Re: [boost] [optional] generates unnessesary code for trivial types

Subject: Re: [boost] [optional] generates unnessesary code for trivial types
From: paul Fultz (pfultz2_at_[hidden])
Date: 2012-02-09 15:58:48

----- Original Message -----

> From: Domagoj Saric <dsaritz_at_[hidden]>
> To: boost_at_[hidden]
> Cc: 
> Sent: Thursday, February 9, 2012 2:09 PM
> Subject: Re: [boost] [optional] generates unnessesary code for trivial types
> 
>& quot;paul Fultz"  je napisao u poruci interesnoj 
> grupi:1328802527.4759.YahooMailNeo_at_web112602.mail.gq1.yahoo.com...
>>  Actually, you could just take the optional_traits as the first parameter. 
> So you define
>>  optional<T> or optional<optional_traits<my_traits<T> > 
>> . Then optional would be
>>  specialized for optional_traits that will get the user-defined traits.
> 
> (possibly a bit of work to still get the special trivial destructor and 
> assignment functionality in the specialization, but) Clever ;)


Actually, you could use an optional_impl class, that always uses traits. And then
when the user is not passing in their own traits you would pass in default_traits.
Something like this:

template<class T>
class optional : public optional_impl<default_traits<T> >
{
//Foward constructors, and operators
};

template<class Trait>
class optional<optional_traits<Trait> : public optional_impl<Trait >
{
//Foward constructors, and operators
};

Then the assign operator would forward to an assign method in the base class.
Of course, this would mean that if T is trivially assignable, optional<T> would not
be trivially assignable. Was that one of your goals of the original design?