Re: [boost] Serialization library review

From: Matthias Troyer (troyer_at_[hidden])
Date: 2002-11-26 02:23:18

On Tuesday, November 26, 2002, at 03:01 AM, Robert Ramey wrote:

> Date: Mon, 25 Nov 2002 10:41:17 +0100
> From: Matthias Troyer <troyer_at_[hidden]>
>
>>> I guess this should be changed to:
>>> 	#ifdef BOOST_HAS_MS_INT64
>>> 	virtual basic_iarchive & operator>>(int64_t & _Val) = 0;
>>> 	virtual basic_iarchive & operator>>(uint64_t & _Val) = 0;
>>> 	#endif
>>> 	#ifdef BOOST_HAS_LONG_LONG
>>> 	virtual basic_iarchive & operator>>(long long & _Val) = 0;
>>> 	#endif
>
>> This sounds better. Thanks.
>
> whoops, that doesn't work either - this will take some work to address.
>
>
>>> why can't this be handled using
>>>
>>> 	basic_oarchive::write_binary(void *p, size_t count)
>
>> This does not allow type-specific transformation (e.g. change of byte
>> order) to be performed. Thus we neeed one such function for each
>> primitive type.
>
> I fail to see the problem.  If you want superfast i/o with only once
> virtual function call use
>
> basic_oarchive::write_binary(void *p, size_t count)
>
> If you want each array item handled individually use
>
> ar << t
>
> Note that if t is a fundamental type, all serialization machinery
> is effectively bypassed.  So the only overhead is one vtable
> indirection which should be small compared to doing something
> like changing bigendian to little endien

No, Robert, one virtual function call can be much slower than changing 
byte order when copying integers.

Matthias