• extension id --> operations


The extension keyword marks a rule as an extension point of the current ruleset (i.e. the cga file).

Similarly to attributes, extension rules can be redefined in an import statement. See the import page for detailed information (syntax 6) and examples.

If an extension point should not generate anything by default, just use one NIL operation:

extension Rule --> NIL

Extension rules cannot be defined in styles other than the Default style.


Redefine an extension rule

// rule.cga

extension Roof(angle) --> roofHip(angle)

Init --> Roof(22)

c// main.cga

import rule : "rule.cga"( Roof(angle) --> roofGable(angle) )

Lot --> rule.Init

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