Re: [libxml++] libxml++ future

[Dan Dennedy <dan dennedy org>]

On Thu, 2003-09-25 at 18:42, Christophe de Vienne wrote:
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> Hi all,
> 
> Here are a few features or little technical points I'd like to see in libxml++ 
> one day. Some could be included in the 1.0 version, while others will 
> certainly wait for a 1.2.
> 
> I would appreciate you to comment them : do you think it worth it having such 
> feature, and do you think it is a good technical choice.
> 
> I may have forgot some things important for you, don't hesitate to suggest 
> them.
> 
> - From you observations I will make a first RoadMap.
> 
> *******************************************************************************
> 1 - postfix private members intead of prefixing them with an underscore
> 
> target version : 1.0
> 
> The ISO c++ standart reserve names with a leading underscore to the 
> implemention. One shouldn't use some.
> Although there is no risk of real problem with that, I think it would be 
> cleaner.
> 
> *******************************************************************************
> 2 - wrap xmlIO.
> 
> target version : 1.0
> 
> xmlIO interface allow the creation of our own Input/Output Buffers. Wrap them 
> is an elegant and efficient way to reduce some useless potentialy big strings 
> copy.
> 
> Think about how to send a document to a stream. Currently we have to do :
> 
> std::ostream & output = std::cout; // could be any ostream of course
> std::string tmp = document.write_to_string();
> output << tmp;
> 
> In the above code, the entire document is written to a buffer by libxml, then 
> copied to a std::string by libxml++ which is finally returned by 
> write_to_string(). Even the a COW implementation of std::string, we'll need 
> twice more memory than the size of the document. With a non-COW 
> implementation it is even worse : it may be copied 3 or 4 time.
> 
> I wrote a small wrapper to xmlOutputBuffer and implemented a 
> Document::write_to_stream() function. The precedent code become :
> 
> std::ostream & output = std::cout; // std::cout is still an example of course
> document.write_to_stream(output);
> 
> The advantage is much more than just writing 1 line instead of 2. The entire 
> document is never in memory. libxml write to buffer by small pieces which are 
> immediatly sent to the stream by the wrapper. A patch demonstrating this is 
> on the patch manager if you want to experiment it. The wrapper allow the user 
> to very easily define it's own OutputBuffer. I modified dom_build example to 
> test it, and it works pretty well.
> 
> Another possible thing is to wrap xmlInputBuffer. Although we can (and did) 
> implement parse_stream without it, it would permit to implement 
> xmlTextReader.getRemainder() in an elegant way (cf. 3).
> 

I think this is good, but I am also very interested in SAX
serialization, perhaps based upon one of node iterators below. I think
you can count on that conribution coming from me.

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I am also personally interested in entity-support in the near term.