Button Type Precedence

Explicit buttons always take precedence over implicit buttons. Thus, if a button selection is made which falls within both an explicit and implicit button, only the explicit button will be selected. Explicit button labels are not allowed to overlap; Hyperbole’s behavior in such cases is undefined.

If there is no explicit button at point during a selection request, then each implicit button type predicate is tested in turn until one returns non-nil or all are exhausted. Since two implicit button types may have overlapping domains, those contexts in which their predicates are true, only the first matching type is used. The type predicates are tested in reverse order of definition, i.e. most recently entered types are tested first, so that personal types defined after standard system types take precedence. It is important to keep this order in mind when defining new implicit button types. By making match predicates as specific as possible, one can minimize any overlapping implicit button domains.

Once a type name is defined, its precedence relative to other types remains the same even if its body is redefined, as long as its name is not changed. This allows incremental modifications to types without any worry of altering their precedences. See Creating Types, for information on how to develop or modify types.