Define Data Classes - MATLAB & Simulink (original) (raw)

This example shows how to subclass Simulink® data classes.

Use MATLAB® class syntax to create a data class in a package. Optionally, assign properties to the data class and define storage classes.

• Use an example to define data classes
• Manually define data class
• Optional: Add properties to data class
• Optional: Add initialization code to data class
• Optional: Define storage classes
• Optional: Define custom attributes for storage classes

Use an example to define data classes

1. In the working folder, view the +SimulinkDemos data class package in the folder dataclasses.
2. Copy the folder to the location where you want to define your data classes.
3. Rename the folder +mypkg and add its parent folder to the MATLAB path.
4. Modify the data class definitions.

Manually define data class

1. Create a package folder +mypkg and add its parent folder to the MATLAB path.
2. Create class folders @Parameter and @Signal inside +mypkg.
   Note
   Simulink requires data classes to be defined inside+Package/@Class folders.
3. In the @Parameter folder, create a MATLAB file Parameter.m and open it for editing.
4. Define a data class that is a subclass of Simulink.Parameter using MATLAB class syntax.
   classdef Parameter < Simulink.Parameter

end % classdef

To use a custom class name other than Parameter orSignal, name the class folders using the custom name. For example, to define a class mypkg.myParameter:

• Define the data class as a subclass of Simulink.Parameter orSimulink.Signal.
  classdef myParameter < Simulink.Parameter

end % classdef

• In the class definition, name the constructor method asmyParameter or mySignal.
• Name the class folder, which contains the class definition, as@myParameter or @mySignal.

Optional: Add properties to data class

The properties and end keywords enclose a property definition block.

classdef Parameter < Simulink.Parameter properties % Unconstrained property type Prop1 = []; end

properties(PropertyType = 'logical scalar')
    Prop2 = false;
end

properties(PropertyType = 'char')
    Prop3 = '';
end

properties(PropertyType = 'char',...
  AllowedValues = {'red'; 'green'; 'blue'})
    Prop4 = 'red';
end

end % classdef

If you add properties to a subclass of Simulink.Parameter,Simulink.Signal, or Simulink.CustomStorageClassAttributes, you can specify the following property types.

If you add a property that requires special copy behavior, you define that behavior by overriding the copyElement method. For example, in the +SimulinkDemos data class package, the class definition fileParameter.m defines the propertyGenericProperty with an unconstrained property type. ThecopyElement method specifies the copy behavior forGenericProperty. When you add, remove, or change a property that requires special copy behavior, you must also be sure to update thecopyElement method.

If you use MATLAB property validation (see Validate Property Values) instead of PropertyType, the properties are displayed as an edit field in the property dialog box of the class. If you use PropertyType and AllowedValues, then the property dialog box displays:

• A check box for logical scalar properties.
• A dropdown menu for character vectors and AllowedValues.

Optional: Add initialization code to data class

You can add a constructor within your data class to perform initialization activities when the class is instantiated. The added constructor cannot require an input argument.

In this example, the constructor initializes the value of object obj based on an optional input argument.

classdef Parameter < Simulink.Parameter methods function obj = Parameter(optionalValue) if (nargin == 1) obj.Value = optionalValue; end end end % methods end % classdef

Optional: Define storage classes

Use the setupCoderInfo method to configure theCoderInfo object of your class. Then, create a call to theuseLocalCustomStorageClasses method and open the Custom Storage Class Designer.

1. In the constructor within your data class, call theuseLocalCustomStorageClasses method.
   classdef Parameter < Simulink.Parameter
   methods
   function setupCoderInfo(obj)
   useLocalCustomStorageClasses(obj, 'mypkg');
   
   obj.CoderInfo.StorageClass = 'Custom';
   end
   end % methods

end % classdef 2. Open the Custom Storage Class Designer for your package. 3. Define storage classes.

Optional: Define custom attributes for storage classes

1. Create a MATLAB file myCustomAttribs.m and open it for editing. Save this file in the +mypkg/@myCustomAttribsfolder, where+mypkg is the folder containing the @Parameter and @Signal folders.
2. Define a subclass of Simulink.CustomStorageClassAttributes using MATLAB class syntax. For example, consider a storage class that defines data using the original identifier but also provides an alternate name for the data in generated code.
   classdef myCustomAttribs < Simulink.CustomStorageClassAttributes
   properties(PropertyType = 'char')
   AlternateName = '';
   end
   end % classdef
3. Override the default implementation of the isAddressable method to determine whether the storage class is writable.
   classdef myCustomAttribs < Simulink.CustomStorageClassAttributes
   properties(PropertyType = 'logical scalar')
   IsAlternateNameInstanceSpecific = true;
   end
   
   methods
   function retVal = isAddressable(hObj, hCSCDefn, hData)
   retVal = false;
   end
   end % methods

end % classdef 4. Override the default implementation of thegetInstanceSpecificProps method.
For example, see these override functions:
function props = getInstanceSpecificProps(hObj)
% GETINSTANCESPECIFICPROPERTIES Return instance-specific properties
% (custom attributes that can be modified on each data object).

  if hObj.IsStructNameInstanceSpecific  
    props = findprop(hObj, 'StructName');  
  else  
    props = [];  
  end  
end  

function props = getInstanceSpecificProps(hObj)
% GETINSTANCESPECIFICPROPERTIES Return instance-specific properties
% (custom attributes that can be modified on each data object).
props = [];

  if hObj.IsOwnerInstanceSpecific  
      ptmp = findprop(hObj, 'Owner');  
      props = [props; ptmp];  
  end  
    
  if hObj.IsDefinitionFileInstanceSpecific  
      ptmp = findprop(hObj, 'DefinitionFile');  
      props = [props; ptmp];  
  end  
    
  if hObj.IsPersistenceLevelInstanceSpecific  
      ptmp = findprop(hObj, 'PersistenceLevel');  
      props = [props; ptmp];  
  end  
end  

Note
This is an optional step. By default, all custom attributes are instance-specific and are modifiable for each data object. However, you can limit which properties are allowed to be instance-specific. 5. Override the default implementation of thegetIdentifiersForInstance method to define identifiers for objects of the data class.
Note
In its default implementation, this method queries the name or identifier of the data object and uses that identifier in generated code. By overriding this method, you can control the identifier of your data objects in generated code.
classdef myCustomAttribs < Simulink.CustomStorageClassAttributes
properties(PropertyType = 'char')
GetFunction = '';
SetFunction = '';
end

methods  
    function retVal = getIdentifiersForInstance(hCSCAttrib,...  

hCSCDefn, hData, identifier)
retVal = struct('GetFunction',...
hData.CoderInfo.CustomAttributes.GetFunction, ...
'SetFunction', hData.CoderInfo.CustomAttributes.SetFunction);
end%
end % methods
end % classdef 6. If you are using grouped storage classes, override the default implementation of thegetIdentifiersForGroup method to specify the identifier for the group in generated code.
For an example, in the working folder, seeCSCTypeAttributes_FlatStructure.m in the folder@CSCTypeAttributes_FlatStructure.

See Also

Topics

• Data Objects