Cannot delegate multiple interfaces on a given class

[Aaron Bentley]

If delegates is used twice in a class definition, things explode:
$ ./test.py -v test_branchmergeproposal -t ReviewDiffJob
Traceback (most recent call last):
  File "./test.py", line 175, in ?
    from canonical.testing import profiled
  File "/home/abentley/launchpad/web-bmp-diffs/importfascist.py", line 155, in import_fascist
    module = original_import(name, globals, locals, fromlist)
  File "/home/abentley/launchpad/web-bmp-diffs/lib/canonical/testing/__init__.py", line 67, in ?
    from canonical.testing.layers import *
  File "/home/abentley/launchpad/web-bmp-diffs/importfascist.py", line 155, in import_fascist
    module = original_import(name, globals, locals, fromlist)
  File "/home/abentley/launchpad/web-bmp-diffs/lib/canonical/testing/layers.py", line 87, in ?
    from canonical.launchpad.testing.tests.googleserviceharness import (
  File "/home/abentley/launchpad/web-bmp-diffs/importfascist.py", line 155, in import_fascist
    module = original_import(name, globals, locals, fromlist)
  File "/home/abentley/launchpad/web-bmp-diffs/lib/canonical/launchpad/testing/__init__.py", line 16, in ?
    from canonical.launchpad.testing.factory import *
  File "/home/abentley/launchpad/web-bmp-diffs/importfascist.py", line 155, in import_fascist
    module = original_import(name, globals, locals, fromlist)
  File "/home/abentley/launchpad/web-bmp-diffs/lib/canonical/launchpad/testing/factory.py", line 31, in ?
    from canonical.launchpad.database.message import Message, MessageChunk
  File "/home/abentley/launchpad/web-bmp-diffs/importfascist.py", line 155, in import_fascist
    module = original_import(name, globals, locals, fromlist)
  File "/home/abentley/launchpad/web-bmp-diffs/lib/canonical/launchpad/database/__init__.py", line 17, in ?
    from canonical.launchpad.database.product import *
  File "/home/abentley/launchpad/web-bmp-diffs/importfascist.py", line 155, in import_fascist
    module = original_import(name, globals, locals, fromlist)
  File "/home/abentley/launchpad/web-bmp-diffs/lib/canonical/launchpad/database/product.py", line 32, in ?
    from canonical.launchpad.database.branch import BranchSet
  File "/home/abentley/launchpad/web-bmp-diffs/importfascist.py", line 155, in import_fascist
    module = original_import(name, globals, locals, fromlist)
  File "/home/abentley/launchpad/web-bmp-diffs/lib/canonical/launchpad/database/branch.py", line 70, in ?
    from canonical.launchpad.database.branchmergeproposal import (
  File "/home/abentley/launchpad/web-bmp-diffs/importfascist.py", line 155, in import_fascist
    module = original_import(name, globals, locals, fromlist)
  File "/home/abentley/launchpad/web-bmp-diffs/lib/canonical/launchpad/database/branchmergeproposal.py", line 799, in ?
    class ReviewDiffJob(object):
  File "/home/abentley/launchpad/trunk/lib/zope/interface/advice.py", line 132, in advise
    return callback(newClass)
  File "/usr/lib/python2.4/site-packages/PIL/__init__.py", line 77, in _delegates_advice

KeyError: '__delegates_advice_data__'

There should be a way to delegate multiple interfaces. Ideally, by invoking delegates twice in a class definition, so that varying contexts can be used.

It would also be nice to be able to delegate all interfaces provided by a context object, also. This would help when using delegates as a form of pseudo-inheritance.

[Curtis Hovey (sinzui)]

I have experienced this too. I agree this would be a nice feature for composing classes of many small parts. I believe the delegates() requires an additional argument that provides a namespace for the private attributes. This may be implicitly knowable using context, because only one delegate can use the context attribute, any other would need to use another attribute.

[Barry Warsaw (barry)]

With Gary's MP landed 5+ years ago, I think this bug is fixed! If you disagree, please re-open.