[Zope-CMF] Re: [dev] enhancing Actions: a rough proposal

[yuppie]

Hi Kapil!


Kapil Thangavelu wrote:
> okay. could you elaborate on what sort of extensions or use cases are
> possible with this new model, that currently can't be implemented?
> the only ones i've seen advanced are relating to have a central location
> for ui based action manipulation. and even this seems not nesc true if
> workflow and type actions are going to be manipulated separately, ie. if
> compatiblity with existing providers is going to be maintained, and
> instead there will be need be two models, which is fine by me ie. if
> existing functionality and action provider impl can be preserved.

Using Actions that subclass from SimpleItemWithProperties...

- makes it easier to create custom Action classes with custom properties

- makes it easier to implement property schemas based on PropertySheets, 
see this thread for a related discussion:
http://mail.zope.org/pipermail/zope-cmf/2004-September/021307.html


Using providers and categories that subclass from OrderedFolder...

- allows to plug in custom Actions and categories

- allows to use all the standard methods to add/copy/move/sort Actions 
and categories

- makes it easy to create hierarchical menus using subcategories


Moving all Actions into one central ActionProvider...

- makes the ActionIconsTool redundant

- clears up the ZMI

> in terms of negatives and feature removal of this proposal, removing
> action providers for, means to me replacing dynamic capabilities of
> action providing by the application, in favor of relying on action level
> tales filtering. using different action category implementations can
> possibly compensate somewhat but the with the additional restriction on
> category.
> 
> say for example, i have a versioning tool that provides a set of
> multicategory actions based on whether or not the content is
> versionable. if i want to dynamically provide actions based on context,
> with the new mechanism, i would need to register relevant actions with
> each action category. with the old model a tool could do a simple check
> in restricted code and disable the whole action set if its not
> versionable.  

Do you know of many tools that work like that? Do they have to share 
many categories with other Action providers?

> or say i have content with dynamic actions based on object state (a
> workspace with/ actions based on installed plugins or direct action
> manipulation on the content for example), with the new model i'd have to
> do it based on tales expressions that would need to be evaluated in the
> context of all content, as opposed to the relevant instance. 

That's a similar problem as with type Actions and workflow Actions. I 
believe that these tools should still control which Actions are 
available, but not the properties of these Actions.

A simple implementation of that would be using condition expressions 
that call a method of the tool. But I'm optimistic there is a faster 
solution that works with simpler expressions or without. I don't think 
this has to be resolved before we convert normal Actions.


Cheers,
	Yuppie