refer
- (refer ns-sym & filters)
refers to all public vars of ns, subject to filters. filters can include at most one each of: :exclude list-of-symbols :only list-of-symbols :rename map-of-fromsymbol-tosymbol For each public interned var in the namespace named by the symbol, adds a mapping from the name of the var to the var to the current namespace. Throws an exception if name is already mapped to something else in the current namespace. Filters can be used to select a subset, via inclusion or exclusion, or to provide a mapping to a symbol different from the var's name, in order to prevent clashes. Use :use in the ns macro in preference to calling this directly.
© Rich Hickey. All rights reserved. Eclipse Public License 1.0
3 Examples
user=> (refer 'clojure.string :only '[capitalize trim]) nil user=> (capitalize (trim " hOnduRAS ")) "Honduras"
user=> (refer 'clojure.string :rename '{capitalize cap, trim trm}) WARNING: replace already refers to: #'clojure.core/replace in namespace: user, being replaced by: #'clojure.string/replace WARNING: reverse already refers to: #'clojure.core/reverse in namespace: user, being replaced by: #'clojure.string/reverse nil user=> (cap (trm " hOnduRAS ")) "Honduras" user=> (join \, [1 2 3]) "1,2,3"
;;; `:only' accepts only original names. ;; wrong user=> (refer 'clojure.string :rename '{capitalize cap, trim trm} :only '[cap trm]) IllegalAccessError cap does not exist clojure.core/refer (core.clj:3849) ;; right user=> (refer 'clojure.string :rename '{capitalize cap, trim trm} :only '[capitalize trim]) nil ;; work well user=> (cap (trm " hOnduRAS ")) "Honduras" ;; and also, cannot use either of them. user=> (join \, [1 2 3]) CompilerException java.lang.RuntimeException: Unable to resolve symbol: join in this context, compiling:(NO_SOURCE_PATH:1:1)
1 Note
By 
, created 2.3 years ago
, created 2.3 years agoWarning: the referral of a var isn't transitive.
refer only works with a var's original namespace.
If you refer A/foo from B, you can't then refer B/foo from C.
foo it will appear in B's ns-map, but not ns-publics or ns-interns, unintuitively.