Walter's DConf 2014 Talks - Topics in Finance

[Paulo Pinto]

Am 23.03.2014 18:38, schrieb Sean Kelly:
> On Saturday, 22 March 2014 at 14:04:01 UTC, Daniel Davidson wrote:
>>
>> For example, I could see technical reasons why in certain non-quant
>> areas like XML parsing where D can be faster than C++.
>> (http://dotnot.org/blog/archives/2008/03/12/why-is-dtango-so-fast-at-parsing-xml/)
>> But then, with a large amount of time and unlimited funding the
>> techniques could probably be duplicated in C++.
>
> Try no funding and a trivial amount of time.  The JSON parser I wrote
> for work in C performs zero allocations and unescaping is performed on
> demand.  D arguably makes this easier by building slicing into the
> language, but not decoding or copying is a design decision, not a
> language artifact (at least in the case of C/C++ where aliasing data is
> allowed).  The take-away from that Tango article is that the performance
> hit for parsing is aggressively decoding data the user may not care
> about or may not want decoded in the first place.  This just happens to
> be the approach that basically every XML parser on the planet uses for
> some ridiculous reason.

At least on Java world it is not quite true.

If you use XML parsers that return a DOM or SAX, yes quite true.

But as far as I can tell, XML streaming parsers (StAX) only parse on demand.

Unless I am missing something.

--
Paulo