Also, this should have no influence whatsoever on ShellJS when used normally, but would only help make plugins a bit easier 😄

I'm not really sure I understand how this helps... Could you explain it?

Other than that, LGTM.

@ariporad A plugin would require('src/common') (or whatever file we eventually move the plugin utils into) in order to register its own commands (using common.register()).

If the plugin is included before the ShellJS instance is created (require('shelljs-plugin-open') precedes require('shelljs')), then src/common.js is require()ed before shell.js. This is where the problems arise. src/common.js includes shell.js, so if shell.js hasn't yet been require()ed, Node goes and loads in shell.js. This tries to load src/common.js, but since we were in the middle of loading src/common.js, this returns common = {} (the empty object). Then, when shell.js loads in the built-in commands, it tries to common.register() them, but fails. This is because common is still {}, and doesn't have the .register attribute yet (and it won't until the initial require() completes). In essence, common.register() is used before it gets defined.

The problem didn't arise for normal ShellJS use because shell.js is require()ed first, so it is able to load in src/common.js completely before continuing to load each command (so common.register() is defined before it is used).

The solution here is to check if common.register() is defined as soon as shell.js is loaded for the first time. If common.register is not yet defined, invalidating the require-cache will force Node to load all of src/common.js (making sure that common.register() gets defined before it's used).

Hopefully that's a good explanation. I had to draw out dependency graphs to discover what the problem was and how to solve it. From what I've seen, however, it seems to work. I'll update the plugin after this is merged as a proof of concept.

Ahh... That makes sense. Thanks!

Yeah, it's a bit non-intuitive, but hopefully that was a clear enough explanation for all looking into the matter in the future.