Re: [Boost-users] Editable XML Serialization

Subject: Re: [Boost-users] Editable XML Serialization
From: Robert Ramey (ramey_at_[hidden])
Date: 2010-09-15 19:56:45

Anne van Rossum wrote:
> Robert Ramey <ramey <at> rrsd.com> writes:

>> xml_in >> my data structure for some arbitrarily defined structure.
>> Of course after you become familiar with the library, it's easy to
>> see that this is not possible.  It's annoying to me how often this
>> is stated as a failing of the library.
>
> What I want "at the C++ side" so to say, is just the same as with
> boost::serialization. That supports already "custom" data structures,
> because in the serialize(Archive & ar,...) routine it is possible to
> define what fields to write/read. I am not talking about marshalling
> / unmarshalling to entire objects. Serializing arbitrary data
> structures does not make sense to me.

What I'm referring to is the the word xml_archive almost always
conjures up in many persons imagination something which would
take an arbitrary xml file and permit processng of it.  Serialization
can't do this even in concept since it maps the xml to the underly
C++ data structures.  This becomes obvious once you use it. But
often people take it up thinking that it's something that it isn't.

> However, I am not familiar with the library, so perhaps I
> misunderstood you. Forgive me, I just encountered it today.

lol - well it seems that you've actually used it - which makes
you a lot more familiar to you than it is to a many of those who
offer criticism.

>> b) It is possble to so some limited editing of xml (or other
>> archives) but this would be an ad hoc procedure subject to
>> errors.  you might change a value here and there but the minute
>> you change something tracked or add a value to a collection
>> or whatever, you're not going to be able to keep things consistent.
>> I guess you're familiar with this.
>
> Yes.

...

>> The usage would be the following:
>>
>> edit_archive<mfc_widgets> ea
>> ...
>> ea << my_data
>
> That's a solution. I would then need to distribute a separate binary
> to manipulate the XML files.

yes - but that binary would be generated "for free" without
having to code anything.

>My idea was to "misuse"
> boost::serialization for writing XML configuration files without the
> need to manually build DOM-like structures.

Indeed - any many have traveled this path.  And, as I understand it
some success in specific cases.  This has been done by tweaking
the xml_archive class or deriving from the current one.  So for
those cases it's an option.  Of course, personally I'm more interested in a
more general solution.

>For just changing
> configuration parameters, a graphical solution might be a bit
> cumbersome. It's a nice idea nevertheless!

actually this would be a series of classes

edit_archive<qtwidgets>,
...
edit_archive<textwidgets> // no GUI necessary ! - just a text editor

This last would likely be something generated with qi/karma which
is a whole 'nother playpen.

For simple configuratoin files, there are other options as well.
boost property tree comes to mind. Also one might make archive
which traps problematic cases like pointers so it would be usable
to make only "simple editable" xml.  etc,

Robert Ramey