Re: [boost] RFC: Boost.XML API prototype in the sandbox

From: Stefan Seefeld (seefeld_at_[hidden])
Date: 2007-07-09 23:12:29

Phil Endecott wrote:

> As far as I can see, what you have is a wrapper around the GNOME 
> libxml2 (which has an MIT-license and is cross-platform) that 
> implements something that you call dom, but is not the standardised 
> "DOM" API for XML (http://www.w3.org/DOM/).

Right. The "DOM" API isn't actually standardized for anything but Java.
So in my attempt to provide a "DOM-like" API I have been trying to capture
the semantics, not the syntax, and map that to "modern C++ style" idioms.

To me, DOM stands for an API that allows in-memory manipulation of, well,
structured documents. That includes full (generic) tree traversal, as well
as XML-specific operations, such as XPath-based node lookup, validation,
as well as other domain-specific operations.

Finally, it is important to keep a balance between encapsulation and
transparency. While it is true that, semantically at least, one could
map some of the helpers by STL (or boost, for that matter) types, I
deliberately refrained from such an approach, to allow existing implementations
to be bound to the API. In particular, I'm using here libxml2 as backend,
which has been fine-tuned for best performance over a couple of years.
I'm not courageous / naive enough to attempt to match such an implementation
with a new one. Instead, I want a seamless mapping that doesn't impose any
unnecessary copying or other indirection to mitigate the 'impedance mismatch'.

I will try to write my thoughts and design rationales up in a document, so
things become a little clearer.

Thanks for your comments !

                Stefan

-- 
      ...ich hab' noch einen Koffer in Berlin...