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Web Development with Clojure, Third Edition: guestbook.auth functions not invocable (P. 168)

Dmitri Sotnikov @dmitri and Scot Brown @svmbrown

I was trying to execute the following code on p. 168:

user> (in-ns 'guestbook.auth)
#namespace[guestbook.auth]
guestbook.auth> (create-user! “testuser” “testpass”)
1
guestbook.auth> (authenticate-user “testuser” “testpass”)
{:login “testuser”, :created_at #inst “2019-09-20T02:22:53.217-00:00”}
guestbook.auth> (authenticate-user “testuser” “wrongpass”)

but the functions in the guestbook.auth namespace were simply unavailable after I switched to that namespace. I was getting No such var error messages.

After a lot of searching, I stumbled upon this from https://clojure.org/guides/repl/navigating_namespaces

How to make sure a lib is loaded

To make sure that a lib with namespace mylib.ns1 has been loaded in the REPL, you can do any one of the following:

  1. require it directly: (require '[mylib.ns1])
  2. load a namespace which itself requires mylib.ns1 (directly or indirectly).
  3. evaluate manually all the code in the source file mylib.ns1

So I believe this section in the book was too premature. I actually went on to type in the login route code further down on pp. 168-9. Since that login route code loads (a la #2 above) the guestbook.auth namespace, once you jack-in or lein repl you will be able to execute the functions in the guestbook.auth namespace. So I think if the code blocks are reversed, that would help solve this issue.

First Post!

Dmitri

Dmitri

Author of Web Development with Clojure

Yeah, using require would force the namespace to load. Simply doing in-ns will switch to the namespace, but won’t trigger for the functions there to be evaluated. I think you’re right that loading the namespace would be the way to go here to avoid the behavior.

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