Redeclarations of Annotation Choices

The user interface can suggest reasonable redeclarations, where the string comment in the choice declaration can be used as a textual explanation of a choice. Based on the interactions with the user, the GUI then generates the appropriate Modelica code. The annotation can also be used as a hint to the user doing textual Modelica programming. In order to support this mode of operation, an annotation called choices containing choice elements is predefined to be recognized with certain semantics in Modelica, including recognition of redeclaration statements in the annotation.

1 Resistor

2 MyResistor

model ReplResistor replaceable model MyResistor = Resistor annotation(choices( choice(redeclare model MyResistor = lib2.Resistor(a={2})), choice(redeclare model MyResistor = lib2.Resistor) ) ); end ReplResistor;

If the user would choose the first alternative, the following code might be produced if MyResistor is part of the class MyCircuit and the chosen name of the instantiated component is x:

MyCircuit x(redeclare MyResistor=lib2.Resistor(a={2}))

Additional examples of replaceable class declarations with redeclaration choices are shown below.

3 Simulation of ReplResistor

simulate( ReplResistor )

4 Electrical Connectors

connector Pin "Pin of an electrical component" Voltage v "Potential at the pin"; flow Current i "Current flowing into the pin"; end Pin; //From Modelica.Electrical.Analog.Interfaces
connector PositivePin "Positive pin of an electrical component" Voltage v "Potential at the pin"; flow Current i "Current flowing into the pin"; end PositivePin; //From Modelica.Electrical.Analog.Interfaces
connector NegativePin "Negative pin of an electrical component" Voltage v "Potential at the pin"; flow Current i "Current flowing into the pin"; end NegativePin; //From Modelica.Electrical.Analog.Interfaces

5 Electrical Components

partial model TwoPin // Same as OnePort in Modelica.Electrical.Analog.Interfaces "Component with two electrical pins p and n and current i from p to n" Voltage v "Voltage drop between the two pins (= p.v - n.v)"; Current i "Current flowing from pin p to pin n"; PositivePin p; NegativePin n; equation v = p.v - n.v; 0 = p.i + n.i; i = p.i; end TwoPin;

6 Replaceable Resistor

model R replaceable Resistor Load(R=2) extends TwoPin; annotation(choices( choice(redeclare lib2.Resistor Load(a = {2}) ), choice(redeclare Capacitor Load(L = 3) ))); end R;

7 Friction

model Friction // ... end Friction;
model FF replaceable FrictionFunction a(func = exp) extends Friction; annotation(choices( choice(redeclare ConstantFriction a(c = 1) ), choice(redeclare TableFriction a(table = "a") ), choice(redeclare FunctionFriction a(func = exp) ))); end FF;

8 KindOfController

The choices annotation is not restricted to replaceable elements. It is also applicable to nonreplaceable elements, simple variables and types used for enummerations. For example, consider the following Integer type called KindOfController used to represent a choice of controller in the modeling process out of the following enumeration of three recommended alternatives.

type KindOfController = Integer(min=1, max=3) annotation(choices( choice = 1 "P", choice = 2 "PI", choice = 3 "PID"));

Assume that KindOfController is used in a model KindOfControllerInst as below:

model KindOfControllerInst KindOfController x; // Instance of KindOfController end KindOfControllerInst;

An interactive choice of the third alternative from a menu containing the alternatives {"P", "PI", "PID"} would result in the default value 3 for the instatiated variable x in the following code for an instance a2 of the model A.

class KOCInst KindOfControllerInst a2(x = 3 "PID"); end KOCInst;

9 Simulation of KindOfController

simulate( KOCInst )
plot(a2.x)