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This is the expression node. It takes an arbitrary list of doubles as input and performs any legal MEL expression on them to generate a list of double outputs.

Caution: Use of the 'setAttr' or 'getAttr' statements from within an expression node can have unexpected results. Using these statements bypasses the normal dependency graph evaluation mechanism and may cause incorrect or incomplete evaluation.
Node name Parents MFn type Compatible function sets
expression node kExpression kBase
kNamedObject
kDependencyNode
kExpression

Related nodes

animCurve, animCurveUT, animCurveUU, animCurveUA, animCurveTT, animCurveTU, animCurveUL, resultCurve, resultCurveTimeToLinear, resultCurveTimeToTime, resultCurveTimeToUnitless, resultCurveTimeToAngular, animCurveTA, animCurveTL, animBlend, animBlendInOut

Attributes (15)

animated, attribute, evaluateNow, exprConnCount, expression, frame, input, internalExpression, lastTimeEvaluated, newFileFormat, object, objectMsg, output, time, unitOption

Long name (short name) Type Default Flags
input (in) double 0.0 arrayoutputinputconnectablestorable
This is the multi that holds the connection as input into the expression.
output (out) double 0.0 arrayoutputinputconnectable
This is the multi that holds the connection as output of the expression.
object (ob) string NULL outputconnectablehidden
Default object for attribute names in expression.
attribute (a) string NULL outputinputconnectablehidden
Default attribute if no lvalue in expression
expression (e) string NULL outputinputconnectablehidden
Evaluated value of the expression
exprConnCount (xcc) integer 0 outputconnectablehidden
number of input and output connections for expressions
internalExpression (ixp) string NULL outputinputconnectablestorablehidden
This is the internal representation for the expression.
time (tim) time 0film outputinputconnectablehidden
This holds the value for time to be queried in seconds.
frame (frm) time 0film outputinputconnectablehidden
This holds the value for time to be queried in frames.
lastTimeEvaluated (lte) time 0film outputinputconnectablehidden
The last time that this expression was evaluated.
evaluateNow (xen) short 0 outputconnectablehidden
This attribute depends on aTime. Dirtying aTime and asking for this will force evaluation.
animated (ani) enum 1 outputinputconnectablestorablehidden
This attribute tells whether or not the expression node was forced to be "animated" from the expression command. Records the unit conversion option used to create/edit this expression.
newFileFormat (nff) short 0 outputconnectablehidden
Obsolete.
objectMsg (obm) Message n/a outputinputconnectablehidden
Identifies the default object.
unitOption (uno) enum 0 outputinputconnectablestorablehidden
Records the unit conversion option used to create/edit this expression.