This information is part of the Modelica Standard Library maintained by the Modelica Association.
Annotation for code generation (evaluate parameter value)
annotation"(" Evaluate "=" ( false | true ) ")
The annotation Evaluate can occur in the component declaration, its type declaration, or a base-class of the type-declaration.
In the case of multiple conflicting annotations it is handled similarly to modifiers (e.g., an Evaluate-annotation on the component declaration takes precedence).
The annotation Evaluate only has effect for a component declared with the prefix
If Evaluate = true, the model developer proposes to utilize the value for the symbolic processing. In that case, it is not possible to change the parameter value after symbolic pre-processing.
If Evaluate = false, the model developer proposes to not utilize the value of the corresponding parameter for the symbolic processing.
Evaluate is for example used for axis of rotation parameters in the Modelica.Mechanics.MultiBody library in order to improve the efficiency of the generated code