Re: RFC: Proposal Dexterity API - two variants

Any api that has attribute assignment ie context.blah = 'value' will not work in restricted python and can't be used in ZPT, python scripts or Plomino plus a few dozen other places where restricted python is used. 


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On 5 Nov 2014, at 4:44 pm, Jens W. Klein <jens-/[email protected]> wrote:

> ======================
> Proposal Dexterity API
> ======================
> 
> We, Robert Niederreiter and Jens Klein, wrote this proposal as an entry 
> to a discussion for an future Dexterity API (read: Dexterity 3). We 
> followed two different pathes and we are curios which one gets more +1 ;)
> 
> Both of them are implementable and also both are in the perspective of 
> speed almost the same.
> 
> 
> Explicit behaviors proposal: expose behaviors explicitly
> ========================================================
> 
> Basic principles
> ----------------
> 
> * Duplicate attribute names are allowed by different behaviors
> * Programmer always addresses effected behavior explicit
> 
> 
> Pros
> ----
> 
> * More reliable and readable code
> * Explicitness
> * Easy migration
> 
> 
> Cons
> ----
> 
> * Steeper learning curve (developer needs to learn which behaviors exists)
> * More code
> 
> Implementation implications
> ---------------------------
> 
> * think of behavior inheritance and how default behaviors can be overwritten
> 
> 
> API usage example
> -----------------
> 
> Read Attribute::
>>>> context.behavior('basic').title
> 
> Write Attribute::
>>>> context.behavior('basic').title = u'My Title'
> 
> Behavior information::
>>>> context.behaviors
> {
>     'basic': {
>         'title': 'Basic',
>         'description': 'Foo',
>         'attributes': {
>             'title': {
>                 'label': 'Title',
>                 'description': 'Title of the object',
>                 '...'
>             },
>             ...
>         }
>     }
>     ...
> }
> 
>>>> repr(context.behaviors)
> - basic
>     -title
>     -description
> ...
> 
> Unrestricted access::
>>>> context.behavior('basic').unrestricted('title')
> 
> 
> Shadowed Behaviors Proposal: Simplified value access
> ====================================================
> 
> Basic principles
> ----------------
> 
> * implemented as one property directly on 
> plone.dexterity.content.DexterityContent which acts as a 
> zope.interface.mapping.IFullMapping (read: dict-like) to work with all 
> values and methods coming from the main schema, behavior schemas and 
> behavior factories.
> * Programmer does not need to know about behavior names when accessing data
> * Set/get of main schema values is same as schemas form behaviors.
> * Duplicate attribute names are NOT allowed any more and enforced 
> (checked on FTI creation time, i.e. XML import, TTW setting) This is 
> important!
> * factory methods/properties from behaviors are exposed when a factory 
> is given instaed of direct attribute access.
> 
> 
> Pros
> ----
> 
> * Simple entry for new developers
> * pythonic
> * natural dict-like API is first principle
> * no accicdential override of attributes stored
> * behavior inheritance (i.e.IDublicCoreMetadata is not a problem at all)
> 
> 
> Cons
> ----
> 
> * duplicate fieldnames in existing code needs migration (not in core)
> * behaviors are kind of hidden to developers, so misunderstandings may 
> occur (needs good documentation)
> 
> 
> Open for discussion
> -------------------
> 
> * should validation be enforced?
> 
> 
> Important
> ---------
> 
> * lots of caching of schemas and intermeidate results
> 
> 
> API usage example
> -----------------
> 
>>>> context.values['title']
> 'My Document'
> 
>>>> context.values['title'] = 'Jensens Document'
>>>> context.values['some_factory_property'] = 'Foo'
>>>> context.values['some_factory_property']
> 'Foo'
> 
>>>> context.values['some_factory_method'](param1, param2='foo')
> ...
> 
>>>> context.values.keys()
> ['title', 'description', ....]
> 
>>>> context.update({'title': 'Jensens Updated Document', 'description': 
> 'A new easy to understand API for dx'}
>>>> context.values.items()
> [('title': 'Jensens Updated Document', 'description': 'A new easy ...', 
> ....)]
> 
> other dict-api methods are implemented too (need to finish this, but you 
> can imagine how it looks like, )
> active access to restricted values which checks the read/write permission!
> 
>>>> context.restricted_values['title']
> Traceback ...
> ....
> Unauthorized(...)
> 
> 
> Legacy Proposal
> ------------------------
> 
> * rename dexterity to devilstick
> * use wording molecule instead of behavior
> * the values are atoms
> * ignore this legacy proposal ;D
> 
> -------------------------------------------------------------------------
> 
> happy commenting
> 
> Jens and Robert
> -- 
> BlueDynamics Alliance
> 
> 
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