Easiest way to manage my CLASSPATH?

Question

I'm beginning to play with Clojure a bit and my Java experience is pretty limited. I'm coming from the dynamic world of Ruby and OO, so the functional side of things is very interesting!

Anyway, as I discover libraries and various tools for use (and the tutorial files for the Pragmatic Clojure Book), everything typically calls for placing files in the CLASSPATH in order for Clojure to see the library for use.

Is there such thing as good CLASSPATH practice? Would I ever want to only have a CLASSPATH with just the external libraries of files I need or can I go ahead toss any library or file I would ever need in a directory and simply define it as my CLASSPATH and only require what's needed?

If it helps, I'm an OSX and Emacs user (Using slime and swank-clojure).

Answer 1

I recommend using leiningen and lein-swank to manage this. You can start a REPL in the directory and connect to it from Emacs.

Answer 2

Personally, I'm using a variant of a clojure-project elisp function by Phil Hagelberg, see source in this post to the Clojure group. It sets up the classpath appropriately for the project you'll be working on, then launches SLIME. (EDIT: You'll need to change the value which gets assigned to swank-clojure-jar-path to point to clojure.jar. I'm using (expand-file-name "~/.clojure/clojure.jar") as the default.)

To answer the question about having everything on the classpath all the time vs only throwing in what's needed: to the best of my knowledge, nothing will actually break if you take the first approach (I know I do that for experimental purposes), but apparently things might break with the first approach (see cjstehno's comment below) and in a proper project I find the second to be cleaner. At some point it'll be necessary to determine what libs are being used (and which versions of them), if only to tell leiningen (or maven) about it -- why not keep tabs on it as you go.

Answer 3

We are using Clojure and use a number of infrastructure tools, especially Eclipse (IDE) (http://en.wikipedia.org/wiki/Eclipse_%28software%29) and maven (http://en.wikipedia.org/wiki/Apache_Maven). maven manages libraries and jar dependencies so if you have a number of these and they are likely to grow start using maven.

In answer to your original question you can just put your jars in one directory and you can access them by name every time you run. But you will benefit from the tools...

If you are just exploring then Eclipse will probably manage your jar files fairly painlessly. You can add these to the project as required through the Build Path -> Configure Build Path option.

As your work progresses you will possibly wish to split it into Projects which Eclipse supports so you can add your (or other projects) to your Build Path.

If you use external Clojure libraries look to see if they have been packaged as maven projects (they will have a pom.xml file). The POM will give a list of dependencies. #