Package net.sf.saxon.functions.registry

## Interface ExtensionFunctionFactory

- All Known Implementing Classes:
    `JavaExtensionFunctionFactory`

      public interface ExtensionFunctionFactory

  This is a marker interface representing an abstract superclass of JavaExtensionFunctionFactory and DotNetExtensionFunctionFactory. These play equivalent roles in the system: that is, they are responsible for determining how the QNames of extension functions are bound to concrete implementation classes; but they do not share the same interface.

  This interface was introduced in Saxon 8.9. Prior to that, `ExtensionFunctionFactory` was a concrete class - the class now named `JavaExtensionFunctionFactory`.