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Properties play a very important role in FreeCAD. As objects in FreeCAD are "parametric", this means that their behavior is defined by their properties, and how these properties are used as input for their class methods. |
Properties play a very important role in FreeCAD. As objects in FreeCAD are "parametric", this means that their behavior is defined by their properties, and how these properties are used as input for their class methods. See also [[FeaturePython_Custom_Properties|FeaturePython Custom Properties]] and [[PropertyLink:_InList_and_OutList|PropertyLink: InList and OutList]] |
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== All property types == |
== All property types == |
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Custom [[ |
Custom [[Scripted_objects|scripted objects]] can use any of the property types defined in the base system: |
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{{Code|code= |
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{| class="sortable wikitable" |
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Bool |
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|- |
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Float |
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! Name !! Unit (if any) !! Remark |
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FloatList |
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|- |
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FloatConstraint |
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| Acceleration || style="text-align:center;" | m/s^2 |
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Angle |
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|- |
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Distance |
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| AmountOfSubstance || style="text-align:center;" | mol |
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ExpressionEngine |
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|- |
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Integer |
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| Angle || style="text-align:center;" | ° |
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IntegerConstraint |
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|- |
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Percent |
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| Area || style="text-align:center;" | m^2 |
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Enumeration |
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|- |
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IntegerList |
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| Bool || |
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String |
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|- |
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StringList |
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| BoolList || |
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Length |
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|- |
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Link |
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| Color || |
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LinkList |
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|- |
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LinkSubList |
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| ColorList || |
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Matrix |
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|- |
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Vector |
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| CurrentDensity || style="text-align:center;" | A/m^2 || {{Version|0.21}} |
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VectorList |
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|- |
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VectorDistance |
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| Density || style="text-align:center;" | kg/m^3 |
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Placement |
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|- |
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PlacementLink |
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| Direction || |
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PythonObject |
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|- |
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Color |
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| DissipationRate || style="text-align:center;" | m^2/s^3 || {{Version|0.21}} |
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ColorList |
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|- |
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Material |
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| Distance || style="text-align:center;" | m |
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Path |
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|- |
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File |
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| DynamicViscosity || style="text-align:center;" | Pa*s || {{Version|0.21}} |
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FileIncluded |
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|- |
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PartShape |
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| ElectricalCapacitance || style="text-align:center;" | F || {{Version|0.21}} |
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FilletContour |
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|- |
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Circle |
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| ElectricalConductance || style="text-align:center;" | S || {{Version|0.21}} |
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}} |
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| ElectricalConductivity || style="text-align:center;" | S/m || {{Version|0.21}} |
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| ElectricalInductance|| style="text-align:center;" | H || {{Version|0.21}} |
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| ElectricalResistance || style="text-align:center;" | Ohm || {{Version|0.21}} |
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| ElectricCharge || style="text-align:center;" | C || {{Version|0.21}} |
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| ElectricCurrent || style="text-align:center;" | A || {{Version|0.21}} |
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| ElectricPotential || style="text-align:center;" | V || {{Version|0.20}} |
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| Enumeration || |
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| ExpressionEngine || |
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| File || |
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| FileIncluded || |
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| Float || |
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| FloatConstraint || |
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| FloatList || |
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| Font || |
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|- |
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| Force || style="text-align:center;" | N |
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| Frequency || style="text-align:center;" | Hz |
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|- |
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| HeatFlux || style="text-align:center;" | W/m^2|| {{Version|0.21}} |
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|- |
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| Integer || |
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| IntegerConstraint || |
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| IntegerList || |
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| IntegerSet || |
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| InverseArea || style="text-align:center;" | 1/m^2 || {{Version|0.21}} |
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| InverseLength || style="text-align:center;" | 1/m || {{Version|0.21}} |
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|- |
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| InverseVolume || style="text-align:center;" | 1/m^3 || {{Version|0.21}} |
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| KinematicViscosity || style="text-align:center;" | m^2/s || {{Version|0.21}} |
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| Length || style="text-align:center;" | m |
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|- |
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| Link || |
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|- |
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| LinkChild || |
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| LinkGlobal || |
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| LinkHidden || |
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| LinkList || |
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| LinkListChild || |
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| LinkListGlobal || |
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| LinkListHidden || |
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| LinkSub || |
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| LinkSubChild || |
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| LinkSubGlobal || |
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| LinkSubHidden || |
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| LinkSubList || |
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| LinkSubListChild || |
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| LinkSubListGlobal || |
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| LinkSubListHidden || |
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| LuminousIntensity || style="text-align:center;" | cd || {{Version|0.21}} |
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|- |
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| MagneticFieldStrength || style="text-align:center;" | A/m || {{Version|0.21}} |
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| MagneticFlux || style="text-align:center;" | Wb or V*s || {{Version|0.21}} |
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| MagneticFluxDensity || style="text-align:center;" | T || {{Version|0.21}} |
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| Magnetization || style="text-align:center;" | A/m || {{Version|0.21}} |
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| Map || |
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| Mass || style="text-align:center;" | kg || {{Version|0.21}} |
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| Material || |
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| MaterialList || |
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| Matrix || |
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| PartShape || || a Part property, is accessed as</br>{{incode|Part::PropertyPartShape}} |
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| Path || |
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| Percent || |
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| PersistentObject || |
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| Placement || |
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| PlacementLink || |
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| PlacementList || |
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| Position || |
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| Power || style="text-align:center;" | W || {{Version|0.21}} |
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| Precision || |
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| Pressure || style="text-align:center;" | Pa |
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| PythonObject || |
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| Quantity || |
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| QuantityConstraint || |
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| Rotation || |
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| ShearModulus || style="text-align:center;" | Pa || {{Version|0.21}} |
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| SpecificEnergy || style="text-align:center;" | m^2/s^2 or J/kg || {{Version|0.21}} |
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| SpecificHeat || style="text-align:center;" | J/kg/K || {{Version|0.21}} |
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|- |
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| Speed || style="text-align:center;" | m/s |
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|- |
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| Stiffness || style="text-align:center;" | m/s^2 |
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|- |
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| Stress || style="text-align:center;" | Pa || {{Version|0.21}} |
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| String || |
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| StringList || |
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| Temperature || style="text-align:center;" | K || {{Version|0.21}} |
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| ThermalConductivity || style="text-align:center;" | W/m/K || {{Version|0.21}} |
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|- |
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| ThermalExpansionCoefficient || style="text-align:center;" | 1/K || {{Version|0.21}} |
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|- |
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| ThermalTransferCoefficient || style="text-align:center;" | W/m^2/K || {{Version|0.21}} |
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| Time || style="text-align:center;" | s || {{Version|0.21}} |
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| UltimateTensileStrength || style="text-align:center;" | Pa || {{Version|0.21}} |
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| UUID || |
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| VacuumPermittivity || style="text-align:center;" | s^4*A^2 / (m^3*kg) |
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| Vector || |
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| VectorDistance || |
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| VectorList || |
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| Velocity || style="text-align:center;" | m/s || {{Version|0.21}} |
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| Volume || style="text-align:center;" | l or m^3 |
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| VolumeFlowRate || style="text-align:center;" | l/s or m^3/s || {{Version|0.21}} |
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|- |
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| VolumetricThermalExpansionCoefficient || style="text-align:center;" | 1/K || {{Version|0.21}} |
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| Work || style="text-align:center;" | J || {{Version|0.21}} |
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| XLink || |
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| XLinkList || |
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| XLinkSub || |
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| XLinkSubList || |
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| YieldStrength || style="text-align:center;" | Pa || {{Version|0.21}} |
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|- |
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| YoungsModulus || style="text-align:center;" | Pa || {{Version|0.21}} |
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|} |
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Internally, the property name is prefixed with {{incode|App::Property}}: |
Internally, the property name is prefixed with {{incode|App::Property}}: |
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== Scripting == |
== Scripting == |
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{{Emphasis|See also:}} [[ |
{{Emphasis|See also:}} [[FreeCAD_Scripting_Basics|FreeCAD scripting basics]] |
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A [[ |
A [[Scripted_objects|scripted object]] is created first, and then properties are assigned. |
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{{Code|code= |
{{Code|code= |
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obj = App.ActiveDocument.addObject("Part::Feature", "CustomObject") |
obj = App.ActiveDocument.addObject("Part::Feature", "CustomObject") |
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Nevertheless, {{Emphasis|View}} properties can also be assigned using the view provider object's {{incode|addProperty()}} method. |
Nevertheless, {{Emphasis|View}} properties can also be assigned using the view provider object's {{incode|addProperty()}} method. |
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{{Code|code= |
{{Code|code= |
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obj.ViewObject.addProperty("App::PropertyBool", "SuperVisibility", "Base", "Make the object glow") |
obj.ViewObject.addProperty("App::PropertyBool", "SuperVisibility", "Base", "Make the object glow") |
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They are imported and initialized in {{incode|[https://github.com/FreeCAD/FreeCAD/blob/9c27f1078e5ec516fe882aac1a27f5c6c6174554/src/App/Application.cpp#L1681-L1758 src/App/Application.cpp]}}. |
They are imported and initialized in {{incode|[https://github.com/FreeCAD/FreeCAD/blob/9c27f1078e5ec516fe882aac1a27f5c6c6174554/src/App/Application.cpp#L1681-L1758 src/App/Application.cpp]}}. |
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{{Code|lang=cpp|code= |
{{Code|lang=cpp|code= |
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#include "Property.h" |
#include "Property.h" |
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#include "PropertyExpressionEngine.h" |
#include "PropertyExpressionEngine.h" |
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}} |
}} |
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{{Powerdocnavi{{#translation:}}}} |
{{Powerdocnavi{{#translation:}}}} |
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[[Category:Developer Documentation{{#translation:}}]] |
[[Category:Developer Documentation{{#translation:}}]] |
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[[Category:Python Code{{#translation:}}]] |
[[Category:Python Code{{#translation:}}]] |
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{{clear}} |
Latest revision as of 16:27, 20 May 2023
Introduction
A property is a piece of information like a number or a text string that is attached to a FreeCAD document or an object in a document. Properties can be viewed and - if allowed - modified with the Property editor.
Properties play a very important part in FreeCAD, since it is from the beginning made to work with parametric objects, which are objects defined only by their properties.
Custom scripted objects in FreeCAD can have properties of the following types:
Boolean Float FloatList FloatConstraint Angle Distance Integer IntegerConstraint Percent Enumeration IntegerList String StringList Link LinkList Matrix Vector VectorList Placement PlacementLink Color ColorList Material Path File FileIncluded PartShape FilletContour Circle
Properties play a very important role in FreeCAD. As objects in FreeCAD are "parametric", this means that their behavior is defined by their properties, and how these properties are used as input for their class methods. See also FeaturePython Custom Properties and PropertyLink: InList and OutList
All property types
Custom scripted objects can use any of the property types defined in the base system:
Name | Unit (if any) | Remark |
---|---|---|
Acceleration | m/s^2 | |
AmountOfSubstance | mol | |
Angle | ° | |
Area | m^2 | |
Bool | ||
BoolList | ||
Color | ||
ColorList | ||
CurrentDensity | A/m^2 | introduced in version 0.21 |
Density | kg/m^3 | |
Direction | ||
DissipationRate | m^2/s^3 | introduced in version 0.21 |
Distance | m | |
DynamicViscosity | Pa*s | introduced in version 0.21 |
ElectricalCapacitance | F | introduced in version 0.21 |
ElectricalConductance | S | introduced in version 0.21 |
ElectricalConductivity | S/m | introduced in version 0.21 |
ElectricalInductance | H | introduced in version 0.21 |
ElectricalResistance | Ohm | introduced in version 0.21 |
ElectricCharge | C | introduced in version 0.21 |
ElectricCurrent | A | introduced in version 0.21 |
ElectricPotential | V | introduced in version 0.20 |
Enumeration | ||
ExpressionEngine | ||
File | ||
FileIncluded | ||
Float | ||
FloatConstraint | ||
FloatList | ||
Font | ||
Force | N | |
Frequency | Hz | |
HeatFlux | W/m^2 | introduced in version 0.21 |
Integer | ||
IntegerConstraint | ||
IntegerList | ||
IntegerSet | ||
InverseArea | 1/m^2 | introduced in version 0.21 |
InverseLength | 1/m | introduced in version 0.21 |
InverseVolume | 1/m^3 | introduced in version 0.21 |
KinematicViscosity | m^2/s | introduced in version 0.21 |
Length | m | |
Link | ||
LinkChild | ||
LinkGlobal | ||
LinkHidden | ||
LinkList | ||
LinkListChild | ||
LinkListGlobal | ||
LinkListHidden | ||
LinkSub | ||
LinkSubChild | ||
LinkSubGlobal | ||
LinkSubHidden | ||
LinkSubList | ||
LinkSubListChild | ||
LinkSubListGlobal | ||
LinkSubListHidden | ||
LuminousIntensity | cd | introduced in version 0.21 |
MagneticFieldStrength | A/m | introduced in version 0.21 |
MagneticFlux | Wb or V*s | introduced in version 0.21 |
MagneticFluxDensity | T | introduced in version 0.21 |
Magnetization | A/m | introduced in version 0.21 |
Map | ||
Mass | kg | introduced in version 0.21 |
Material | ||
MaterialList | ||
Matrix | ||
PartShape | a Part property, is accessed asPart::PropertyPartShape
| |
Path | ||
Percent | ||
PersistentObject | ||
Placement | ||
PlacementLink | ||
PlacementList | ||
Position | ||
Power | W | introduced in version 0.21 |
Precision | ||
Pressure | Pa | |
PythonObject | ||
Quantity | ||
QuantityConstraint | ||
Rotation | ||
ShearModulus | Pa | introduced in version 0.21 |
SpecificEnergy | m^2/s^2 or J/kg | introduced in version 0.21 |
SpecificHeat | J/kg/K | introduced in version 0.21 |
Speed | m/s | |
Stiffness | m/s^2 | |
Stress | Pa | introduced in version 0.21 |
String | ||
StringList | ||
Temperature | K | introduced in version 0.21 |
ThermalConductivity | W/m/K | introduced in version 0.21 |
ThermalExpansionCoefficient | 1/K | introduced in version 0.21 |
ThermalTransferCoefficient | W/m^2/K | introduced in version 0.21 |
Time | s | introduced in version 0.21 |
UltimateTensileStrength | Pa | introduced in version 0.21 |
UUID | ||
VacuumPermittivity | s^4*A^2 / (m^3*kg) | |
Vector | ||
VectorDistance | ||
VectorList | ||
Velocity | m/s | introduced in version 0.21 |
Volume | l or m^3 | |
VolumeFlowRate | l/s or m^3/s | introduced in version 0.21 |
VolumetricThermalExpansionCoefficient | 1/K | introduced in version 0.21 |
Work | J | introduced in version 0.21 |
XLink | ||
XLinkList | ||
XLinkSub | ||
XLinkSubList | ||
YieldStrength | Pa | introduced in version 0.21 |
YoungsModulus | Pa | introduced in version 0.21 |
Internally, the property name is prefixed with App::Property
:
App::PropertyBool
App::PropertyFloat
App::PropertyFloatList
...
Remember that these are property types. A single object may have many properties of the same type, but with different names.
For example:
obj.addProperty("App::PropertyFloat", "Length")
obj.addProperty("App::PropertyFloat", "Width")
obj.addProperty("App::PropertyFloat", "Height")
This indicates an object with three properties of type "Float", named "Length", "Width", and "Height", respectively.
Scripting
See also: FreeCAD scripting basics
A scripted object is created first, and then properties are assigned.
obj = App.ActiveDocument.addObject("Part::Feature", "CustomObject")
obj.addProperty("App::PropertyFloat", "Velocity", "Parameter", "Body speed")
obj.addProperty("App::PropertyBool", "VelocityEnabled", "Parameter", "Enable body speed")
In general, Data properties are assigned by using the object's addProperty()
method. On the other hand, View properties are normally provided automatically by the parent object from which the scripted object is derived.
For example:
- Deriving from
App::FeaturePython
provides only 4 View properties: "Display Mode", "On Top When Selected", "Show In Tree", and "Visibility". - Deriving from
Part::Feature
provides 17 View properties: the previous four, plus "Angular Deflection", "Bounding Box", "Deviation", "Draw Style", "Lighting", "Line Color", "Line Width", "Point Color", "Point Size", "Selectable", "Selection Style", "Shape Color", and "Transparency".
Nevertheless, View properties can also be assigned using the view provider object's addProperty()
method.
obj.ViewObject.addProperty("App::PropertyBool", "SuperVisibility", "Base", "Make the object glow")
Source code
In the source code, properties are located in various src/App/Property* files.
They are imported and initialized in src/App/Application.cpp
.
#include "Property.h"
#include "PropertyContainer.h"
#include "PropertyUnits.h"
#include "PropertyFile.h"
#include "PropertyLinks.h"
#include "PropertyPythonObject.h"
#include "PropertyExpressionEngine.h"
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