Hi! Is there a way to add metada to a final Java class? I need to have different cheshire formatters for different instances of a Java class (backwards compatibility).

You can't add metadata to arbitrary Java objects. Only to things that implement clojure.lang.IObj

@seancorfield Thanks for the explanation. I've tried using proxy but that didn't work.

as in

(defn wrap-money
    ([^Money m] (wrap-money m {}))
    ([^Money m _meta]
     (proxy [Money IObj] [(.getAmount m)]
       (meta [] _meta)
       (withMeta [meta'] (wrap-money m meta')))))  

Even if I create a Java wrapper that implements IObj, it's not gonna work because the Money class is final.

There's another interface you need to implement as well, forgot what it is

IMeta maybe?

@didibus will try that, thanks

nope, same error Cannot inherit from final class

Oh, that's different, you can't extend a final class in Java

I'm guessing Money is final?

yep!

All you could do is use composition, make something take a Money inside itself. MoneyWrapper, you can make that a vector, a map, a record, or go for a deftype or a Java class, up to you

But I'm guessing maybe cheshire has another mechanism to pick its formatter, aside from meta?

@didibus I've spent the last hour reading the cheshire docs & source and, to be honest, I think even the meta route wasn't going to work because I don't think Cheshire will pickup the correct superclass.

I really don't want to have to refactor old code, so I've been trying the polymorphism/meta route before a wrapper container.

Clojure protocols can add functionality to existing classes, I believe even final ones, only for Clojure protocol functions. Not sure whether Cheshire has any protocols you can extend in its implementation

@andy.fingerhut cheshire does have protocols to extend its implementation, but I don't see how I would differentiate one format from another without metada or somehow extending/subclassing the original class. Maybe my OO is a little rusty?

Using defn, there is no way to attach metadata on the fn itself rather than the var, is there?

hey everyone, Im seeking general advice regarding writing tests and fixtures lets say Im testing a REST API, specifically a GET /user/123 where 123 is the id of the test user create right before the test by a fixture

(defn create-delete-user [f]
  (fixture/create-user)
  (f)
  (fixture/delete-user))

(use-fixtures :each create-delete-user)

(deftest user-test
 (testing "get user bla bla .."
   here I need to compare the result of the HTTP call with the fixture user))

you could use a binding instead if you didn't want to use an atom:

(def ^:dynamic *user* nil)

(use-fixtures :each
  (fn [test]
    (with-bindings {#'*user* (fixture/create-user)}
      (test)
    (fixture/delete-user)))

which one is more idiomatic clojure? Im ok with anything, Im just asking because of shared mutable state etc

the idiomatic thing would be to use binding - my understanding was that with-bindings is a helper for macros

i always forget which func is which, for some reason my eyes gravitated towards with-bindings this time 😛

imo binding does feel more idiomatic. however, assuming test runs are independent, i typically prefer the "fixtures create/clear tables, while tests setup their data explicitly" route

I could also dont use a fixture to create data and do stuff inside a let block on the test itself, but it feels dirty

thats exactly what I am talking about, to be honest seems the most sane way of doing it

although it feels strange to mix setup code with the actual test, but maybe Im just used to something else and this is fine

some pedestal docs I stumbled across yesterday approached this with a purpose-built macro

(defmacro with-system
  [[bound-var binding-expr] & body]
  `(let [~bound-var (component/start ~binding-expr)]
     (try
       ~@body
       (finally
         (component/stop ~bound-var)))))

http://pedestal.io/guides/pedestal-with-component

you still end up with a let-like syntax in your test, but at least you don’t have to copy the setup/teardown

(use-fixtures :once
  (fn [test]
    (db/create-schema!)
    (test)
    ;; really only needed if your db instance is persistent
    (db/drop-schema!)))

(use-fixtures :each
  (fn [test]
    (db/clear-tables!)
    (test)))

(deftest test-something
  (let [user (db/crete-test-user!)]
    (sut/do-a-thing user)))

imo it all really depends on how much your tests share, how complex the db is, etc

thanks everyone for the input 🙂

Is it possible to get an ISO String formatted date in Clojure without using Java? ie is there a built in for clojure? (iso string):

"2017-06-09T06:59:40.829-00:00"

If I start a thing in the REPL that is supposed to read from STDIN, how do I send something to it?

by sending something to stdin - or more generally you can bind *in* to an apropriate source of input

clojure's read etc. will use whatever *in* is set to (it can be set dynamically using binding)

when you use a network repl client, *in* will be bound such that read still works (unless other tooling like your editor gets in the way)

of course, be wary of calling read in a background thread while accepting input on the same *in* in the main thread (and visa versa)

Interactivity would be nice, but it's okay if I have to bind *in* to something. Since there is only one Java process now (the REPL's) I was confused who will capture the input. Your answer helps! Thanks.

you don't have to bind *in* if you want to use the same input source as the repl itself, it will just work (unless an editor breaks that...)

Since the REPL is already running, is there a way to "attach" to the stdin now?

the *in* of your repl client is the one that will be used by read, not the one of the server process

how did you start the server? it might be possible to get its stdin, it might not, but it shouldn't matter

That still means I have to dump something in a text file and bind that to *in*. Is there another way?

if you want to read from a text file, that's pretty much how you do it - unless you want to use slurp and read-string instead of read

^ The server is just CIDER jack in.

that's why I mentioned editors

thanks to cider jack in, emacs owns your server's real stdin and I doubt you'll get it back

but you shouldn't need it - nothing in clojure relies on the identity of stdin itself, it all uses the *in* abstraction instead

Is there a secret way for aliases to include other aliases in deps ?

@adam678 No. Aliases cannot bundle together other aliases. It's quite a common request.

Might it be fairly straightforward to write a Clojure program that reads a deps.edn file, or something similar to one that introduces some new convention for data that lets one alias reference another one, and merge the contents of the aliases together? Seems like a potentially nifty 3rd-party utility, although definitely understandable if Clojure core team would not want to write/maintain such a thing.

That would open the door to N different tools (or perhaps one that combines N different features) for reading something, and generating a deps.edn file.

I usually add a few bash scripts for common tasks which all have the proper aliases.

heck, you can even add a bin/clj script that does pretty much what you’re saying

Just for info, is it by choice or by constraint? Otherwise yes, custom bash scripts is what I am doing, but it does feel too "smart". Maybe it is for the best...

just bash it – it’s for the best

(famous last words, but srsly tho)

I've just been duplicating for now

Also, while you can't have an alias of alias, you can list out multiple alias when running clj to combine them

clj -A:foo:bar

Oh yeah, by custom bash scripts this is what I meant, so that I don't have to type long chains of aliases combinaisons

Ya, you can just setup a bash alias for that command

I think that's fine

I even have some bash alias for single alias. Like I've remapped cljto clj -A:repl

I'd like to run clojurescript tests using https://github.com/lambdaisland/kaocha-cljs kaocha-cljs. So I put the [lambdaisland/kaocha-cljs "0.0-71"] dependency in my lein project.clj, and restart the repl and run the command in the root directory:

clojure -m kaocha.runner unit-cljs

Execution error (FileNotFoundException) at clojure.main/main (main.java:40).
Could not locate kaocha/runner__init.class, kaocha/runner.clj or kaocha/runner.cljc on classpath.

clojure doesn't use project.clj

you probably want the koacha lein plugin, assuming such a thing exists

why does kaocha-cljs exist then if you could just use kaocha for running cljs tests?

never mind, you are using koacha-cljs not koacha, and that doesn't use lein

it looks like you would need to migrate away from lein to use koacha-cljs, or port it to lein somehow

so I'm using the Luminus template, and I haven't yet needed to worry about the connection between cljs and clojure. But any cljs dependency I put in the project.clj dependencies and it just works.

sure, that's how the lein integration works

but koacha-cljs is built around clj/clojure which is a different tool, not compatible with lein

how to port kaocha-cljs to lein

?

lein run kaocha.runner unit-cljs should work

@souenzzo that gives me this error:

.BindException: Address already in use
	at .bind0(Native Method)
	at .bind(Net.java:433)
	at .bind(Net.java:425)
	at .ServerSocketChannelImpl.bind(ServerSocketChannelImpl.java:223)
	at io.netty.channel.socket.nio.NioServerSocketChannel.doBind(NioServerSocketChannel.java:128)
	at io.netty.channel.AbstractChannel$AbstractUnsafe.bind(AbstractChannel.java:558)
	at io.netty.channel.DefaultChannelPipeline$HeadContext.bind(DefaultChannelPipeline.java:1358)
	at io.netty.channel.AbstractChannelHandlerContext.invokeBind(AbstractChannelHandlerContext.java:501)
	at io.netty.channel.AbstractChannelHandlerContext.bind(AbstractChannelHandlerContext.java:486)
	at io.netty.channel.DefaultChannelPipeline.bind(DefaultChannelPipeline.java:1019)
	at io.netty.channel.AbstractChannel.bind(AbstractChannel.java:254)
	at io.netty.bootstrap.AbstractBootstrap$2.run(AbstractBootstrap.java:366)
	at io.netty.util.concurrent.AbstractEventExecutor.safeExecute(AbstractEventExecutor.java:163)
	at io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:404)
	at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:465)
	at io.netty.util.concurrent.SingleThreadEventExecutor$5.run(SingleThreadEventExecutor.java:884)
	at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)
	at java.lang.Thread.run(Thread.java:748)
Syntax error (BindException) compiling at (/private/var/folders/zz/zyxvpxvq6csfxvn_n0000000000000/T/form-init6496307984697349116.clj:1:125).
Address already in use

Full report at:
/var/folders/zz/zyxvpxvq6csfxvn_n0000000000000/T/clojure-9061200669573262320.edn

(require '[kaocha.runner])
nil
user> (kaocha.runner unit-cljs)
Syntax error (ClassNotFoundException) compiling at (*cider-repl luminus/vendo:localhost:63551(clj)*:62:7).

the lein command line would translate to (koacha.runner/-main "unit-cljs")

Still, I get 1. Unhandled java.lang.ClassNotFoundException koacha.runner URLClassLoader.java: 382 http://java.net.URLClassLoader/findClass DynamicClassLoader.java: 69 clojure.lang.DynamicClassLoader/findClass ClassLoader.java: 418 java.lang.ClassLoader/loadClass DynamicClassLoader.java: 77 clojure.lang.DynamicClassLoader/loadClass ClassLoader.java: 351 java.lang.ClassLoader/loadClass Class.java: -2 java.lang.Class/forName0 Class.java: 348 java.lang.Class/forName RT.java: 2211 clojure.lang.RT/classForName RT.java: 2224 clojure.lang.RT/classForNameNonLoading Compiler.java: 1041 clojure.lang.Compiler$HostExpr/maybeClass Compiler.java: 7045 clojure.lang.Compiler/macroexpand1 Compiler.java: 7075 clojure.lang.Compiler/macroexpand Compiler.java: 7161 clojure.lang.Compiler/eval Compiler.java: 7132 clojure.lang.Compiler/eval core.clj: 3214 clojure.core/eval core.clj: 3210 clojure.core/eval interruptible_eval.clj: 91 nrepl.middleware.interruptible-eval/evaluate/fn main.clj: 437 clojure.main/repl/read-eval-print/fn main.clj: 437 clojure.main/repl/read-eval-print main.clj: 458 clojure.main/repl/fn main.clj: 458 clojure.main/repl main.clj: 368 clojure.main/repl RestFn.java: 137 clojure.lang.RestFn/applyTo core.clj: 665 clojure.core/apply core.clj: 660 clojure.core/apply regrow.clj: 18 refactor-nrepl.ns.slam.hound.regrow/wrap-clojure-repl/fn RestFn.java: 1523 clojure.lang.RestFn/invoke interruptible_eval.clj: 84 nrepl.middleware.interruptible-eval/evaluate interruptible_eval.clj: 56 nrepl.middleware.interruptible-eval/evaluate interruptible_eval.clj: 155 nrepl.middleware.interruptible-eval/interruptible-eval/fn/fn AFn.java: 22 clojure.lang.AFn/run session.clj: 190 nrepl.middleware.session/session-exec/main-loop/fn session.clj: 189 nrepl.middleware.session/session-exec/main-loop AFn.java: 22 clojure.lang.AFn/run Thread.java: 748 java.lang.Thread/run

you still need to require koacha.runner , and it needs to be available as a dep you can require

that error is saying it hasn't been loaded

user> (require 'kaocha.runner) nil user> (koacha.runner/-main "unit-cljs") Execution error (ClassNotFoundException) at http://java.net.URLClassLoader/findClass (URLClassLoader.java:382). koacha.runner

And my project.clj dependency contains both Kaocha and kaocha-cljs

so why classnotfoundexception?