Re: [Boost-users] [serialization] Creating new archives derivedfrom polymorphic archive

From: Robert Ramey (ramey_at_[hidden])
Date: 2006-03-11 00:14:31

The standard init function is called from the constructors.  I don't think 
you
want to replace this - but you could suppress it with the no_header
option when the archive is open.

On your derived archives, just add header and footer into the constructor
and desctructor.

Robert Ramey

Robert S. Grimes wrote:
> Oh, one last question - for now...
>
> As I said in my original posting, I essentially want a custom
> "header" and a "footer" to add to my archives.  What I'm looking for
> is the best way to hook into the archive creation process just before
> anything is written, and just after.  I want to support several
> different types of archives (e.g. text, binary, XML) with various
> types of signatures at the end (e.g. CRC, digital signature, etc.).
> My concept is to write a standard header that identifies what was
> written, then use a factory function that reads the header and
> returns the appropriate archive when reading.
>
> It seems there are some init functions that are for headers, but I've
> not yet figured out if that is the best spot, nor where the "footers"
> hook in. I'm poking about and may well find them, but I thought
> other, more expert, people might help me with the optimal approach.
>
> Thanks again!
> -Bob
>
>> -----Original Message-----
>> From: boost-users-bounces_at_[hidden]
>> [mailto:boost-users-bounces_at_[hidden]]On Behalf Of Robert Ramey
>> Sent: Friday, March 10, 2006 11:04 AM
>> To: boost-users_at_[hidden]
>> Subject: Re: [Boost-users] [serialization] Creating new archives
>> derivedfrompolymorphic archive
>>
>>
>> To do something like this, you'll have to invest some effort to
>> understand the serialization library at more depth that is required
>> for someone who just want's to use it.  I can't offer any "cookbook"
>> like approach.
>>
>> But I can help maybe a tiny bit.
>>
>> Note that the polymorphic versions of the archives classes are the
>> result of application of a "polymorphic archive adaptor" to any
>> other archive. This "polymorphic archive adaptor"  is little more
>> than a glorified typedef which uses the base archive type as a
>> parameter.
>>
>> So, you want to do this in two stages:
>>
>> a) make your own archive - from scratch or by derivation from
>> an existing one - be sure to test it.
>>
>> b) apply the "polymorphic archive adaptor"  to make a polymorphic
>> version.
>>
>> If you want to practice, you should be able to take the
>> demo_fast_archive example - which makes a derivation from
>> binary_?archive, apply
>> the "polymorphic archive adaptor"  and generate a
>> polymorphic_fast_binary_archive (or what ever).  This should take
>> about an hour to do.
>>
>> Good Luck
>>
>> Robert Ramey
>>
>>
>> Robert S. Grimes wrote:
>>> Hi,
>>>
>>> How do I get started?  I want to create a set of custom archives
>>> that include such features as a small header, CRC, digital
>>> signatures, etc.  I want to put this into a DLL, so I want to go
>>> the polymorphic route.  There are directions for creating new
>>> archives from the template versions, but not for the polymorphic
>>> versions.  I'm not sure the starting point is the same, so I
>>> thought I'd ask first, as this is stretching my abilities a bit.
>>>
>>> Thanks,
>>> -Bob
>>
>>
>>
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