[Twisted-web] Slot/pattern/key changes

[Matt Goodall]

On Tue, 2004-02-10 at 21:30, James Y Knight wrote:
> This is a set of *BACKWARDS-INCOMPATIBLE* changes that simplifies and 
> clarifies the set of attributes nevow has for finding elements. Tests 
> pass, and my app works (both after being updated slightly for the API 
> changes).
> 
> There used to be 3 attributes you could put on elements to locate them: 
> slot, pattern, and key. They all did similar but slightly different 
> things.
> 
> - Filling slots with data is a useful concept but 'slot' shouldn' t be 
> an attribute. A slot is something that gets replaced with the given 
> data, and is thus better as a standalone element. It has been replaced 
> with the following:
> slot('slotname') in a stan tree, or <nevow:slot name="slotname" /> in 
> an (X)HTML template.
> context.slotted() (which could locate a slot) has been eliminated and 
> replaced with context.fillSlots(slotname, stantree). Note that you 
> cannot locate slots, you can just specify data for them to fill 
> themselves with.
> 
> - Assigning unique keys is also a useful concept, but it doesn't 
> require the "context.keyed()" method. That method has been eliminated. 
> HTMLRenderer used it to find the key="content" in HTML files used as 
> sub-renderers, now it uses pattern="content".
> 
> - Patterns remain as the only way to locate a sub-element of your 
> renderer. There are now 3 methods to locate them, depending on what you 
> want to do. patternGenerator() replaces patterns(), onePattern() 
> semi-replaces keyed(), and allPatterns() replaces the direct use of 
> specialMatches that the sequence renderer previous did. Please see the 
> docs in context.py for these three methods for precise behavior.
> 
> So, in summary, to convert your old code to new code:
> 1) If you had "div(style="border:1px", slot="myslot")" replace it with 
> div(style="border: 1px")[slot("myslot")].
> 2) If you had a template with "<div style="border:1px" 
> nevow:slot="myslot" />" replace it with "<div 
> style="border:1px"><nevow:slot name="myslot" /></div>
> 3) If you had "context.slotted("myslot").clear()[a(href="foo")["bar"]] 
> replace it with context.fillSlot("myslot", a(href="foo")["bar"]]
> 4) If you used keyed(), convert key= to pattern= and keyed() to 
> onePattern().
> 5) If you used patterns(), just rename it to patternGenerator()

I have one more use case that is not possible/easy with the proposed
change:

HTML:
<a nevow:slot="email" class="whatever" href="email:">email</a>

Rendered by:
context.slotted('email')(href=['mailto:','a@bc.com'])['Mr X']

Result:
<a class="whatever" href="email:a@bc.com">Mr X</a>

> 
> Also included in this patch are doc cleanups, removing excess xml() 
> wrappings, replacing yield by return when possible, and the ability to 
> use the "<nevow:invisible>" element in a (x)html template file, with 
> the same behavior as the invisible stan tag.
> 
> James
-- 
Matt Goodall, Pollenation Internet Ltd
w: http://www.pollenation.net
e: matt@pollenation.net

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