The below methods account for ~99% of the use-cases power-users may have for Python proxy classes.
||Called during document recomputes||Do not call |
||Called before a property value is changed|
||Called after a property is changed|
||Called after a document is restored or a FeaturePython object is copied.||Occasionally, references to the FeaturePython object from the class, or the class from the FeaturePython object may be broken, as the class |
It is not uncommon to encounter a situation where the Python callbacks are not being triggered as they should. Beginners in this area can rest assured that the FeaturePython callback system is not fragile or broken. Invariably when callbacks fail to run it is because a reference is lost or undefined in the underlying code. If, however, callbacks appear to be breaking with no explanation, providing object/proxy references in the
onDocumentRestored() callback (as noted in the first table above) may alleviate these problems. Until you are comfortable with the callback system, it may be useful to add print statements in each callback to print messages to the console during development.
The below methods are for advanced usage of Python proxy classes and you won't have a need for them most of the time.
Determining available Python methods
Within the FeaturePython Template Class exists various
imp-><method name>() calls.
Each of these correspond to an available bound Python method.
imp->execute() on line 193 means the
execute method is available.
init() are special-cases and don't follow the above heuristic.
- FreeCAD GitHub: FeaturePython.h - public API
- FreeCAD GitHub: FeaturePythonT template class
- FreeCAD Forum Discussion: Scripted Objects Complete Method Reference