[Zope] Re: what's the difference between metal:block and tal:block?

[Gerry Kirk]

J Cameron Cooper wrote:
>>

> 
> One uses these when there's no obvious or necessary tag in which to put 
> a METAL or TAL declaration. It's quicker to write than a div/span plus a 
> tal:omit-tag.
> 
> Note that the name of the tag after the namespace (block) can really be 
> anything. But 'block' seems to be our de facto standard.
> 
>          --jcc

JCC,

I guess I understand the syntax part of the question, but what I don't 
understand is why in some cases a METAL declaration is needed. Let me 
give you an example, a code snippet from a stock Plone site. This code 
is inside a <metal:block define-macro>:

<tal:block tal:condition="no_types">

     <select id="filter_selection"
             name="filter_by_portal_type:list"
             style="float: left"
             onChange="submitFilterAction()"
             tabindex=""
             tal:attributes="tabindex tabindex/next|nothing;">

         <option value="#"
                 tal:attributes="selected
                 python:test((len(filterTypes)>1 or 
len(filterTypes)==0), 'selected', '');"
                 i18n:translate="label_show_all_items">
         Show All Items
         </option>


         <metal:block tal:repeat="type types">
             <option value="#"
                     tal:define="typetitle type/Title; typeid type/getId"
                     i18n:translate="label_show_x_only"
                     tal:attributes="value typeid;
                                     selected python:test( 
len(filterTypes)==1 and (typeid in filterTypes), 'selected', '');"
             ><span i18n:name="type"><span i18n:translate="" 
tal:content="string:${typetitle}" tal:omit-tag="" /></span>s only</option>
         </metal:block>


     </select>

     <input type="hidden" name="filter_by_Subject:tokens" value="" />
     <!--you can filter by subject keywords by filling in this value-->

</tal:block>

TIA,
Gerry