Creating an Empty Class or Extending from an Existing Class

You can create a Modelica class and define its class type (package, model, component...) in a functional or logical behavior or in a behavior library.

This task shows you how to:

See Also
About Dymola Behavior Modeling
About Modelica Classes
About Creating a Class

Create a New Class or Extend from an Existing Class Using the New Class Command

You can create a new class, either by creating an empty class or by extending an existing class.

Before you begin: You have to be in a library to create a new class.
Note: As an exception, you can create free-standing models to, for example, test features.

In this scenario, you create a model in a behavior library. You can reuse such classes.

Tip: You can maximize the reuse in two ways, depending on what you want to do - and there is a third alternative without any reuse:
  • If you want to add new components to a class, but leave the original class unchanged as component in the new class, you can extend the original class to a new class. See the second and third topic in this task.
  • If you want to use some objects in a class, but not all, to form a starting point of a new class, you can use the Split Model command. See Splitting a Model.
  • If you want to create a new class from an existing class but be free to change any component in the new class without changing the original class, you can create a new class by duplicating an existing class. You can do this by the contextual command Duplicate Class. For more information, see Duplicating a Class.

  1. From the Behavior Authoring section of the action bar, click New Modelica Class .

    Tip: This command is also available from any of:
    • The context menu of a selected class, in the Package Browser, the Preferred Classes Browser, or the Classes for Force Elements browser.
    • The Action Pad panel. To access the Action Pad panel, from the Tools section of the action bar, click Action Pad , or right-click an empty area and select Display > Action Pad.

    The New Class dialog box appears.
  2. From the Name box, enter a valid Modelica name for this new class, in this example enter MyModel.

    Warning: Do not use the following names:
    • PLMInterface
    • PLMConnectors

    These names are reserved for packages automatically created in functional or logical behaviors (for ports-mapping purpose).

  3. From the Class type list, select the class type. By default, this Model type is selected.

    You have the following alternatives:

    • Block
    • Connector
    • Expandable Connector
    • Function
    • Model
    • Package
    • Record
    • Type
    For this scenario, keep the default selection Model.

    Important: In general, try to reuse rather than creating from scratch. For example, it is uncommon, except for library developers, to create connectors from scratch, since there are numerous connectors available in the libraries. You can use them directly or extend them.

    Tip: You can specify the dialog box to remember your selection the next time you create a class. You can do this by selecting the Remember class type attribute option from Me > Preferences > App Preferences > 3D Modeling > Systems Modeling and Execution > Dymola Behavior Modeling , the Editor tab. The default value otherwise is Model.

  4. Click the Insert in box, then select a library from the Package Browser.

    To create a class as top-level class, do not enter a class name in the box.

    Tips:
    • You can make your selection from the Package Browser before launching the New Class command. Your selection is displayed from the Insert in input box but can still be modified.
    • You can select the class in a number of ways, including searching for it; see Using the Class Selector Field.
    • You can specify the dialog box to remember your selection the next time you create a class by selecting the Remember class insert in attribute option from Me > Preferences > App Preferences > 3D Modeling > Systems Modeling and Execution > Dymola Behavior Modeling , the Editor tab. The default value otherwise the activated class. The remembered attribute is not used if a class is selected or the command is used from the context menu; then this class is pre-filled.

    Warning: When creating a class in a behavior, you cannot insert a class in these two packages:
    • PLMInterface
    • PLMConnectors

    These packages are created along with a new functional or logical behavior and are reserved for ports-mapping purpose.

  5. If you need to create a partial class, select the Partial option.

    Tips:
    • If you want to extend from the present class, it is more convenient to use the contextual command Extend from....
    • You can specify the dialog box to remember your selection the next time you create a class by selecting the Remember partial attribute option from Me > Preferences > App Preferences > 3D Modeling > Systems Modeling and Execution > Dymola Behavior Modeling , the Editor tab. The default value otherwise is that the class is not partial.

  6. If you need to create an extended class:
    1. Click the Extends box.

      Tip: This command is also available from the context menu of a selected class, in the Package Browser.

    2. Select a class from the Package Browser or click Switch between class and basic type selection to select a basic type or one of the recent classes from the list.

      Tips:
      • You can select the class in a number of ways, including searching for it; see Using the Class Selector Field.
      • For expert users, if you want to extend a class to another type, extending from the present class gives more choices. See next section.
      • You can specify the dialog box to remember your selection the next time you create a class by selecting the Remember class extends attribute option from Me > Preferences > App Preferences > 3D Modeling > Systems Modeling and Execution > Dymola Behavior Modeling , the Editor tab.

  7. Click OK to close the New Class dialog box and create your new class.
    From the Package Browser, a new class is created under the library node.

In the new class, you can, for example:

Extend from the Present Class

You can create a new class by extending from the present class.

Tip: If you want to create a new class from an existing class but be free to change any component in the new class without changing the original class, you can create a new class by duplicating an existing class. You can do this by the contextual command Duplicate Class. For more information, see Duplicating a Class.

  1. Right-click the class you want to extend from, in the Package Browser, in the Preferred Classes Browser, or in the Classes for Force Elements browser.
  2. From the context menu, select Extend from... .
    The New Class dialog box appears, the boxes corresponding to extending the present class are filled in.
  3. From the Name box, enter a valid Modelica name for this new class.

    Warning: Do not use the following names:
    • PLMInterface
    • PLMConnectors

    These names are reserved for packages automatically created in functional or logical behaviors (for ports-mapping purpose).

  4. Optional: For expert users, you can change the class type: From the Class type list, select the type.

    For information about changing class type when extending, see Modelica Language Specification. This document is available on http://www.modelica.org.

  5. Optional: You can change where to insert the new class: Click the Insert in box, then select a library from the Package Browser.

    To create the class as top-level class, do not enter a class name in the box.

    Tips:
    • You can select the class in a number of ways, including searching for it; see Using the Class Selector Field.
    • The default value is the activated class.

    Warning: When creating a class in a behavior, you cannot insert a class in these two packages:
    • PLMInterface
    • PLMConnectors

    These packages are created along with a new functional or logical behavior and are reserved for ports-mapping purpose.

  6. If you need to create a partial class, select the Partial option.
  7. Click OK to close the New Class dialog box and create your new class.
    From the Package Browser, a new class is created under the library node.

Extend from a Replaceable Component

You can select a replaceable component and create a new class by extending the extending clause class of the replaceable component.

  1. Right-click the replaceable component and select Extend from... .
    The New Class dialog box appears, with some boxes prefilled by default.

    Comparing with the result of step 1 in the first task above, the Extends: box is prefilled with the constraining clause class of the replaceable component, and the Insert in: box is prefilled with the present active class.

  2. See step 3-7 in the previous task.