methodical.impl.dispatcher.common — methodical 0.11.4

Utility functions for implementing Dispatchers.

add-preference clj

(add-preference isa?* prefs x y)

Add a method preference to prefs for dispatch value x over y. Used to implement prefer-method. isa?* is used to determine whether a relationship between x and y that precludes this preference already exists; it can be clojure.core/isa?, perhaps partially bound with a hierarchy, or some other 2-arg predicate function.

ambiguous? clj

(ambiguous? hierarchy prefs dispatch-value dispatch-val-x dispatch-val-y)

True if neither dispatch-val-x nor dispatch-val-y dominate one another, e.g. because they are the same value or are both equally-specific ancestors.

distinct-by clj

(distinct-by f coll)

Like distinct, but uses value of (f item) to determine whether to keep each item in the resulting collection.

dominates? clj

(dominates? hierarchy prefs x y)

(dominates? hierarchy prefs default-dispatch-value x y)

True if dispatch value x should be considered more specific for purposes of method combination over dispatch value y, e.g. because x derives from y, or because x (or one of its ancestors) has been explicitly preferred over y (or one of its ancestors).

4-arity version does not take the default-dispatch-value into account, but 5-arity version does.

domination-comparitor clj

(domination-comparitor dominates?-pred)

(domination-comparitor hierarchy prefs)

(domination-comparitor hierarchy prefs dispatch-value)

Given a hierarchy and prefs return a function that can be used to sort dispatch values from most-specific to least-specific.

prefers? clj

(prefers? hierarchy prefs x y)

True if x or one of its ancestors is prefered over y or one of its ancestors.