Expression

An expression allows values and formulas to be captured, modified and referenced. Expressions allow the creation and manipulation of parametric relationships.

The expression must be a number, and the application must create and set a number-valued expression into the block during the initialize callback.

Note: The Expression block works only with an expression of type Number.

This is what differentiates it from the plain Double block: it creates an expression parameter which can be linked to other expressions or measurements, and gives access to the Expression Editor through the DesignLogic presentation.

Inherited general properties

• BlockID
• Enable
• Group
• Label
• Show
• Expanded

Block-specific properties

Property Name	Description	Access	Property Type	List of Values
BalloonTooltipText / BalloonTooltipImage / BalloonTooltipLayout	Standard balloon tooltip text/image/layout properties (see other blocks for full value lists).	CIGS	String/String/Enum	—
Dimensionality	Specifies the type of quantity that the expression represents (e.g., Length, Angle, Energy). Determines the set of unit options available for the quantity (e.g., for Length: mm, in; for Angle: degrees, radians).	CIG	Enum	Any value in the Dimensionality enumeration.
ExpressionObject	Specifies the Expression object tied to the block. User inputs to the block are written to the Expression object.	IG	TaggedObject	Object of type NXOpen.Expression.
Formula	Specifies the formula for the expression, e.g. sin(30).	CSG	String	Any string representing a valid formula.
HasUnitsMenu	Relevant only when Dimensionality is set to a value that has units. Specifies whether to show a menu that permits the user to change units.	CIG	Logical	True — shows the units menu. False — does not show it.
Units	An object representing the units for the expression.	I	TaggedObject	Object of type NXOpen.Unit.
Value	Specifies the expression value. Note: When Dimensionality is set to a unit, accessing Value through automation always returns the value in base part units, irrespective of the display units. Example: if the base part is metric and the Expression block's display unit is tonne (t), entering 50 into the block returns 50000 via automation (i.e., in kilograms).	CSG	Double	Any value.
WithScale	Specifies whether the slider bar is available on the block.	CIG	Logical	True — shows the slider bar. False — hides the slider bar.
LimitCheckTolerance	Specifies the tolerance value used when checking limits for MaximumValue/MinimumValue equality.	CSG	Double	Any value >= 0.0 used to determine equality with the limits. Any value < 0.0 means the system default tolerance is used (default is -1).
MaximumValue	Specifies the maximum allowed value. Values greater than this are invalid; equal is valid if MaxInclusive is True.	CSG	Double	Any value.
MaxInclusive (inferred pairing, consistent with Integer/Double blocks)	See MaximumValue.	SG	Logical	TRUE/FALSE.
MinimumValue	(Analogous minimum-value property; documented alongside MinInclusive below.)	CSG	Double	Any Double value.
MinInclusive	See MinimumValue.	CSG	Logical	True — an input value exactly equal to the minimum is valid. False — it is invalid.
PageIncrement	Specifies the value by which to increment the scale when pressing Page Up/Page Down.	CSG	Double	Any integer value less than MaximumValue.
LineIncrement	Specifies the value by which to increment the scale when pressing the Left/Right arrow keys.	CSG	Double	Any integer value less than MaximumValue.
AdaptiveScaleLimits	Specifies whether the scale should be adaptive.	CSG	Logical	TRUE — use Adaptive Scale. FALSE — do not use Adaptive Scale.
RetainValue	Determines if the block's value is saved in dialog memory (upon OK, Apply, or Close).	CSG	Logical	TRUE — retains the previous value. FALSE — does not retain.
RetainUnits	Determines if the block's units are saved in dialog memory (upon OK, Apply, or Close).	CSG	Logical	TRUE — retains the previous unit. FALSE — does not retain.

Access column legend

Character	Stands for	Meaning
C	Creation	Modifiable interactively in Block UI Styler at design time.
I	Initialize	Modifiable at run time via NXOpen API, but only during the Initialize callback.
G	Get	Readable via NXOpen API in any callback.
S	Set	Modifiable at run time via NXOpen API in any callback.

Related Numbers blocks

Integer, Double, Linear Dimension, Angular Dimension, Radius Dimension, On Path Dimension, Integer Table, Double Table.

Linear Dimension, Angular Dimension, and Radius Dimension are all special cases of the Expression block (their Dimensionality is fixed to linear length, angular, and radius respectively).