Library Package¶

Motivation

Organize code related to the geometry parts, and allow parts to be made from a command-line context.

The library package, located within the root level of the repository, contains code for the geometry of parts, and how those parts relate to each other.

The “geometry of parts” is defined as:

Geometric primitives that make up parts such as vertexes, edges, and faces
Basic shapes such as boxes, circles, cones, and cylinders
and operations on, or between these primitives and basic shapes such as extrusion, chamfer, union, difference, or intersection.

For a formal introduction to these concepts, see Solid modeling, Constructive solid geometry, and Boundary representation.

FreeCAD exposes the ability to define and manipulate the geometry of parts through it’s Part module.

See the FreeCAD Wiki on Creating and manipulating geometry, and Topological data scripting for additional details.

Sub-packages¶

The following are typical sub-packages the library package may contain:

<library package>/
├── part/
├── model/
├── attachment/
└── __init__.py

Note

The library package typically only contains sub-packages without any direct modules.

Part Sub-package¶

The part sub-package exposes Part Classes encapsulating the geometry for parts, and is made up of further private sub-packages for each part.

For example, the part package in the ose-3d-printer-workbench contains the following:

<library package>/part/
├── _axis/
├── _extruder/
├── _frame/
├── _heated_bed/
└── __init__.py

The _axis/ package exposes an Axis class for “making” the geometry of an axis.

Similarly, the _extruder/ package exposes an Extruder class, _heated_bed/ exposes a HeatedBed class, and _frame/ exposes multiple classes related to a frame.

All the exposed part classes are imported within the __init__.py file, and declared public using __all__:

"""Parts for a 3D Printer."""
from ._axis import Axis
from ._extruder import Extruder
from ._frame import AngledBarFrame, AngleFrameConnector, CNCCutFrame
from ._heated_bed import HeatedBed

__all__ = [
    'AngleFrameConnector',
    'AngledBarFrame',
    'Axis',
    'CNCCutFrame',
    'Extruder',
    'HeatedBed'
]

Tip

It’s best-practice to include docstring for all public packages.

For more information on part classes themselves, see Part Classes.

Model Sub-package¶

The model sub-package exposes Model Classes for making the static geometry of part classes dynamic.

For example, the model package in the ose-3d-printer-workbench contains the following:

<library package>/model
├── _axis/
├── _extruder/
├── _frame/
├── _heated_bed/
└── __init__.py

The _axis/ package exposes an AxisModel class for “making” the geometry of the Axis part class dynamic.

Similarly, the _extruder/ package exposes an ExtruderModel class, _heated_bed/ exposes a HeatedBedModel class, and _frame/ exposes a FrameModel class.

All the exposed model classes are imported within the __init__.py file, and declared public using __all__:

"""Models for 3D Printer parts."""
from ._axis import AxisModel
from ._extruder import ExtruderModel
from ._frame import FrameModel
from ._heated_bed import HeatedBedModel

__all__ = [
    'AxisModel',
    'ExtruderModel',
    'FrameModel',
    'HeatedBedModel'
]

For more information on model classes themselves, see Model Classes.

Attachment Sub-package¶

The attachment sub-package exposes Attachment Functions that return keyword arguments to make one part appear “attached to” another.

For example, the attachment package in the ose-3d-printer-workbench contains the following:

<library package>/attachment
├── _get_axis_frame_attachment_kwargs/
├── _get_extruder_axis_attachment_kwargs/
├── _get_heated_bed_frame_axis_attachment_kwargs/
└── __init__.py

The _get_axis_frame_attachment_kwargs/ package exposes an _get_axis_frame_attachment_kwargs function for “attaching” the axis to the frame.

Similarly, the _get_extruder_axis_attachment_kwargs/ package exposes a get_extruder_axis_attachment_kwargs function, and _get_heated_bed_frame_axis_attachment_kwargs/ exposes a get_heated_bed_frame_axis_attachment_kwargs function.

All the exposed attachment functions are imported within the __init__.py file, and declared public using __all__:

"""Attachment functions to make 3D Printer parts appear attached to each other."""
from ._get_axis_frame_attachment_kwargs import (
    get_axis_frame_attachment_kwargs, get_default_axis_creation_kwargs)
from ._get_extruder_axis_attachment_kwargs import \
    get_extruder_axis_attachment_kwargs
from ._get_heated_bed_frame_axis_attachment_kwargs import \
    get_heated_bed_frame_axis_attachment_kwargs

__all__ = [
    'get_axis_frame_attachment_kwargs',
    'get_default_axis_creation_kwargs',
    'get_extruder_axis_attachment_kwargs',
    'get_heated_bed_frame_axis_attachment_kwargs'
]

For more information on attachment functions themselves, see Attachment Functions.