Question

I have a clojure program that at some point executes a function called db-rebuild-files-table.
This function takes a directory filename as a single string argument and calls a recursive function that descends into the directory file tree, extracts certain data from the files there and logs each file in a mysql database. The end result of this command is a “files” table populated by all files in the tree under the given directory.

What I need is to be able to run this command periodically from the shell.

So, I added the :gen-class directive in the file containing my -main function that actually calls (db-rebuild-files-table *dirname*). I run lein uberjar and generate a jar which I can then execute with:

java -jar my-project-SNAPSHOT-1.0.0-standalone.jar namespace.containing.main

Sure enough, the function runs, but in the database there only exists a single entry, for the directory *dirname*. When I execute the exact same sexp in the clojure REPL I get the right behaviour: all the file tree under *dirname* get processed.

What am I doing wrong? Why does the call (db-rebuild-files-table *dirname*) behave inconsistently when called from the REPL and when executed from the command line?

[EDIT] Whats even weirder is that I get no error anywhere. All function calls seem to work as they should. I can even run the -main function in the REPL and it updates the table correctly.

Answer 1

If this works in the REPL, but not when executed stand-alone, then I would guess that you may be bitten by the laziness of Clojure.

Does your code perhaps need a doseq in order to get the benefits of a side-effect (e.g. writing to your database)?