Zack asked for website meta languages

for redoing his homepage.

Well, I redid my homepage last february, using XML and XSLT. A monster XSLT stylesheet, because I wanted to keep my template outside of the stylesheet.

I can not recommend XSLT. Using it for templating is quite messy. XSLT is okay if you want to transform one representation of the data to another; it’s not if you want to add a lot of surrounding markup and things like a sitemap and similar navigation tools. This is next to impossible in pure XSLT, it gets better once you have some extensions (dubbed EXSLT, and supported by pretty much any xslt processor) or maybe with XSLT2. String manipulation is also a pain (at least with XSLT1); I gave up on generating a nice “last modified” date from my subversion tag. Supposedly XSLT2 has some functions that could make this easier (i.e. for parsing and printing datetime information), but the common approach with XSLT is to only supply the required minimum of function you need, and I’m not aware of an easy way to add custom functions, not to mention any large standard library that can efficiently be used (which is the true strength of Java, Python and C#, that they bring a huge collection of pre-written ready-to-use code with them). Of course there are some efforts to write XSLT libraries (especially for XSLT2), and this aforementioned EXSLT is some kind of standard library that even might be efficiently implemented in some interpreters - you can’t rely on it to be there and to just work. XSLT isn’t useless, but when it comes to presenting data to humans or writing clean, compact code it’s not satisfactory at all.

I’d give you my Makefile and XSLT file, if they weren’t that messy… too many features; I’m generating two languages, a partially expanded navigation menu, etc. - my XSLT is 10k, my sitemap currently 4.5k, the template file is 5k.

Anyway. Half a year ago, my favourite templating language was KID templating. I used it for some small projects such as my DNSoupdate tool to edit DNS zones via the DNS protocol (requires a nameserver such as bind which has support for DNS update, uses encryption). It was a perfect match for such tiny pages, but I’m no longer that convinced I still like it for larger projects.

What’s good about Kid: XML templating language, Python based, easy to use in whichever way you want by writing a few lines of python (i.e. easy to write a Makefile to generate a static version of you homepage)

What’s not good about Kid: only works with a Python interpreter. I’d prefer to have a templating language that can be used from multiple languages. However the Kid syntax relies on Python, which is really bad. Also I’d prefer to have some component-render model for more complex websites. The current setup is IMHO okay if you have one default layout and one content layout; but if you have multiple components that could be combined differently on the pages, it gets too messy. With my turbogears experiments, Kid was also not very performant (but that might as well be Turbogears fault).

Right now, I’d probably still go with Kid. But I’ve been having a look at JSP 2.1, and JSF / Facelets in particular. There are some things about facelets that I really like (for example, that they use a proper XML syntax, instead of this bastardized almost-XML that JSP usually (ab-)uses). There is also some stuff that I don’t like (e.g. the massive overengineering of everything surrounding it), and I have no idea how easy it will be to generate static pages in a scripted fashion, i.e. using it without a real webserver. Or I might just write it all in python, which is a nice language for manipulating XML, usually.

Please don’t just send me an email with your favourite templating engine. Like zack, I’m only interested in XML-based templating engines, which does not apply to most templating solutions out there. Clearsilver for example is another bastardization of XML. I’m aware of TAL/METAL, and find them quite interesting, but they were also not having this kind of componentization that I’m usually thinking in.

[Update: some people have pointed me to Genshi, which is mostly Kid compatible. However, it still has mostly the same problems, e.g. the templates being not reusable in other languages than python, and that certain constructs are a pain to do (e.g. the page_specific_css recipe with more than one css file). Others have pointed me to smarty, but it’s string-based and doesn’t ensure valid XML output. (Which is very useful for e.g. generating atom or rss output) For example this is probably valid in smarty: {if 0}<b>{/if}</b> - allowing errors is bad. Oh, and smarty is PHP, which is broken by design, a no-go. The best match to my ideas so far is XML::Template (for Perl, Python, Ruby, PHP) which is pretty close to what I’ve been doing manually when not using a templating solution. I don’t know yet how well it handles recursion - I need recursive templates for the navigation menu on my homepage.]