[Zope-CMF] addActionProvider

[Tres Seaver]

On Tue, 2002-08-27 at 04:51, Thomas Olsen wrote:
> On Tuesday August 27 2002 10:24, Thomas Olsen wrote:
> >     def addActionProvider( self, provider_name ):
> >         """ add the name of a new action provider """
> >         if hasattr( self, provider_name ) \
> >           and not provider_name in self.action_providers:
> >             p_old = self.action_providers
> >             p_new = p_old.append(provider_name)
> >             self.action_providers = p_new
> 
> Oops - this made me loose all my action providers.
> This seems to work a bit better:
> 
>     def addActionProvider( self, provider_name ):
>         """ add the name of a new action provider """
>         ap = self.action_providers
>         if type(ap) is not type([]) and type(ap) is not type(()):
>             ap = []
>         if hasattr( self, provider_name ) \
>           and not provider_name in ap:
>             ap.append(provider_name)
>             self.action_providers = ap

We *really* want self.action_proviers to be a tuple, not a list, to
avoid issues with mutable attributes shared between the class and the
instance. Some tools created before 1.3 did have lists;  here is how I
would accomodate these tools:
 
     def addActionProvider( self, provider_name ):
         """ add the name of a new action provider """
         ap = self.action_providers
         if type(ap) is not type([]) and type(ap) is not type(()):
             ap = []
         ap = list(ap)[:] # Get a totally fresh copy
         if hasattr( self, provider_name ) \
           and not provider_name in ap:
             ap.append(provider_name)
             self.action_providers = tuple(ap)

BTW, I think Gitte Wang reported the same problem to the collector:

  http://collector.zope.org/CMF/42

Tres.
-- 
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Tres Seaver                                tseaver@zope.com
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