Re: [proposal] Type metatables per environment

[Patrick Donnelly <batrick@...>]

On Thu, Dec 22, 2011 at 12:18 AM, David Manura <dm.lua@math2.org> wrote:
> On Wed, Dec 21, 2011 at 10:30 PM, Daurnimator <quae@daurnimator.com> wrote:
>>> Patrick Rapin <toupie300@gmail.com> writes:
>>> > My proposal is the following: provided it is possible, why not limit
>>> > the metatable scope to the environment of the current function?
>>> > Even better, I could imagine that the type metatables could be placed
>>> > in the metatable of _ENV and manipulated from there.
>>> > Type metatables are nearly unusable in a library, since the library
>>> > author cannot assume that the custom metatable won't have side effects
>>> > or conflicts in other libraries or user scripts.
>>>
>>> Soooo what are the details?  How does the compiler implement this?
>>> How would it impact performance?
>
> I had similar ideas in [1] for the same reasons.  It does not
> necessarily require a change to the VM but could be implemented at
> compile time or as a preprocessor (including Metalua).  For example,

Problem with that is it would be completely non-viable for arithmetic
operations. It would make numeric arithmetic dead slow...

-- 
- Patrick Donnelly