将命名空间的clojure关键字转换为字符串的正确方法是什么？

Question

When the name function is used it correctly returns the name of a keyword as a String, as in:

(name :k) ; => "k"

A problem exists when using name on a namespaced keyword such as:

(name :n/k) ; => "k"

I can use the namespace function to correctly obtain the string I'm looking for:

(str (namespace :n/k) "/" (name :n/k)) ; => "n/k"

But for some reason I feel there should be a better way to obtain the fully qualified string.

What would be the best way to do it?

Answer 1

Your approach is the best way to do it; it's only hard because converting a namespaced keyword to a string is an uncommon goal, and not something you'd expect to do regularly. You could write it without repeating the keyword, if you wanted:

(string/join "/" ((juxt namespace name) k))

Answer 2

Keywords actually store a symbol with the same namespace and name in a public final field and generate their string representations by prepending a colon to the string representation of that symbol. So, we can simply ask the symbol for the same and not prepend the colon:

(str (.-sym :foo/bar))
;= "foo/bar"

Answer 3

(subs (str :foo/k) 1)
;=> "foo/k"

Answer 4

Based on the implementation of name :

user=> (source name)
(defn name
  "Returns the name String of a string, symbol or keyword."
  {:tag String
   :added "1.0"
   :static true}
  [x]
  (if (string? x) x (. ^clojure.lang.Named x (getName))))
nil
user=>

And given that the clojure.lang.Named interface has a getNamespace method:

https://github.com/clojure/clojure/blob/master/src/jvm/clojure/lang/Named.java

So you can do this:

(defn full-name [k] (str (.getNamespace k) "/" (.getName k)))