"Peter Royal" <[EMAIL PROTECTED]> wrote: > On Wednesday, June 18, 2003, at 05:53 PM, Pier Fumagalli wrote: >> Unless I'm not mistaken, the above example template is _NOT_ a well >> formed >> XML document! :-) :-) > > Of course! I guess it was more of a, "why (nearly) re-invent the > wheel".. But obviously it was to escape the XML syntax :)
Well, there are several advantages in not using XML as the storage datatype for templates. The first objective I am trying to achieve is a simpler and light-weight syntax. Of course the Jelly people thought about it, given that in their documents availabe at <http://jakarta.apache.org/commons/jelly/overview.html> they write (quote): > "Jelly could have a surface syntax that looks similar to Velocity. i.e. > someone could make a parser of Jelly that had a look-and-feel of Velocity for > common directives and expressions." Now, what do I mean by "simpler" sintax? Imagine, for example a "foreach" statement: In XML (or better XSLT, but at the end of the day it'll have to apply to any possible template which is based on XML) it looks quite ugly, to my standards: <ul> <xsl:foreach select="parameters"> <li><xsl:value-of select="@name"/>: <xsl:value-of select="@value"/></li> </xsl:foreach> </ul> If you've ever used (and liked) velocity, for instance, you'd write something MUCH simpler, and in garbage (which is basically Velocity with Xpath), the same exact construct will become something like: <ul> #foreach {parameters} <li>[EMAIL PROTECTED]: [EMAIL PROTECTED]</li> #end </ul> Sorry if I like the latter :-) Now, if you see an if/else-if/else statement, XSLT looks like: <div> <xsl:choose> <xsl:when test="parameter/@name = 'primary'"> <span class="red"><xsl:value-of select="parameter/@name"/>: </span> </xsl:when> <xsl:when test="parameter/@name = 'secondary'"> <span class="green"><xsl:value-of select="parameter/@name"/>: </span> </xsl:when> <xsl:when test="parameter/@name = 'tertiary'"> <span class="green"><xsl:value-of select="parameter/@name"/>: </span> </xsl:when> <xsl:otherwise> <span><xsl:value-of select="parameter/@name"/>: </span> <xsl:otherwise> </xsl:choose> <xsl:value-of select="parameter/@value"/> </div> This is IMVHO a huge pain if compared with the following: <div> #if {parameter/@name = "primary"} <span class="red"> #elif {parameter/@name = "secondary"} <span class="green"> #elif {parameter/@name = "tertiary"} <span class="green"> #else <span> #end [EMAIL PROTECTED]:</span> [EMAIL PROTECTED] </div> Ok, ok, I could have written the above as: <div> <span> <xsl:choose> <xsl:when test="parameter/@name = 'primary'"> <xsl:attribute name="class">red</xsl:attribute> </xsl:when> <xsl:when test="parameter/@name = 'secondary'"> <xsl:attribute name="class">green</xsl:attribute> </xsl:when> <xsl:when test="parameter/@name = 'tertiary'"> <xsl:attribute name="class">blue</xsl:attribute> </xsl:when> </xsl:choose> <xsl:value-of select="parameter/@name"/>: </span> <xsl:value-of select="parameter/@value"/> </div> (which I don't know if it's easier, I just have to maybe set the class in a span depending on the name of a parameter)... But still, this is way too complicated for me (maybe not to write, but to read). Also, the use of "<xsl:attribute ...>" will not allow us to start processing the "<span>" element until that is closed, as the "<xsl:attribute>" might be right at the end (and if that span contains something like 2 megs of data, well, you see where I'm going to... And on, and on, and on... Now, why Velocity ain't good for Cocoon IMVHO? It's stream based, and it's expression library is not something that will help me to introduce my graphic team to all the rest of the wonders of Cocoon. Basically, yes, I reinvented the wheel... I took two of the different approaches used in the Cocoon PetStore for the view (JXPath and Velocity, which I liked better), added few bits of what Stefano said in his "[RT] the quest for the perfect template language", consulted XQuery, but Scott is a very bad driver and uses to many curly braces (and I go nuts), shakered, added salt and pepper, built and climbed a tree, parsed the garden with JavaCC, and puff... Here comes out the trash... Pier
