newforms: Split the Form class into BaseForm and Form. The former has all the Form logic; the latter just implements the metaclass that allows for declarative form definition. This change makes it easier to allow other (i.e., non-declarative) designation of a form's fields in creating a form class

git-svn-id: http://code.djangoproject.com/svn/django/trunk@4204 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/newforms/forms.py

@@ -32,10 +32,11 @@ class DeclarativeFieldsMetaclass(type):
         attrs['fields'] = SortedDictFromList(fields)
         return type.__new__(cls, name, bases, attrs)
 
-class Form(StrAndUnicode):
-    "A collection of Fields, plus their associated data."
-    __metaclass__ = DeclarativeFieldsMetaclass
-
+class BaseForm(StrAndUnicode):
+    # This is the main implementation of all the Form logic. Note that this
+    # class is different than Form. See the comments by the Form class for more
+    # information. Any improvements to the form API should be made to *this*
+    # class, not to the Form class.
     def __init__(self, data=None, auto_id='id_%s', prefix=None):
         self.ignore_errors = data is None
         self.data = data or {}
@@ -168,6 +169,15 @@ class Form(StrAndUnicode):
         """
         return self.clean_data
 
+class Form(BaseForm):
+    "A collection of Fields, plus their associated data."
+    # This is a separate class from BaseForm in order to abstract the way
+    # self.fields is specified. This class (Form) is the one that does the
+    # fancy metaclass stuff purely for the semantic sugar -- it allows one
+    # to define a form using declarative syntax.
+    # BaseForm itself has no way of designating self.fields.
+    __metaclass__ = DeclarativeFieldsMetaclass
+
 class BoundField(StrAndUnicode):
     "A Field plus data"
     def __init__(self, form, field, name):