dm.zope.schema 1.0

Modules

Examples

Setup: It defines two schemas S1 and S2, an interface I and a class C deriving from SchemaConfigured implementing the schemas and the interface.

>>> from zope.interface import Interface, implements, providedBy
>>> from zope.schema import Int
>>>
>>> from dm.zope.schema.schema import SchemaConfigured, schemadict
>>> from dm.zope.schema.verify import verify_schema
>>>
>>> class S1(Interface): i1 = Int(default=0)
...
>>> class S2(Interface): i2 = Int(default=1)
...
>>> class I(Interface):
...   def method(): pass
...
>>> class C(SchemaConfigured):
...   implements(S1, S2, I)
...   def method(self): pass
...

C instances have attributes corresponding to the schema fields. If no arguments are given for the constructor, they get the field default as value. Provided (keyword!) arguments override the defaults.

>>> c = C()
>>> c.i1
0
>>> c.i2
1
>>> c = C(i1=5)
>>> c.i1
5

The constructor rejects keyword arguments not defined in the schema in order to quickly detect spelling errors. However, this hampers the use of super in the class hierarchy for the __init__ method. Maybe, future versions will provide a means to control this check.

>>> c = C(x=5)
Traceback (most recent call last):
  ...
TypeError: non schema keyword argument: x

If the field values are appropriate, C instances provide the schemas (as verified by verify_schema). Otherwise, verify_schema will raise an exception. This example should also the elementary use of verify_schema.

>>> verify_schema(S1, c)
>>> c.i1=None
>>> verify_schema(S1, c)
Traceback (most recent call last):
  ...
zope.schema.interfaces.WrongContainedType: [('i1', RequiredMissing())]