Transition mini-HOWTO

Notes

A few bullet points with stuff to do transitioning from pre-dependency code to the new API(s).

• axiom.item.InstallableMixin has been removed since it is unnecessary, as is the installedOn attribute that was on subclasses thereof. powerup.installedOn() is now spelled axiom.dependency.installedOn(powerup).
• powerup.installOn(target) is now spelled axiom.dependency.installOn(powerup, target). See also axiom.dependency.uninstallFrom(powerup, target).
• Instead of explicitly powering the target up in installOn, set the powerupInterfaces class attribute to a sequence of interfaces, or of (interface, priority) tuples.
• If you are implementing INavigableElement, you need something like:

  privateApplication = dependsOn(PrivateApplication)
  

• Declare other dependencies of your powerups as appropriate.
• Get rid of your Benefactor / BenefactorFactory classes, and instead pass an installablePowerups sequence when constructing your offering. For example:

  installablePowerups = [
      (u'Operator admin', u'Operator administration', OperatorAdmin),
      (u'Reports', u'Data reporting functionality', Reports),
      ]
  

• TODO: writing upgraders

Example

xmantissa.webapp was migrated as part of this change. That serves as a good example, and will be (incompletely) presented below as a demonstration. The examples below elide most of the code and focus just on the changes. Please refer to the different file versions themselves for a complete representation.

Before (reference):

class PrivateApplication(Item, PrefixURLMixin):
    ...
    implements(ISiteRootPlugin, IWebTranslator)
    ...
    installedOn = reference()
    ...
    def installOn(self, other):
        super(PrivateApplication, self).installOn(other)
        other.powerUp(self, IWebTranslator)

        def findOrCreate(*a, **k):
            return other.store.findOrCreate(*a, **k)

        findOrCreate(StaticRedirect,
                     sessioned=True,
                     sessionless=False,
                     prefixURL=u'',
                     targetURL=u'/'+self.prefixURL).installOn(other, -1)

        findOrCreate(CustomizedPublicPage).installOn(other)

        findOrCreate(AuthenticationApplication)
        findOrCreate(PreferenceAggregator).installOn(other)
        findOrCreate(DefaultPreferenceCollection).installOn(other)
        findOrCreate(SearchAggregator).installOn(other)
    ...

After (reference):

class PrivateApplication(Item, PrefixURLMixin):
    ...
    implements(ISiteRootPlugin, IWebTranslator)
    ...
    powerupInterfaces = (IWebTranslator,) 
    ...
    customizedPublicPage = dependsOn(CustomizedPublicPage)
    authenticationApplication = dependsOn(AuthenticationApplication)
    preferenceAggregator = dependsOn(PreferenceAggregator)
    defaultPreferenceCollection = dependsOn(DefaultPreferenceCollection)
    searchAggregator = dependsOn(SearchAggregator)