SAS/AF Software: Class Dictionary

Using the External File Model Class

If you want to expand the functionality of the external file model, subclass it directly and override the methods you want to modify.

If you are making a model to view data other than catalog entries or external files, subclass the Text Model Template class. In this case, define all of the methods for the class to provide the functionality specific to your data. For an example of creating a new model by subclassing the Text Model Template class, see that class.

Subclassing the External File Model

This example creates a model subclass of the external file model that, when connected with a text viewer, adds the word "Line" followed by the line number to the beginning of each text line:

Create the CLASS entry.
- Open a new CLASS entry to be used as the model class by entering this command:
```
build sasuser.textview.filesub.class
```
  FILESUB.CLASS is the name of the external file model subclass. Set the parent class to SASHELP.FSP.EXFILEDE, the name of the External File Model class. FILESUB.CLASS will inherit methods from EXFILEDE.CLASS.
Override the external file model methods.
- In Additional Attributes, select Methods to bring up a list of all of the methods defined for this class. For this example you only need to override the _getData method.
- Select the _getData method. In the Source Entry field specify SASUSER.TEXTVIEW.FILESUB.SCL as the location for the new SCL code for the method.
- Specify GETDATA as the SCL entry label.
- Select OK to exit the Methods window.
Provide the SCL code for the external file model methods.
- To open the SCL entry defined in step 2 as the _getData method source, enter this command:
```
build sasuser.textview.filesub.scl
```
- Enter the following code:
```
GETDATA: method buffer attr $ 200 maxlen
         row col 8 cchar $ 1
                rc textlist attrlist 8;
call super(_self_, '_get_data_', buffer,
            attr, maxlen, row, col,
           cchar, rc, textlist, attrlist);
buffer = "Line " || row || " " || buffer;
endmethod;
```
  The _getData method calls the external file model's _getData method to get its usual functionality and then modifies the returned text string with the line number information.
- Compile and save the SCL entry.
Use the new external file model.
- Open a frame in the same catalog and make a text viewer by entering the command
```
rm make 'text viewer'
```
- In Data Source, select Other and in the field to the right enter in the name of the new class, SASUSER.TEXTVIEW.FILESUB.CLASS. Press RETURN.
- In Additional Attributes, select Data class attributes to select a file to view. Select OK to close the External File Attributes window and again to close the Text Viewer Attributes window.
The file appears with the line number information.

For an additional example of subclassing a model, see the Text Model Template class.

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