Re: Template engine

From:
 Daniel Pitts <googlegroupie@coloraura.com>
Newsgroups:
comp.lang.java.programmer
Date:
Thu, 16 Aug 2007 15:17:02 -0000
Message-ID:
<1187277422.716674.32070@i38g2000prf.googlegroups.com>
On Aug 15, 11:07 am, Artur Siekielski <artur.siekiel...@gmail.com>
wrote:

Or perhaps they can all be wrappers that contain that information
dynamically.

class Variable<T> {
   T value;
   Validator<? super T> validator;
   RenderType renderType;

};

I would think that this is the most useful and flexible approach, but
maybe thats just me.


This approach facilitates simulation of declaration of types:
<template-code>
set $i.type = 'integer'
set $e.type = 'enum(one, two, three)'

You set i to $i.value and e to the number $e.value
</template-code>

It's quite good, but using '$i.value' instead of '$i' is error prone
and a it's a kind of hack (template code must be as simple as
possible, because it will be created by nonprogrammers). But it's a
very nice idea, thanks.
I'm also considering XSLT, it would look like that:
<template-code>
You set i to <xsl:value-of select="//var[@name='i' and
@type='integer']"/> and e to the number <xsl:value-of select="//
var[@name='e' and @type='enum(one, two, three)']"/>.
</template-code>
But verboseness of XML is very discouraging...

I also have to parse template and get names and types of variables.
When using XSLT it's a bit easier, because I can parse it with XML and
XPath parsers. I don't know if Velocity or Freemarker have parsers
accessible from user code...


or, if the type is really determined at the template level (instead of
at the model level passed too the template), then perhaps what you
really want is to be able to update the model from the template, so
that the template can set the "type" of the variable...

Also, if you care about the difference between e.value and e...

public String toString() {
   return renderType.render(value);
}

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