[Zope3-dev] Re: tal:define="..." considered harmful?

Jean-Marc Orliaguet jmo at ita.chalmers.se
Wed Feb 15 11:20:23 EST 2006

Benji York wrote:

> Martijn Faassen wrote:
>> Right, that was my motivation too - I googled around for 
>> javascript-based templating languages but realized there wasn't 
>> really anything. Of course XSLT can be used this way too, but TAL is 
>> kinda neat too. Still, I couldn't think of much practical use for 
>> this. Perhaps in this AJAXy world this has changed.
> Personally I'm very excited about ctal (and like the name too).  
> Getting data objects from the server and feeding them to templates on 
> the client seems like a nice way to do AJAXy things.

yep, you can also use TAL (ZPT) to create CTAL templates; that's the 
reason why I think the namespace is ctal:... and not tal:..., otherwise 
it could as well have been called tal:... and the template be stored in 
a string.

then there are different usage patterns,
personally I download the template from the server when the page is 
getting initialized (using asynchronous Ajax.request) and I store the 
source in a javascript variable in a widget class. To render the 
template I apply the transformation whenever the data changes. It makes 
it possible to refresh widgets, otherwise you'd have to refresh the page 
or redo an Ajax.request.

here is the part of the code that does the rendering:

render: function(data) {
  if (this.source) {
    var node = document.createElement("div");
    node.innerHTML = this.source;
    ctal.process_ctal(node, data);
    var old_html = this.widget.innerHTML;
    var new_html = node.innerHTML;
    if (new_html != old_html) {
      this.widget.innerHTML = node.innerHTML;

the performance is quite fine actually, but since this is event-driven I 
should first check that the data really has been changed before firing a 
"modified" event, to avoid rendering the template for nothing.

I think 'ctal' is fine too. (client tal)


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