Defining a Template Rule

So far, we have simply defined the properties of the template which must have their values set when the template is instanced in a design. We must now define the rules which define how the geometry of the template instance is to be parameterized in terms of those properties.

Exercise continues:

1. Check that you are still at the TMPL in the Template Browser and then select Modify > Parameterization. You will see a Template Member Parameters form listing the primitives which make up the current template.

2. In the Template Members list, select the BOX. Notice how the Rules list automatically shows those attributes of the selected element for which you can set rules.

3. In the Rules list, select X length. You will see an Attribute Rule (X length) form ready to accept data relevant to the selected type of attribute. In the Expression text-box, enter the following expression:

   CDPR LENG

   This means: ‘Set the X-length to the value of that property of the current template whose key is LENG’ (as defined in Step 1 of Defining the Template Properties). This expression will be explained more fully in the next section.

   To see the effect of this rule, click the Text Expression button and study the result. Because no real design data has yet been created, the X length of the box has been set by the rule using the default value of the LENG property (which we specified as 1500).

4. Click OK to accept the rule. Notice how it is now shown in the Rules list on the Template Member Parameters form.