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- Subject: Re: tonumber(), toboolean()???
- From: Lisa Parratt <lisa@...>
- Date: Tue, 21 Feb 2006 15:02:24 +0000
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.