From: Ian Roddis <ian.roddis@...>
Date: 2006-10-24T22:49:24+09:00
Subject: Bitwise inversion of Bignum

A bitwise inversion of a Bignum sometimes yields odd results. As tested 
in 1.8.5:

./ruby -v

ruby 1.8.5 (2006-08-25) [i686-linux]
./ruby -e 'a= "7fffff00".hex ; b= "ffffff00".hex ; printf "%b => %b\n", 
a, ~a ;

printf "%b => %b\n", b, ~b'
1111111111111111111111100000000 => ..10000000000000000000000011111111
11111111111111111111111100000000 => ..1

In the first case, the '..1' is expected, as per the documentation, but 
annoying. Generally when I need to invert a number, I expect a result of 
the same length as the original. Since ruby number classes are 
inherently variable length I could not rely on the non-significant bits 
even if I wanted to. Is it possible to put in a vote for a Bignum ~ 
operation to return a value of the same length as the largest argument?

The second case is just bizzare. Is this a bug?

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