Re: tonumber(), toboolean()???

[Lisa Parratt <lisa@...>]

Chris Marrin wrote:
> Lua has a very nice tostring() function, which can use a "__tostring" 
> metamethod to give string conversion support to any user defined type. 
> And tonumber() exists in 5.1, but its implementation does not include a 
> "__tonumber" metamethod call. It simply converts a number or string to a 
> number. Everything else returns nil. So, the first question is, why not 
> make the implementation of tonumber() parallel to that of tostring()?
>
> And the related question is, why not have a toboolean() as well, with 
> the same sort of __toboolean metamethod?

I've implemented these - they're a little hairy. They also require 
extensive changes to the statements and standard libraries so they don't 
cause errors during type checking.

--
Lisa