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2014-03-23 23:32 GMT+02:00  <>:

> On Sun, Mar 23, 2014 at 04:40:24PM -0300, Roberto Ierusalimschy wrote:
>> > I'd like to suggest that the timing for changes to coercion is in this
>> I am afraid elimination of this conversion is a much deeper disruption
>> than it seems; I would love to be proved wrong.
> Most common breakage seem to be (%d+) captures. This is reasonably
> possible to work around for legacy code by wrapping string.* to
> catch (%d+) in patterns and call tonumber() for given result position.

Breakages that would give an error message are relatively easy
to handle.

For my applications, the following halfway stage would be sufficient:
when _both_ operands in an arithmetic expression (including, now,
bitwise operations) are strings, check for the presence of the
appropriate metamethod _before_ trying coercion and performing
the operation on numbers.


$ lua53
Lua 5.3.0 (work2)  Copyright (C) 1994-2014, PUC-Rio
> 1+2 -- so that you can see the difference later
> "1"+"2"   -- coercion goes to float!
> getmetatable"".__add = function(x,y) return x..'+'..y end
> "a"+"b"
> "1"+2  -- for this case, I can live with coercion
> "1"+"2"   -- but here I want the result "1+2"

Would this still be very disruptive?