Welcome to OStack Knowledge Sharing Community for programmer and developer-Open, Learning and Share
Welcome To Ask or Share your Answers For Others

Categories

0 votes
585 views
in Technique[技术] by (71.8m points)

clojure - How to make a record from a sequence of values

I have a simple record definition, for example

(defrecord User [name email place])

What is the best way to make a record having it's values in a sequence

(def my-values ["John" "[email protected]" "Dreamland"])

I hoped for something like

(apply User. my-values)

but that won't work. I ended up doing:

(defn make-user [v]
  (User. (nth v 0) (nth v 1) (nth v 2)))

But I'm sensing there is some better way for achieving this...

See Question&Answers more detail:os

与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
Welcome To Ask or Share your Answers For Others

1 Answer

0 votes
by (71.8m points)

the defrecord function creates a compiled class with some immutable fields in it. it's not a proper clojure functions (ie: not a class that implements iFn). If you want to call it's constructor with apply (which expects an iFun) you need to wrap it in an anonymous function so apply will be able to digest it.

(apply #(User. %1 %2 %3 %4) my-values)

it's closer to what you started with though your approach of defining a constructor with a good descriptive name has its own charm :)

from the API:

Note that method bodies are
not closures, the local environment includes only the named fields,
and those fields can be accessed directy.

与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
Welcome to OStack Knowledge Sharing Community for programmer and developer-Open, Learning and Share
Click Here to Ask a Question

...