Evaluates x then calls all of the methods and functions with the
value of x supplied at the front of the given arguments. The forms
are evaluated in order. Returns x.
(doto (new java.util.HashMap) (.put "a" 1) (.put "b" 2))
;; Note that even though println returns nil, doto still returns the date object
user> (doto (java.util.HashMap.)
(.put "a" 1)
(.put "b" 2)
(println :printed))
#<HashMap {b=2, a=1}> :printed
#<HashMap {b=2, a=1}>
;; quick demonstration of using a Collections function on the resulting ArrayList user=> (def al (doto (java.util.ArrayList.) (.add 11) (.add 3)(.add 7))) #'user/al user=> al #<ArrayList [11, 3, 7]> user=> (java.util.Collections/sort al) nil user=> al #<ArrayList [3, 7, 11]> user=>
Source
clojure/core.clj:3395
top
(defmacro doto
"Evaluates x then calls all of the methods and functions with the
value of x supplied at the front of the given arguments. The forms
are evaluated in order. Returns x.
(doto (new java.util.HashMap) (.put \"a\" 1) (.put \"b\" 2))"
{:added "1.0"}
[x & forms]
(let [gx (gensym)]
`(let [~gx ~x]
~@(map (fn [f]
(if (seq? f)
`(~(first f) ~gx ~@(next f))
`(~f ~gx)))
forms)
~gx)))
Comments top
No comments for doto. Log in to add a comment.