In message "[ruby-talk:01398] Bignum aset"
    on 00/02/15, Andrew Hunt <Andy / Toolshed.Com> writes:

>In class Bignum, there is a very handy method for bit reference ([]).
>But there is no corresponding bit setter ([]=).
>
>Is this deliberate?  I need an abritrarily large pile of bits to set and
>test, and this seems like the right place to do it.  Should I be using
>some different class instead?

Yes, I heard it is deliberate.  An instance of Numeric is a unique
object corresponding to a numeric. And, []= is usually a destructive
method.

Now, for example, imagine what happens by `2[0] = 1'.  Will 2 be 3?

So, we can see that this comes from same reason of the lack of ++
operator.

Regards,

-- gotoken