Graciously handle empty paths to by-path

[arichiardi]

Hi folks!

When the paths param to by-path is an empty seq, this is the 💥 I receive :

                              java.lang.Thread.run              Thread.java:  745
java.util.concurrent.ThreadPoolExecutor$Worker.run  ThreadPoolExecutor.java:  617
 java.util.concurrent.ThreadPoolExecutor.runWorker  ThreadPoolExecutor.java: 1142
               java.util.concurrent.FutureTask.run          FutureTask.java:  266
                             clojure.lang.AFn.call                 AFn.java:   18
               clojure.core/binding-conveyor-fn/fn                 core.clj: 2020
                                 boot.core/boot/fn                 core.clj: 1029
                               boot.core/run-tasks                 core.clj: 1019
              pandeiro.boot-http/eval1138/fn/fn/fn            boot_http.clj:  110
                    boot.task.built-in/fn/fn/fn/fn             built_in.clj:  416
                 boot.task.built-in/fn/fn/fn/fn/fn             built_in.clj:  419
              boot.task.built-in/fn/fn/fn/fn/fn/fn             built_in.clj:  419
                    boot.task.built-in/fn/fn/fn/fn             built_in.clj:  235
               adzerk.boot-reload/eval803/fn/fn/fn          boot_reload.clj:  187
            adzerk.boot-reload/eval803/fn/fn/fn/fn          boot_reload.clj:  188
                        adzerk.boot-reload/changed          boot_reload.clj:   29
                             boot.core/not-by-path                 core.clj: 1266
                        clojure.lang.RestFn.invoke              RestFn.java:  442
                                 boot.core/by-path                 core.clj: 1261
                        clojure.lang.RestFn.invoke              RestFn.java:  442
                          boot.core/file-filter/fn                 core.clj: 1221
                                clojure.core/apply                 core.clj:  657
                       clojure.lang.RestFn.applyTo              RestFn.java:  132
                    clojure.lang.AFn.applyToHelper                 AFn.java:  152
                        clojure.lang.RestFn.invoke              RestFn.java:  399
                       clojure.lang.AFn.throwArity                 AFn.java:  429

Potentially this involves also the other by-* and not-by-* functions. It basically happens because juxt does not like to be called in an "empty" apply this.

Should be an easy fix in file-filter 🕺

[hit023]

A possible try-catch like this:

[hit023]

Any feedback/ constructive-criticism would be great!

[arichiardi]

I don't see your try catch but it is probably better to avoid passing nil on there instead of let it throw and then catch the exception. I would not call apply juxt .. at all and return nil directly there.

[DonyorM]

So @hit023 have you added a fix for this that you're planning to pull request, or should I see if I can give it a shot?

[hit023]

@DonyorM , you can go ahead with it.

[martinklepsch]

Fixed in cb923ee