Saturday 7 February 2004

On XML 1.1

Dare blogs about XML 1.1.

Reading the summary Dare links to reminds me of C99: a solution looking for a problem.

There isn't anything majorly wrong with XML 1.0, and the things that are wrong with it aren't fixed in 1.1 anyway.

I don't mind standardisation committees working on producing standard versions of what had been slightly-incompatible variants of a technology. However, a standards committee deciding on extensions to an existing standard have a real tendency to either go over the top (C99) or tinker with things that don't need fixing (XML 1.1). I hope C++ 0x doesn't turn into a nightmare, but the signs at present are that the library will get a lot of extensions, the language will get a few minor ones, and (as long as you haven't used any new keywords) your C++98 programs will upgrade directly.

Indeed a standards committee can end up operating in a rareified academic atmosphere, inventing something that's only of very vague relevance to commercial software development.

Of course the C++ standardisation committee itself ended up inventing things like export, which actually turns out to be fairly useless. It might slightly reduce the time taken to compile a large C++ program with a lot of templates, but Visual C++'s precompiled headers (apparently something similar is also supported by GCC) already exist and are likely to be more beneficial. The goal of shipping a binary version of a template is scuppered by the fact that C++ allows so much variation between instantiations of a template - it can't simply be implemented by 'dope lists' as Ada generics can. The CLR gets away with it by instantiating at runtime, but this works against the general philosophy of C++.

About the only instance of standards upgrade done right I can think of is Ada 95, but even that broke a number of Ada 83 programs, and introduced a very strange object-based syntax for allegedly object-oriented programming.

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