Defining the Template Properties

Each property represents an ‘attribute’ of the template which is to be adjusted by reference to the parameterized rules when used in a design instance. In the current example, we need to define five properties corresponding to the following dimensions:

The template properties are stored in Design Data (DDAT) elements, owned by a Design Dataset (DDSE), which is itself owned by the TMPL element. When we created the template, we created an empty Design Dataset by setting the Add Properties button to On in Step 2 of Event-driven Graphics Mode.

Exercise continues:

1. Check that the selected element in the Template Browser is the TMPL and then select Modify > Property Definitions you will see a Define Template Properties form which lets you set up the required list of properties.

   The upper part of the form lets you specify the details for a single property, while the lower part displays a list of all of the properties which are currently defined. The list is empty at this stage.

2. Define the first property as follows:

   • Enter the Description as Overall length and the Key as LENG.

   • The Definition option specifies how the value of the property will be derived when the template is used in a design. The choices are:

     Design Parameter	Value taken from design data entered when template is instanced
     Attribute	Value taken from named attribute (Short Key is set to attribute name)
     Expression	Value is result of evaluating expression (as typed into text-box immediately below the option list)
     Plotfile	Name of plotfile to be displayed
     Specification Ref	Allows SpecRef (for example, Profile) to be set
     Sub Element Ref	Allows pointer to subsidiary element (for example, Sub-Equipment) to be set when template is instanced

3. We will set the first four dimensional properties as Design Parameters, so select this option for the Definition field. In the No text-box, enter 1 for the first design parameter.

   • Set the Data Type option to Distance.

   • The Default text-box lets you specify the value which will be used if the correct value cannot be derived at any intermediate stage of the design process. Enter a default length of 1500.

   • The Range text-boxes let you specify acceptable minimum (From) and maximum (To) values for the property value which can be entered in the design. Leave these unset. (Ignore the greyed-out Display button for now.)

     The settings should now look like this:

     

4. Click the Include button to create the currently defined property in the list (there is no separate Apply button on this form).

5. Repeat the process to add the following property definitions to the list:

   Description	Key	DesParNo	Default Distance
   Overall width	WIDT	2	750
   Kickplate height	HEIG	3	300
   Wall thickness	WTHK	4	50

   (You will notice that the application adds parentheses round the default value automatically. It is optional whether or not you enter these when you type in the default value.)

6. The fifth property, namely the thickness of the panel which the second NBOX is to penetrate, will be derived from the actual panel thickness as defined in the design. To achieve this, we will define the property as an expression which represents this thickness.

7. Enter the Description as Panel thickness and the Key as PTHK.

8. Set the Definition option to Expression and type the following expression into the expr text-box:

   HEIG of PLOO 1 of PANEL

   (since the panel thickness is represented by the Height attribute of the Panel Loop element owned by the Panel).

9. Set the Default Distance to 100. Leave the Range limits unset.

   Notice that the Display button is now selected. Its setting determines whether or not the value of this property will be shown on the data-entry form when the template is instanced in a design. Leave the button selected. (The property value will be shown for reference only, since it is derived automatically via the expression and cannot be set explicitly by the designer.)

   The final Currently Defined Properties list should look like this:

   

10. Click the button to remove the form.