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Modification Prefix Replaceable and Redeclare

1 Replaceable

A declared element of a class must have the prefix replaceable in order to be redeclared, apart from redeclarations that only change the attribute value and/or restricts the variability and possibly the dimension sizes. The main motivation for this rule is that a class needs to be designed for inheritance that includes redeclaration. Otherwise unexpected errors may occur.


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class MicroCircuit
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  replaceable Resistor R1 (R = 4.0);
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end MicroCircuit;
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​

2 Connector Classes

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type Voltage = Real(unit = "V");
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​

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type Current = Real(unit = "A");
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​

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connector Pin
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  Voltage     v;
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  flow Current   i;
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end Pin;
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​

3 Resistor and TempResistor

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model Resistor
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  Pin       p, n                "Positive and Negative Pins";
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  Voltage     v;
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  Current     i;
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  parameter Real R(unit = "Ohm")          "Resistance";
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equation
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  v = R*i;
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end Resistor;
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​

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model TempResistor                  "Temperature dependent Resistor"
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  Pin       p, n                "Positive and Negative Pins";
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  Voltage     v;
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  Current     i;
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  parameter Real R(unit = "Ohm")          "Resistance at reference Temperature";
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  parameter Real RT(unit = "Ohm/degC")   = 0     "Temperature dependent Resistance";
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  parameter Real Tref(unit = "degC")   = 20    "Reference Temperature";
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  Real        Temp           = 20    "Actual Temperature";
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equation
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  v = i*(R + RT*(Temp - Tref));
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end TempResistor;
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​

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model SuperTempResistor                "Temperature dependent Resistor"
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  Pin       p, n                "Positive and Negative Pins";
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  Voltage     v;
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  Current     i;
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  parameter Real R(unit = "Ohm")          "Resistance at reference Temperature";
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  parameter Real RT(unit = "Ohm/degC")   = 0     "Temperature dependent Resistance";
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  parameter Real Tref(unit = "degC")   = 20    "Reference Temperature";
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  Real        Temp           = 20    "Actual Temperature";
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  parameter Boolean Super         = true;
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equation
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  v = i*(R + RT*(Temp - Tref));
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end SuperTempResistor;
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​

4 Redeclare

The redeclare prefix is used at the front of a modifier containing a new variable or type declaration that replaces the original variable or type declaration element in the modified class.The reason for requiring a special keyword like redeclare is to reduce the risk for accidental programming errors that otherwise might occur when whole declarations are replaced by declarations of different types.


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class TempMicroCiruit = MicroCircuit(redeclare TempResistor R1);
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​


In order to allow further redeclaration of a redeclared element the replaceable prefix should be present also in the modifier.


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class TempMicroCiruit2 = MicroCircuit(redeclare replaceable TempResistor R1);
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​


In the class SuperTempMicroCircuit the keyword replaceable is left out, which means that no further redeclaration is possible.


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class SuperTempMicroCiruit = TempMicroCiruit2(redeclare SuperTempResistor R1);
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​

4.1 Flattening of MicroCircuit, TempMicroCiruit2

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instantiateModel(MicroCircuit)
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​

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instantiateModel(TempMicroCiruit2)
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​

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instantiateModel(SuperTempMicroCiruit)
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​