author | Sverre Rabbelier <srabbelier@gmail.com> |
Sat, 31 Jan 2009 12:35:40 +0000 | |
changeset 1103 | 794162cfca92 |
parent 323 | ff1a9aa48cfd |
permissions | -rw-r--r-- |
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Major reorganization of the soc svn repo, to merge into a single App Engine
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""" |
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Convenience routines for creating non-trivial Field subclasses. |
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parents:
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|
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Add SubfieldBase as the __metaclass__ for your Field subclass, implement |
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to_python() and the other necessary methods and everything will work seamlessly. |
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parents:
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""" |
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Load ../vendor/django into trunk/app/django.
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class SubfieldBase(type): |
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""" |
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Todd Larsen <tlarsen@google.com>
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A metaclass for custom Field subclasses. This ensures the model's attribute |
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parents:
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has the descriptor protocol attached to it. |
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Todd Larsen <tlarsen@google.com>
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""" |
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def __new__(cls, base, name, attrs): |
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new_class = super(SubfieldBase, cls).__new__(cls, base, name, attrs) |
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new_class.contribute_to_class = make_contrib( |
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attrs.get('contribute_to_class')) |
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return new_class |
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class Creator(object): |
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""" |
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A placeholder class that provides a way to set the attribute on the model. |
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""" |
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def __init__(self, field): |
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self.field = field |
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|
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def __get__(self, obj, type=None): |
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if obj is None: |
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raise AttributeError('Can only be accessed via an instance.') |
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return obj.__dict__[self.field.name] |
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|
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def __set__(self, obj, value): |
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obj.__dict__[self.field.name] = self.field.to_python(value) |
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|
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def make_contrib(func=None): |
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""" |
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Todd Larsen <tlarsen@google.com>
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Returns a suitable contribute_to_class() method for the Field subclass. |
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Todd Larsen <tlarsen@google.com>
parents:
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Todd Larsen <tlarsen@google.com>
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If 'func' is passed in, it is the existing contribute_to_class() method on |
03e267d67478
Major reorganization of the soc svn repo, to merge into a single App Engine
Todd Larsen <tlarsen@google.com>
parents:
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the subclass and it is called before anything else. It is assumed in this |
03e267d67478
Major reorganization of the soc svn repo, to merge into a single App Engine
Todd Larsen <tlarsen@google.com>
parents:
diff
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case that the existing contribute_to_class() calls all the necessary |
03e267d67478
Major reorganization of the soc svn repo, to merge into a single App Engine
Todd Larsen <tlarsen@google.com>
parents:
diff
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superclass methods. |
03e267d67478
Major reorganization of the soc svn repo, to merge into a single App Engine
Todd Larsen <tlarsen@google.com>
parents:
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""" |
03e267d67478
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Todd Larsen <tlarsen@google.com>
parents:
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def contribute_to_class(self, cls, name): |
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Todd Larsen <tlarsen@google.com>
parents:
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if func: |
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Todd Larsen <tlarsen@google.com>
parents:
diff
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func(self, cls, name) |
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Todd Larsen <tlarsen@google.com>
parents:
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else: |
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Todd Larsen <tlarsen@google.com>
parents:
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super(self.__class__, self).contribute_to_class(cls, name) |
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parents:
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setattr(cls, self.name, Creator(self)) |
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return contribute_to_class |