Hi Alfred, On Dec 4, 2006, at 12:46 PM, Alfred Nathaniel wrote:
Or use different tags, say in resemblance to XSLT: <map:if path="..."> ... </map:if> <map:choose> <map:when path="...">
I'm not so keen on that, 'cause I'm actually trying to get away from using 2 different elements for this. Rationale:
1) The precedent of <match> and <select> would have conditioned users to interpret <if> and <choose> as referring to two different kinds of sitemap components ("Iffer"s and "Choose"rs? :-). I'd like the syntax to emphasize that it's all matching and there is only one component now, The Matcher.
2) The sitemap language is not XSLT and has nothing to do with XSLT. The only relationship is that the sitemap has to do with Cocoon and Cocoon uses XSLT... big deal! :-) Trying to imitate XSLT in the sitemap in the interest of familiarity IMHO is misguided and results in confusion. Things that are different should look and feel different. For example: in XSLT <if> and <choose>, the @test clause contains a predicate. This is fundamentally different then in the sitemap, where the corresponding attribute contains a pattern, and the predicate comprises some kind of (implicit or configured) match of this pattern against a configured target value. Now the way this is expressed in the "classic" sitemap, the <select/when> version puts this value into an attribute called "test" — probably, again, in deference to XSLT, and IMHO confusing — while the <match> version puts it in an attribute called "pattern". But in either case, the semantics are rather different than XSLT owing to the difference between "predicate" and "pattern".
3) I think XSLT got it wrong :-). They should have used something like "<xsl:cond>" for both, and treated @test like I treat @value in my proposal. An analogy between <xsl:choose> and a "switch" or "case" statement is flawed, the correct analogy is to "if()... else if()" — again, because of the distinction between predicate and pattern! Switch/case is really like today's <map:select>!!! "if()..." inaugurates a conditional using the same keyword regardless of how many alternatives there are — one, or many. That's how sitemap matching (which has only patterns) should do it, and that's how XSLT (which has only predicates) should have done it. No need for two different keywords.
cheers and thx for the feedback :-), —ml—
