Re: [boost] [xint] Question about suitability, portability, and "Boostiness"

Subject: Re: [boost] [xint] Question about suitability, portability, and "Boostiness"
From: Chad Nelson (chad.thecomfychair_at_[hidden])
Date: 2010-04-13 01:55:18

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On 04/13/2010 01:34 AM, Scott McMurray wrote:

> You said the "quick digits" are inside the struct to which the xint
> object holds a pointer, so using them requires dynamic allocation.
> 
> I picture it something like this:
> 
>     struct xint {
>         union {
>             internal_xint *ptr;
>             intptr_t small;
>         };
>         xint() : small(1) {}
>     };
> 
> Then you only allocate internal_xints on even addresses, so that if
> (small&1), then the value of the xint is ashr(small, 1).
> 
> And that way I don't have to worry that a use of a common literal,
> like xint(3), might throw an exception,

And in exchange, every function in the library that uses the internals
of the integer -- and there are several -- would need to have
special-case handling for small numbers. Not worth the trade-off.
- -- 
Chad Nelson
Oak Circle Software, Inc.
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