Custom messages

[Dirk Laurie <dpl@...>]

On Wed, Feb 16, 2011 at 01:24:57PM +0200, Julien Duminil wrote:
> 
> Maybe we could add an error/custom message to every nil variable.
> Plus, add of a function reason(nil_var) that give the message.
> 

This idea is much more generally applicable.

One non-invasive implementation could be a library function:

debug.setmessage(t)

If you never call this routine, you've got standard Lua.  Otherwise,
you can use it to deprecate features to your heart's content.

debug.setmessage{condition='assign_nil',severity='error'}
debug.setmessage{condition='implicit_conversion',severity='warn'}

It could also be used to make Lua talk non-English.

Dirk