[development] Installation -- Can A Module "Refuse" To Be Installed?

[Rob Thorne]

I've started to write .install files for the modules I'm responsible 
for.  Mostly this is pretty straightforward.  But there are a few areas 
I'm hoping there is support for in the system:

    * UI for problems/status during install:  I've made it a practice to
      do like merlinofchaos and put up a message to indicate I've
      installed tables (with a call to drupal_set_message).  It's less
      clear what's best to call if there's a problem.
    * I've noticed that there are calls in install.inc to register
      schema versions, but I haven't seen any examples of their being
      used.  How *should* those functions be used?
    * Dependencies are an issue for some of the stuff I'm installing. 
      It would be a good thing if the .install could detect that a
      needed module was not present, and in that case, put up an error
      message and refuse to install.  Is there a mechanism to do this
      currently?

Thanks,
Rob

Rob Thorne
Torenware Networks