From: pjb@... (Pascal J. Bourguignon)
Date: 2009-01-29T09:32:39+09:00
Subject: Re: Bitwise question

Rob Biedenharn <Rob@AgileConsultingLLC.com> writes:

> On Jan 28, 2009, at 4:32 PM, Pascal J. Bourguignon wrote:
>
>> Andrew Barringer <abarringer@bsecure.com> writes:
>>
>>> What's the best way to find out if user has access to all requested
>>> permissions?
>>
>> (def check(permissions,bits)
>>  (bits . inject(true) { | r , b |
>>                    (r and (0 != (permissions & (1 << b))))
>>                 })
>> end)
>>                                                                                              nil
> Or a simpler version:
>
> class Integer
>    def as_bits
>      ary = []
>      (self.size*8).times {|i| ary.unshift(i) if self[i].nonzero?}
>      ary
>    end
>
>    def check_permissions(*bits)
>      bits.all? {|bit| self[bit].nonzero? }
>    end
> end

Simplier?  A class, two methods, a lot of operations, a lot of memory!

-- 
__Pascal Bourguignon__