Smarter Erlang Programming with Emakefile Options and user_default

Say you’ve got an Erlang app with the standard file system layout, with your source code in src/ and your compiled code in ebin/. I’ve found this makes using the interactive shell interpreter a little harder.

Lets use the Emakefile that Erlang supports to let us recompile and reload our code on the fly.

Create a file called Emakefile, and put the below line in it. There’s other options, but this keeps things simple.

{"src/*", [report, verbose, {i, "include"}, {outdir, "ebin"}] }.

Now you can recompile & load everything like this:

1> make:all([load]).

But as far as I can tell, it won’t see your ebin directory. Keep reading.

Lets kick it up a notch. Typing make:all([load]) is obnoxious - lets use the power of user_default as written below.

http://medevyoujane.com/blog/2010/1/3/erlang-quick-tip-the-user_default-module.html

I wasn’t able to get the user_default module to work unless I specifically loaded it as follows:

code:load_abs("/Users/jhaddad/ebin/user_default").

(Found on http://amiest-devblog.blogspot.com/2008/01/reloading-all-code-from-erlang-shell_16.html)

Here’s all I have in there - I really just needed r() to work to reload everything.

-module(user_default).
-compile(export_all).
r( ) ->
    make:all( [load] ).

I’ve been told there’s a reloader script in mochiweb that will auto load everything for you - that’ll be the subject of a later blog post. (edit: finally wrote the autoloader how to)

References

• Make module documentation: http://www.erlang.org/doc/man/make.html

• Compile options: http://www.erlang.org/doc/man/compile.html