Node Process Spawn help

[Nick Featch]

Hi we have a Clojurescript exec process working

(def child-process (nd/require "child_process"))

(defn exec [cmd opt fn] (.exec child-process cmd opt fn))

(let [opt (clojuremap->jsobj {:cwd "path"})]
(exec "ls -la" opt (fn [err stdout stderr] ....)))

But can't figure out how to swap exec for spawn. Has any one done this?

[Joaquín Oltra]

Take a good look at the node.js docs, and show how you are swapping exec for spawn. They are different functions and they take different arguments. One difference for example is that the second argument in spawn is an array with the args and in exec is options for the execution.

http://nodejs.org/api/child_process.html#child_process_child_process_spawn_command_args_options

Another big difference is that exec gives you the results in the callback and spawn returns a ChildProcess object which is an event emitter, so it is not a matter of just swapping which function you are using.

Look at the examples in the docs and translate them to cljs, it should be easy and there are plenty of them.

Cheers

[Nick Featch]

Hi thanks for your reply. Sorry my post did suggest I was simply just swapping .exec for .spawn and hopping it would work ha ha. I've studied the docs and tried to apply the differences as you can see below.

(def child-process (nd/require "child_process"))

(defn spawn [cmd arg opt] (.spawn child-process cmd arg opt))

(let [opt (utl/cmap->jobj {:cwd project-path})
proc (env/spawn "silk" (array "reload") opt)]
(.on (.-stdout proc) 'data' (fn [data]
(.log js/console data))))

The process runs (I can see it creating the file and directories I expect) but no logging is preformed. Can you pass a clojurescript anonymous function to a JavaScipt method?

[Joaquín Oltra Hernández]

Yes, they are the same and can be used interchangeably.

I've tried it and it works without any problem.

ClojureScript:cljs.user> (def spawn (.-spawn (js/require "child_process")))
#<function (file /*, args, options*/) {
...
ClojureScript:cljs.user> (let [p (spawn "ls" #js["-l"])]
                           (.on (.-stdout p) "data" println))
#<[object Object]>
#<total 1064
-rw-r--r--  1 jkn  staff    1817 Feb  5 13:27 README.md
drwxr-xr-x  3 jkn  staff     102 Feb  6 10:53 checkouts
-rw-r--r--  1 jkn  staff  536522 Feb  5 13:27 cljs_node_lighttable.js
-rw-r--r--  1 jkn  staff     830 Feb  5 13:27 project.clj
drwxr-xr-x  3 jkn  staff     102 Feb  5 13:27 src
drwxr-xr-x  4 jkn  staff     136 Feb 10 15:04 target
>

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[Nick Featch]

Oh wow you've solved it, thank you. The way I'd imported is flawed, your way works.

[Joaquín Oltra Hernández]

Glad I could help :)