Re: [boost] compact_optional -- prompting interest

Subject: Re: [boost] compact_optional -- prompting interest
From: Vladimir Batov (Vladimir.Batov_at_[hidden])
Date: 2015-09-28 22:04:04

On 09/28/2015 08:45 PM, Gonzalo BG wrote:
> Vladimir Batov wrote:
> > ... if I cannot provide "int", I should not be saying that I do.
>
> Using the library the best thing that I can say is that I'm providing a
> "compact_optional<int, some_policy, struct this_is_my_temperature_type_tag>
> ".

Indeed. Now I realize  that "compact_optional<>" introduces a new 
distinct type. So, my initial concern was unfounded.

More so, your example of vector<optional<int>> (with ~O(10^10) elements) 
seems to be a convincing use-case for such a type.

> Vladimir Batov wrote:
> > I do have the need to be real frugal when I store data to the disk. But for that purpose I have to be far more economical and size-specific than compact_optional.
>
> I use compact_optional to store data on disk and since
> sizeof(compact_optional<T>) == sizeof(T) I haven't ran into issues yet. How
> can one be more economical than that?

I had different economy in mind as I am forced to squeeze something 
represented, say, as "int" in memory into int16_t or int8_t and the 
likes to be stored on disk.