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- Subject: Re: Numeric key collision related bug in Lua 5.3
- From: Tim Hill <drtimhill@...>
- Date: Wed, 22 Apr 2015 12:12:18 -0700
> On Apr 22, 2015, at 9:13 AM, Roberto Ierusalimschy <email@example.com> wrote:
> My guess is that the best sollution would be to change the definition
> of equality (to a simpler one :-). Two numbers should be considered
> equal if they represent the same mathematic value; period. (In terms
> of implementation, it means that integer-float should be compared
> converting the float to an integer; if the conversion fails, the numbers
> cannot be equal.) That definition is simple, sounds sensible and
> easy to explain, and makes equality transitive.
> -- Roberto
+1, for all the reasons you state.
What about relational operators? Consider this:
a = (1<<60) + 180
b = (1<<60) + 200
bf = b + 0.0
print(a < b) -> true
print(a < bf) -> false (!)
printf(a < math.tointeger(bf)) -> true
Of course, I carefully chose those numbers, but the truncating effect of integer->float will give strange results when doing (say) table.sort() on mixes of floats and integers.