====== Set Pipeline Parameter From Expression ======

**Set_Pipeline_Parameter_From_Expression**
/PARAMETER_NAME=t_Mass
/EXPRESSION=METRIC::PROCESSED::HEIGHT * 4.6
/AS_INTEGER=TRUE
**;**
The pipeline parameter contains the value of the expression.

Getting the syntax correct can be challenging because there can be a conflict between the & as a concatenation parameter in a pipeline parameter and the & as a boolean "and" operator.

For many pipeline commands Visual3D recognizes the conflict and handles the situations in a context specific way.

Visual3D cannot make that distinction and "bad" things happen.

Consider the following which uses string comparisons and a pipeline parameter in the expression:

**Set_Pipeline_Parameter_From_Expression**
/PARAMETER_NAME= MVAL
/EXPRESSION=(&::TAG_NAMES& == Utility) * 4.6
/AS_INTEGER=FALSE
**;**
The goal was to set MVAL to 4.6 when the pipeline parameter TAG_NAMES was equal to the string "Utility";

One solution is to separate the pipeline parameter from the expression.

**Set_Pipeline_Parameter**
/PARAMETER_NAME=TEMP
/PARAMETER_VALUE=(&::TAG_NAMES& == Utility)*4.6
**;**
\\


**Set_Pipeline_Parameter_From_Expression**
/PARAMETER_NAME=t_Mass
/EXPRESSION=::TEMP
/AS_INTEGER=FALSE
**;**
\\
Another solution, which is even trickier in terms of syntax is:

**Set_Pipeline_Parameter_From_Expression**
/PARAMETER_NAME=SCOTT
/EXPRESSION=("&::TAG_NAMES&"==" Utility")
! /AS_INTEGER=TRUE
**;**
This forces Visual3D to recognize the strings as strings and the & is treated correctly.

\\


=== Get global metrics ===

Global metrics can be set to a pipeline parameter by setting "GLOBAL" in front of the metric name. More information about expressions can be found [[Visual3D:Documentation:Pipeline:Expressions:Expressions_Overview|here]].

**Set_Pipeline_Parameter_From_Expression**
/PARAMETER_NAME=KATIE
/EXPRESSION=GLOBAL::METRIC::PROCESSED::MASS
/AS_INTEGER=FALSE
**;**