Re: What's up with token filters (Re: New operators?)

[roberto@... (Roberto Ierusalimschy)]

> I can see the problems arising from a module that relies on some  
> token-modded behaviour, but such modules should just not be made. I  
> think this isn't a problem in the generic sense; people would use  
> token filters for small syntax "enhancements" easying the application  
> level work they do, knowing which ones they load in _their_  
> environment. Modules and redistributable code should use plain Lua only.

This seems whishful thinking. Once macros or token filters are available,
people will use it for all sorts of things. Moreover, as far as I remember
one of the main users of token filters would be end users, as filters
allow us to make the language more domain specific. Also keep in mind
that token filters are not easy to write (quite the opposite), so there
will be great pressure for reuse of them.

We already have this experience, with Lua 2.1. When we introduced
fallbacks, we thought exactly in this line (limited and "local" use).
We spent the next years trying to solve the problems.

-- Roberto