Scripting

See also: FreeCAD Scripting Basics, and scripted objects.

See Part Feature for the general information on adding objects to the program.

An App FeaturePython is created with the addObject() method of the document.

import FreeCAD as App

doc = App.newDocument()
obj = App.ActiveDocument.addObject("App::FeaturePython", "Name")
obj.Label = "Custom label"

For example, the Draft Text, Draft Dimension, and Working plane proxy elements of the Draft Workbench are App::FeaturePython objects with a custom icon and additional properties. They hold data but not an actual Part TopoShape.

If the desired object should have a placement, a shape, an attachment, or other complex properties, it is better to create one of the more complex classes, for example, App GeoFeature, Part Feature, or Part Part2DObject.