[Zope-CMF] CMF add views and <browser:page />

[Martin Aspeli]

Martin Aspeli wrote:
> Hi Yuppie,
> 
>>>> It is not obvious why you have to use explicit Zope 2 style security for 
>>>> add views and declarative Zope 3 style security for other views. But I'd 
>>>> rather like to see the 'permission' attribute of <adapter /> implemented 
>>>> for Zope 2 instead of a new <cmf:addview /> directive.
>>> Mmmm... I'm not sure most people would find it natural to think about 
>>> the add form as an adapter like this.
>> Well. I find it natural to think about browser pages as a special kind 
>> of adapters. 
> 
> Having explained this to a lot of different people with different levels 
> of experience, I think "natural" is too strong a word for most people. 
> The fact that browser views are adapters is an implementation detail 
> that often give people an "aha!" type reaction when they really 
> understand it. However, a lot of people will use browser views for a 
> long time without really understanding adapters (if they ever do or care).
> 
>> And since add forms don't fulfill all the special criteria 
>> for <browser:page />, we have to fall back to the more generic <adapter />.
> 
> Right. But there's a reason why <browser:page /> is "special". 
> Logically, views and adapters are quite different things, and, of 
> course, <browser:page /> does a lot more than just register an adapter.
> 
>>> Also, Five's <browser:page /> does quite a lot of stuff that we now 
>>> can't have for CMF add views:
>>>
>>>      o It allows a template to be registered
>>>      o It allows an attribute other than __call__ to be used to render 
>>> the view
>>>      o It sets up security on attributes, by interface or explicit list
>>>      o It sets up security on the view class itself
>> Sure. The question is: Do we really need these features for add views?
>>
>>> I don't think the adapter permission attribute would be sufficient in 
>>> any case. In Zope 3, it's tied to a type of low-level security proxy 
>>> that doesn't really exist in Zope 2. The ClassSecurityInfo stuff only 
>>> affects restricted python/traversal, whereas Zope 3 security proxies are 
>>> applied everywhere.
>> AFAICS I didn't register the add views correctly. Provided interface 
>> should be IBrowserPage or IPageForm, not IBrowserView.
>>
>> Given that, in the Zope 3 world <adapter />'s 'permission' attribute and 
>> <browser:page />'s 'permission' attribute would do the same: Creating a 
>> security checker that protects 'browserDefault', '__call__' and 
>> 'publishTraverse' by the specified permission. Or am I missing something?
> 
> I'm not sure. Zope 2 doesn't really have a concept of security outside 
> restricted python/traversal, so the translation form Zope 3 is always 
> going to be a bit odd.
> 
>> Currently this is not true for Zope 2. While Five implements Zope 2 
>> specific behavior for <browser:page />'s 'permission' attribute, the 
>> same attribute of <adapter /> is useless in Zope 2.
> 
> I wonder why this is, though. There's probably a reason why the Five 
> developers didn't want to extend the security stuff to the <adapter /> 
> registration.
> 
>> I can't see a fundamental problem in using the generic adapter directive 
>> for registering browser pages. I just see limited support for the 
>> adapter directive in Zope 2. As long as these issues are not resolved, I 
>> can live with Zope 2 security declarations in add views.
> 
> FWIW, I think this'll work:
> 
>      <adapter
>          for="Products.CMFCore.interfaces.IFolderish
>               zope.publisher.interfaces.browser.IBrowserRequest
>               ..interfaces.IDexterityFTI"
>          provides="zope.publisher.interfaces.browser.IBrowserView"
>          factory=".add.DefaultAddView"
>          />
>      <class class=".add.DefaultAddView">
>          <require
>              permission="cmf.AddPortalContent"
>              interface="zope.publisher.interfaces.browser.IBrowserView"
>              />
>      </class>
> 
> I don't much like it, though. :-/
> 
> I'd wager this is a lot closer to what people would expect:
> 
>    <cmf:addview
>       for="Products.CMFCore.interfaces.IFolderish"
>       fti="..interfaces.IDexterityFTI"
>       class=".add.DefaultAddView"
>       permission="cmf.AddPortalContent"
>       />

Meh - of course, I meant:

     <cmf:addview
        name="my.type"
        for="Products.CMFCore.interfaces.IFolderish"
        fti="..interfaces.IDexterityFTI"
        class=".add.DefaultAddView"
        permission="cmf.AddPortalContent"
        />

Martin

-- 
Author of `Professional Plone Development`, a book for developers who
want to work with Plone. See http://martinaspeli.net/plone-book