[Zope3-checkins] SVN: Zope3/branches/f12gsprint-widget/src/zope/ I
need to get back to some other things,
and don't want to leave this work
Gary Poster
gary at zope.com
Mon Oct 3 13:40:36 EDT 2005
Log message for revision 38721:
I need to get back to some other things, and don't want to leave this work
without being checked in at least. widget tests don't pass (but this is a
branch that I don't think anyone is following). Subview is the
current place where most of the work is being concentrated; will return to
widget later. Hope to return to this late this week or beginning of next.
Changed:
A Zope3/branches/f12gsprint-widget/src/zope/subview/
A Zope3/branches/f12gsprint-widget/src/zope/subview/README.txt
A Zope3/branches/f12gsprint-widget/src/zope/subview/__init__.py
A Zope3/branches/f12gsprint-widget/src/zope/subview/_subview.py
A Zope3/branches/f12gsprint-widget/src/zope/subview/draganddrop.txt
A Zope3/branches/f12gsprint-widget/src/zope/subview/i18n.py
A Zope3/branches/f12gsprint-widget/src/zope/subview/interfaces.py
U Zope3/branches/f12gsprint-widget/src/zope/widget/interfaces.py
U Zope3/branches/f12gsprint-widget/src/zope/widget/widget.py
U Zope3/branches/f12gsprint-widget/src/zope/widget/widget.txt
-=-
Added: Zope3/branches/f12gsprint-widget/src/zope/subview/README.txt
===================================================================
--- Zope3/branches/f12gsprint-widget/src/zope/subview/README.txt 2005-10-03 12:37:06 UTC (rev 38720)
+++ Zope3/branches/f12gsprint-widget/src/zope/subview/README.txt 2005-10-03 17:40:35 UTC (rev 38721)
@@ -0,0 +1,334 @@
+XXX The intent is to make this a test, as usual.
+
+===============
+Subview package
+===============
+
+The subview package provides a core set of interfaces for views that operate
+within other views, and some small base implementations.
+
+Views within other views include form widgets, JSR-168-type portlets, page
+composition portlets a la CPSskins, etc.
+
+This package is currently pertinent to browser views. It may be expanded to
+other types of subviews if we ever gain experience with them. It will need
+to be refactored at that time, if so.
+
+The goals of the core interface include the following.
+
+- Establish a standard pattern for subviews for easier interoperability.
+ Specifically, this package
+
+ * separates calculating subview state from rendering the subview; and
+
+ * defines the composition and use of prefixes.
+
+- Enable interoperable rich client-side approaches among subviews. In
+ particular, the package contemplates two common use cases:
+
+ * AJAX, so that client code from a rendered subview may directly address
+ the Python subview on the server for a given AJAX call; and
+
+ * drag and drop, so that unrelated subviews can allow items to be dragged
+ and dropped between them, and enabled via site configuration.
+
+- Enable subview persistence, so that subviews may be stashed away
+ temporarily and then redrawn. For instance,
+
+ * forms may need to defer to another form, perhaps adding a desired value to
+ a source used on the original form, before returning;
+
+ * wizards may simply persist views in a session as they gather information;
+
+ * form file widgets on persisted views may simply persist references to
+ gathered files as they validate and communicate with the user;
+
+ * one subview of many may be expanded, hiding all others, across
+ transactions; and then changed to a normal size again, revealing original
+ subviews;
+
+ * views may simply wish to persist, like portlets; and
+
+ * AJAX calls may benefit from interacting with persistent views.
+
+We will look at each of the three main features in turn: a standard pattern,
+rich-client support, and subview persistence.
+
+------------------
+A Standard Pattern
+------------------
+
+Based on lessons learned from the Zope 3 form code and from an in-house Zope
+Corporation JSR-168-like portlet system, the subview interfaces encapsulate
+current best practices. Some of these drive the other two main package goals,
+but two others bear highlighting.
+
+First, subviews often require an explicit delineation of
+initialization--calculating the state for the subview--and rendering.
+Following the pattern of the zope.formlib.interfaces.ISubPage interface, the
+subview interface separates this into update and render. All subviews should
+be updated before any are rendered. All analysis of the request and
+setting of subview state should happen in update, while all rendering (for the
+response) should happen in render. This is essential to supporting subviews
+that may affect other subviews: otherwise update bugs, in which the underlying
+data changed as expected but it was not drawn to screen because it was out of
+order, are frequent.
+
+For our examples, note that we are making no assumptions about the rendering
+output other than it being non-None.
+
+ >>> container = SubviewContainer()
+ >>> s = Subview()
+ >>> container._add('test', s) # !!! _add is not in API
+ >>> container.update() # this should also initialize the subview
+ >>> s.render() is not None # should output the subview rendering
+ True
+
+ >>> container = SubviewContainer()
+ >>> nested = NestedSubview()
+ >>> container._add('inter', nested) # !!! _add is not in API
+ >>> s = Subview()
+ >>> nested._add('test', s) # !!! _add is not in API
+ >>> container.update() # should cascade initialize down
+ >>> nested.render() is not None
+ True
+ >>> s.render() is not None
+ True
+
+Second, subviews have a prefix which, along with a final dot, is the namespace
+with which the subview should prefix all names and identifiers. The prefix
+may change between the update and render calls, which highlights another
+important aspect of parsing the request only in initialize:
+stored values should not rely on the current prefix.
+
+name is the name for this view in the subview container. parent is the
+immediate subview container of the subview. They are both only supposed to be
+accurate after update is called. The prefix of a subview is calculated by
+combining the prefix of the parent with a dot and the name of the subview.
+The prefix itself, as a name without a following dotted element, is reserved
+for use in the immediate subview container. The prefix of a subview container
+(that is not itself a subview) may be set directly.
+
+ >>> nested.parent is container
+ True
+ >>> s.parent is nested
+ True
+ >>> nested.name
+ 'inter'
+ >>> nested.prefix
+ 'inter'
+ >>> s.name
+ 'test'
+ >>> s.prefix
+ 'inter.test'
+ >>> container.prefix = 'cont'
+ >>> nested.prefix
+ 'cont.inter'
+ >>> s.prefix
+ 'cont.inter.test'
+ >>> nested.name = 'nest'
+ >>> nested.prefix
+ 'cont.nest'
+ >>> s.prefix
+ 'cont.nest.test'
+ >>> nested.render() is not None
+ True
+ >>> s.render() is not None
+ True
+
+To emphasize, the prefix should be used to calculate state during update,
+and to render during render; do not assume that the prefix will be the same
+across the calls. To reiterate, the prefix should be used as a namespace--a
+prefix--for identifiers within the subview, but the prefix itself, without a
+following '.', is reserved for use by the container, for a purpose described
+below.
+
+The fact that the prefix is calculated from the parent and the name, rather
+than set in toto, is another part of this best practice, different from
+previous interfaces. It reduces the chance for bugs when moving subviews
+among parents.
+
+ >>> s.prefix
+ 'cont.nest.test'
+ >>> s.parent = container
+ >>> s.parent is container
+ True
+ >>> s.prefix
+ 'cont.test'
+
+It's also worth noting that concurrency issues suggest that subview containers
+should be very wary of reassigning names, and particularly of reusing names
+for different subviews. For instance, imagine a subview container with two
+subviews. The programmer decides to name them with their order, '0' and '1'
+hypothetically. A first user looks at the page and begins to work with the
+second subview. Meanwhile, a second user deletes the first subview ('0'). If
+the names are simply based on order, then now what was subview '1' is subview
+'0'--if the first user tries to interact with the system, the rug will have
+been pulled out, because the subview appears to no longer exist. Further
+imagine that the second user added a completely new subview, now named '1'.
+If the first user submits now, then information intended for one subview will
+be sent to another.
+
+This hints at another problem: what should we do when the parent of the subview
+changes, in a similar story involving concurreny? This is a thornier problem
+for the applications that must address it. If your application must consider
+this problem, here are two possible solutions.
+
+- Use a calculated prefix for the object that is not based on hierarchy, as
+ described in ISubview.prefix.
+
+- Don't do it. Make a shallow static subview hierarchy and arrange subviews
+ using a different mechanism (a smarter main view, for instance).
+
+A separation between update and render and a prefix model are two important
+best practices used in the subview package. Other best practices are
+discussed in the remaining two sections.
+
+---------------------------
+Rich-Client Browser Support
+---------------------------
+
+As discussed in the introduction, this package contemplates support for two
+rich-client approaches in subviews: AJAX and drag and
+drop.
+
+AJAX
+----
+
+The primary AJAX use case is that a subview should be able to communicate
+directly with itself. This requires that there be a standard, agreed-upon way to
+address a subview via a URL. This package offers a traverser that uses a
+traversal namespace of ++subview++. It can be traversed with a subview's
+prefix, and will offer up registered names of the subview for following
+traversal. For instance, if a view is served at
+http://localhost/foo/index.html, and it has a nested subview with a prefix of
+bar.baz.bing, and it has a method named getWeather that it wants to address,
+then this might work:
+
+ def getWeather(self, location)...
+
+ >>> zcml("<configure><page name='getWeather' ...></configure>")
+ >>> browser.open(
+ ... 'http://localhost/foo/index.html/++subview++bar.baz.bing/getWeather?location=Fredericksburg')
+ >>> print browser.contents
+ 'The weather is lovely and cool right now.'
+
+This approach might also allow direct submission to a subview, if desired,
+which could return an html snippet to replace the subview. This would remove
+some of the necessity for our reliance on the super-form approach,
+which was developed to maintain state in the browser for multiple sub-forms
+when only one form was submitted.
+
+ XXX example
+
+Subview containers are required to make a div around the subview output with an
+id of the subview prefix and a class of 'zope.subview'. This div can be used
+to replace contents of the subview on the basis of the form submission, if
+desired. The div also has another use: an identifier for drag and drop,
+discussed next.
+
+Drag and Drop
+-------------
+
+Generic drag and drop between subviews can enable a number of very exciting
+scenarios. For instance, imagine a subview that provides a list of a user's
+most-used coworkers. Selecting the user in a form might involve dragging the
+coworker from one subview into a widget, that is itself a subview. Sending the
+user a message might involve dragging a document in one subview to a user in
+another. A complicated assembly process might be aided by a subview that
+maintained a clipboard, into which components could be dragged from multiple
+parts of the site while dragging, and out of which components could be dragged
+into assembly.
+
+If you find these stories exciting and compelling, this package establishes a
+tested and easy pattern that makes them possible. If you don't find them
+compelling, you'll be happy to know that opting out is trivial. The only
+shared requirement for all is that subview containers place a div around each
+subview's output with an id of the subview's prefix, and a class of
+'zope.subview'. If you are not interested in drag and drop, you can skip to
+the next section now ("Subview Persistence"). That's it.
+
+If you want to use drag and drop, see draganddrop.txt for more information.
+
+-------------------
+Subview Persistence
+-------------------
+
+As indicated in the introduction to this file, subview persistence has many
+use cases. The solution taken by the ISubview interface is simple, at least
+conceptually: make it implement standard ZODB persistence. If the object is
+not attached to a persistent object, it will be thrown away in normal garbage
+collection. If code wishes to persist the subview, simply attach it to a
+persistent data structure already part of the ZODB, such as a principal
+annotation.
+
+Unfortunately, the simple solution is not quite so simple in implementation.
+If a subview is persisted, it does have some unusual requirements. The
+majority of these are handled by the default base class.
+
+First, requests and non-IPersistent parents must not be persisted. The parent
+may not be persisted because it may be a transient view, not designed for
+persistence; the request is also not designed for persistence, and the next
+time the view is used it will probably need to be associated with the current
+request, not the original one. This constraint is met in the default base
+implementation by always getting the request from the interaction, instead of
+making it an actual attribute; and by storing non-persistent parents as
+request annotations.
+
+ >>> from zope.publisher.interfaces import IRequest
+ >>> IRequest.providedBy(Subview().request)
+ True
+ >>> from zope.persistent.interfaces import IPersistent
+ >>> IPersistent.providedBy(s)
+ True
+ >>> IPersistent.providedBy(nested)
+ True
+ >>> IPersistent.providedBy(container)
+ False
+ >>> nested.parent is container
+ True
+ >>> import cPickle
+ >>> getattr(cPickle.loads(cPickle.dumps(nested)), 'parent', None) is None
+ True
+ >>> s.parent = nested
+ >>> cPickle.loads(cPickle.dumps(s)).parent is nested
+ True
+ # XXX maybe do this with a real app, in a functional test wrapper...
+
+Second, when persisted subviews are used again, they must have the correct
+parent and request. The default implementation gets the request from the
+thread-local security interaction, so only re-updating the subview with the
+current parent should be necessary. The update method should be careful to
+accomodate new system state, rather than make assumptions. Note that a subview
+should always have 'update' called whenever it is used with a new request,
+before 'render' is called. Note that the default implementation also defers
+its context to the parent view, so that may not need to be reset.
+
+ # XXX end transaction, start a new one with a new request, and call update
+ # and render on 's'
+
+Last, if the subview is shared among various users, then essentially spurious
+but very annoying conflict errors may occur when parents (and requests, if the
+default implementation is not used) are tacked on to the subview. Each
+attribute assignment of 'parent' will tag the view as needing to be persisted,
+and thus cause the ZODB to raise a ConflictError if multiple users set the
+attribute--even though the attribute is not persisted! Persisted subviews
+sometimes store per-principal customization information in principal
+annotations; this approach might also be used to store the parent, but then
+again the value should not actually be persisted. The parent might also be
+stored in a request annotation: this might be the easiest approach, since the
+reference will naturally have the correct lifespan: this is taken by the
+default implementation. A third approach might be to write a __getstate__ that
+does not include parent or request along with conflict resolution
+code that ignores 'imaginary' changes like the ones to parent and request
+(as a reminder to the writer of this file :-), that's
+"def _p_resolveConflict(self, oldState, savedState, newState):...").
+
+ # make another DB copy of s, make a 'conflict' by setting parent, and
+ # show that transaction has no error. XXX
+
+It is essential for interoperability that subviews do not opt-out of the
+requirements for this part of the interface. Otherwise, their subviews will
+break intermediate persistent subviews in unpleasant ways (e.g., causing
+database exceptions when a transaction commits, etc.). Hopefully the shared
+base class will alleviate the annoyance for individual subview writers.
Property changes on: Zope3/branches/f12gsprint-widget/src/zope/subview/README.txt
___________________________________________________________________
Name: svn:keywords
+ Id
Name: svn:eol-style
+ native
Added: Zope3/branches/f12gsprint-widget/src/zope/subview/__init__.py
===================================================================
--- Zope3/branches/f12gsprint-widget/src/zope/subview/__init__.py 2005-10-03 12:37:06 UTC (rev 38720)
+++ Zope3/branches/f12gsprint-widget/src/zope/subview/__init__.py 2005-10-03 17:40:35 UTC (rev 38721)
@@ -0,0 +1,3 @@
+from _subview import (
+ SubviewBase, SubviewContainerBase, IntermediateSubviewMixin,
+ IntermediateSubview)
Property changes on: Zope3/branches/f12gsprint-widget/src/zope/subview/__init__.py
___________________________________________________________________
Name: svn:keywords
+ Id
Name: svn:eol-style
+ native
Added: Zope3/branches/f12gsprint-widget/src/zope/subview/_subview.py
===================================================================
--- Zope3/branches/f12gsprint-widget/src/zope/subview/_subview.py 2005-10-03 12:37:06 UTC (rev 38720)
+++ Zope3/branches/f12gsprint-widget/src/zope/subview/_subview.py 2005-10-03 17:40:35 UTC (rev 38721)
@@ -0,0 +1,146 @@
+##############################################################################
+#
+# Copyright (c) 2005 Zope Corporation and Contributors.
+# All Rights Reserved.
+#
+# This software is subject to the provisions of the Zope Public License,
+# Version 2.1 (ZPL). A copy of the ZPL should accompany this distribution.
+# THIS SOFTWARE IS PROVIDED "AS IS" AND ANY AND ALL EXPRESS OR IMPLIED
+# WARRANTIES ARE DISCLAIMED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+# WARRANTIES OF TITLE, MERCHANTABILITY, AGAINST INFRINGEMENT, AND FITNESS
+# FOR A PARTICULAR PURPOSE.
+#
+##############################################################################
+"""Subview helper implementations
+
+$Id$
+"""
+
+import persistent
+import persistent.dict
+import persistent.interfaces
+from zope import interface
+from zope.subview import interfaces
+import zope.security.management
+import zope.security.proxy
+from zope.publisher.interfaces import IRequest
+
+class SubviewBase(persistent.Persistent):
+ interface.implements(interfaces.ISubview)
+
+ context = request = name = parent = None
+
+ @property
+ def prefix(self):
+ if self.name is None or self.parent is None:
+ raise ValueError('name and parent must be set')
+ return '%s.%s' % (self.parent.prefix, self.name)
+
+ def render(self):
+ if not self._initialized:
+ raise RuntimeError('Initialize subview first')
+ # subclases should render now
+
+ _initialized=False
+ def update(self, parent=None, name=None):
+ self._initialized = True
+ if parent is not None:
+ self.parent = parent
+ if name is not None:
+ self.name = name
+ if self.parent is None or self.name is None:
+ raise RuntimeError(
+ "parent and name must be set or passed in to update")
+ # subclasses should calculate state now!
+
+def getRequest():
+ i = zope.security.management.getInteraction() # raises NoInteraction
+ for p in i.participations:
+ if IRequest.providedBy(p):
+ return p
+ raise RuntimeError('No IRequest in interaction')
+
+ANNOTATIONS_KEY = 'zope.subview'
+
+PersistentSubviewBase(persistent.Persistent, SubviewBase):
+
+ interface.implements(interfaces.IPersistentSubview)
+
+ @property
+ def context(self):
+ # avoid persisting possible security wrappers; avoid possible conflict
+ # errors
+ return self.parent.context
+
+ @property
+ def request(self):
+ # avoid persisting the request; avoid possible conflict errors
+ return getRequest()
+
+ _parent = None
+ @apply
+ def parent():
+ # we store persistent parents on this object, only changing when
+ # necessary so as not to invite conflict errors unnecessarily. we
+ # store non-persistent parents in the request, so that the parent
+ # is not persisted and so that we again do not invite conflict errors.
+ # we use id(self) because a request is not persistent: we are only
+ # stashing the id while the object is in memory, so we should be fine.
+ def get(self):
+ if self._parent is not None:
+ return self._parent
+ else:
+ parents = self.request.annotations.get(ANNOTATIONS_KEY)
+ if parents is not None:
+ return parents.get(id(self))
+ return None
+ def set(self, value):
+ # parent views should typically be unproxied, but just to be sure:
+ value = zope.security.proxy.removeSecurityProxy(value)
+ # if it is a persistent object...
+ if persistent.interfaces.IPersistent.providedBy(value):
+ # ...and we haven't stored it before (avoid conflict errors)
+ # then
+ if value is not self._parent:
+ self._parent = value
+ else:
+ if self._parent is not None: # avoid conflict errors
+ self._parent = None
+ parents = self.request.annotations.setdefault(
+ ANNOTATIONS_KEY, [])
+ parents[id(self)] = value
+ return property(get, set)
+
+class IntermediateSubviewMixin(object):
+
+ def getSubview(self, name):
+ raise NotImplementedError
+
+ def iterSubviews(self):
+ raise NotImplementedError
+
+ def update(parent=None, name=None):
+ super(IntermediateSubviewMixin, self).update(parent, name)
+ for key, val in self.iterSubviews:
+ val.update(self, key)
+
+ def getSubviewByPrefix(self, prefix):
+ # somewhat naive but probably sufficient implementation
+ if prefix == self.prefix:
+ return self
+ if (prefix.startswith(self.prefix) or
+ prefix.startswith('zope.subview.')):
+ for key, val in self.iterSubviews:
+ if interfaces.ISubviewContainer.providedBy(val):
+ res = val.getSubviewByPrefix(prefix)
+ if res is not None:
+ return res
+ elif val.prefix == prefix:
+ return res
+
+class IntermediateSubviewBase(IntermediateSubviewMixin, SubviewBase):
+ interface.implements(interfaces.IIntermediateSubview)
+
+class PersistentIntermediateSubviewBase(
+ IntermediateSubviewMixin, PersistentSubviewBase):
+ interface.implements(interfaces.IPersistentIntermediateSubview)
Property changes on: Zope3/branches/f12gsprint-widget/src/zope/subview/_subview.py
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Name: svn:keywords
+ Id
Name: svn:eol-style
+ native
Added: Zope3/branches/f12gsprint-widget/src/zope/subview/draganddrop.txt
===================================================================
--- Zope3/branches/f12gsprint-widget/src/zope/subview/draganddrop.txt 2005-10-03 12:37:06 UTC (rev 38720)
+++ Zope3/branches/f12gsprint-widget/src/zope/subview/draganddrop.txt 2005-10-03 17:40:35 UTC (rev 38721)
@@ -0,0 +1,31 @@
+=============
+Drag and Drop
+=============
+
+The pattern of the drag and drop approach is this.
+
+* First, on the browser, dragging and dropping an item needs to generate the id
+ of the dragged item, the id of the containing subview, the id of the drag
+ target, and the id of the containing subview. This means that draggable
+ items and targets need to be identified and given tokens that can be
+ resolved on the server back to the dragged item. The draggable items should
+ be identified with class="zope.subview.dnd_source"; the targets should be
+ identified with class="zope.subview.dnd_target". They should have ids that
+ are tokens that can be converted to the appropriate objects on the server,
+ as described below.
+
+* These four tokens--source object, target object, source subview, and target
+ subview--should be sent back to the server to determine what
+ the effect of the action is, if any. The call can be with AJAX or with a
+ full page submission.
+
+* The server should use ISubviewCollection.getSubviewByPrefix to get the subviews by their prefix (the
+ id on the page). They can then try to adapt the subviews to IDragAndDropSource
+ and IDragAndDropTarge, respectively. If adapters exist, then the object tokens
+ should be converted to objects. XXX otherwise no action
+
+* Get the multi adapter for (source object, target object, source subview,
+ target subview) to IDragAndDropHandler. XXX document return values; add
+ interfaces
+
+XXX
Property changes on: Zope3/branches/f12gsprint-widget/src/zope/subview/draganddrop.txt
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Name: svn:keywords
+ Id
Name: svn:eol-style
+ native
Added: Zope3/branches/f12gsprint-widget/src/zope/subview/i18n.py
===================================================================
--- Zope3/branches/f12gsprint-widget/src/zope/subview/i18n.py 2005-10-03 12:37:06 UTC (rev 38720)
+++ Zope3/branches/f12gsprint-widget/src/zope/subview/i18n.py 2005-10-03 17:40:35 UTC (rev 38721)
@@ -0,0 +1,32 @@
+##############################################################################
+#
+# Copyright (c) 2005 Zope Corporation. All Rights Reserved.
+#
+# This software is subject to the provisions of the Zope Visible Source
+# License, Version 1.0 (ZVSL). A copy of the ZVSL should accompany this
+# distribution.
+#
+# THIS SOFTWARE IS PROVIDED "AS IS" AND ANY AND ALL EXPRESS OR IMPLIED
+# WARRANTIES ARE DISCLAIMED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+# WARRANTIES OF TITLE, MERCHANTABILITY, AGAINST INFRINGEMENT, AND FITNESS
+# FOR A PARTICULAR PURPOSE
+#
+##############################################################################
+"""I18N support for subviews.
+
+This defines a `MessageFactory` for the I18N domain for the zope.subview
+package. This is normally used with this import::
+
+ from i18n import MessageFactory as _
+
+The factory is then used normally. Two examples::
+
+ text = _('some internationalized text')
+ text = _('helpful-descriptive-message-id', 'default text')
+"""
+__docformat__ = "reStructuredText"
+
+
+from zope import i18nmessageid
+
+MessageFactory = _ = i18nmessageid.MessageFactory("zope.subview")
Property changes on: Zope3/branches/f12gsprint-widget/src/zope/subview/i18n.py
___________________________________________________________________
Name: svn:keywords
+ Id
Name: svn:eol-style
+ native
Added: Zope3/branches/f12gsprint-widget/src/zope/subview/interfaces.py
===================================================================
--- Zope3/branches/f12gsprint-widget/src/zope/subview/interfaces.py 2005-10-03 12:37:06 UTC (rev 38720)
+++ Zope3/branches/f12gsprint-widget/src/zope/subview/interfaces.py 2005-10-03 17:40:35 UTC (rev 38721)
@@ -0,0 +1,182 @@
+##############################################################################
+#
+# Copyright (c) 2005 Zope Corporation and Contributors.
+# All Rights Reserved.
+#
+# This software is subject to the provisions of the Zope Public License,
+# Version 2.1 (ZPL). A copy of the ZPL should accompany this distribution.
+# THIS SOFTWARE IS PROVIDED "AS IS" AND ANY AND ALL EXPRESS OR IMPLIED
+# WARRANTIES ARE DISCLAIMED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+# WARRANTIES OF TITLE, MERCHANTABILITY, AGAINST INFRINGEMENT, AND FITNESS
+# FOR A PARTICULAR PURPOSE.
+#
+##############################################################################
+"""Subview interfaces
+
+$Id$
+"""
+
+from zope.component.interfaces import IView
+from zope import interface, schema
+from zope.subview.i18n import _
+
+# XXX try to reconcile with zope.formlib.interfaces.ISubPage: I hope to
+# remove setPrefix from that interface, and ideally add parent and name,
+# to that interface. That will take discussion. If that happens, then
+# I'd like to try to import ISubPage and declare ISubview to extend ISubPage
+# if the formlib package exists.
+
+class IPrefixedView(IView):
+
+ prefix = schema.DottedName(
+ title=_('Prefix'), description=_(
+ """A prefix for view ids, uniquely identifying the element among the
+ view and any of its contained subviews. The view must not use the
+ prefix directly for any names or ids: it is reserved by containing/calling
+ views, if any. The prefix should be used with a following dot ('.')
+ for all identifiers within the view--that is, if a prefix is 'form',
+ then names and ids within the associated view should all begin with
+ 'form.', like 'form.title'.""",
+ readonly=True, required=True)
+
+class ISubview(IPrefixedView):
+ """A view that does not render a full page, but part of a page."""
+
+ def render():
+ """render subview; should (but not required) raise error if called
+ before update
+
+ (see update)"""
+
+ def update(parent=None, name=None):
+ """Initialize subview: perform all state calculation here, not in render).
+
+ Initialize must be called before any other method that mutates the
+ instance (besides __init__). Non mutating methods and attributes may
+ raise an error if used before calling update. Subview may rely on
+ this order but are not required to explicitly enforce this.
+ Implementations may enforce it as a developer aid.
+
+ parent and name must be set before this method is called, or
+ they must be passed in (as the parent and name arguments,
+ respectively) and set initially by this method. See the attributes for
+ more detail. parent and name may be set independently of this method,
+ such as between update and render, if state calculation should
+ be performed in one context, and rendering in another.
+
+ The subview will try to get its state from the environment (e.g., the
+ context and request), using the prefix, if any. The state will be used
+ to try to reinitialize the subview's user-visible state.
+
+ In order to facilitate non-stateless interactions, update
+ must be able to be called more than once on the same subview instance.
+ Each call should recalculate the subview state on the basis of the new
+ arguments.
+
+ If this subview is a subview container, it is responsible for calling
+ update on all directly contained subviews when update is
+ called (*not* postponed to render).
+ """
+
+ parent = interface.Attribute(
+ """The ISubviewCollection that contains this view. Required.""")
+
+ name = schema.DottedName(
+ title=_('Name'), description=_(
+ """The name by which this subview may be obtained from its __parent__
+ via getSubview. Subviews may suggest values but must be amenable
+ to having the suggestions overridden. Suggested values, if any, must
+ be stable across renderings and transactions.
+
+ Concurrency issues suggest that you should often avoid reusing subview
+ names (that is, having names refer to one subview and then another)
+ within a given logical set of renderings of a subview.
+ """),
+ min_dots=0, max_dots=0, required=True)
+
+ prefix = schema.DottedName(
+ title=_('Prefix'), description=_(
+ """See IPrefixedView.prefix. Must be calculated. Prefix must be one
+ of two types.
+
+ One choice is a hierarchically derived combination of the parent's
+ prefix value joined by a dot ('.') to the name. For instance, if the
+ parent's prefix were 'left_slot.form' and the current name were
+ 'title', then the prefix would be 'left_slot.form.title'.
+
+ The other choice is a guaranteed unique and consistent name, as
+ determined by the subview author, following a prescribed formula: the
+ reserved initial prefix of 'zope.subview.', plus the path to the
+ package of the code that is providing the unique ids, plus the unique
+ id. For instance, if someone used the intid utility to provide unique
+ names, and the intid of the current view were 13576, the prefix might
+ be 'zope.subview.zope.app.intid.13576'. Note that this subview might
+ itself be a parent to another subview that got its prefix via the
+ hierarchical combination; if its name were 'title' then its prefix
+ would be zope.subview.zope.app.intid.13576.title""", readonly=True,
+ required=True)
+
+class IPersistentSubview(ISubview):
+ """Must also implement IPersistent. However, requests, contexts, and
+ non-IPersistent parents *must not be persisted*. (Requests and security
+ wrappers around contexts are not persistable, and non-persistent parents
+ are not designed to be persistent and so may themselves contain references
+ to requests, contexts, or other problematic values.)"""
+
+class ISubviewCollection(IPrefixedView):
+ """Collection of subviews, geared towards iterating over subviews and
+ finding specific subviews by name.
+
+ To enable replacement of individual subviews on a page through technologies
+ such as AJAX, and to enable drag and drop approaches within subviews,
+ subview collections must enclose the rendered output of each
+ directly contained subview within a div block with an id of the subview's
+ prefix and a class of "zope.subview".
+ """
+
+ def iterSubviews():
+ """return an iterator of pairs of (name, subview) for all directly
+ contained subviews."""
+
+ def getSubview(name):
+ """given a name, return the directly contained subview, or None if not
+ found."""
+
+ def getSubviewByPrefix(prefix):
+ """return the (nested) subview matching the given prefix, or None.
+ """
+
+ prefix = schema.DottedName(
+ title=_('Prefix'), description=_(
+ """See IPrefixedView.prefix. If this is not also an ISubview,
+ then this value is writable.""", readonly=False, required=True)
+
+ def update():
+ """Initialize all contained subviews: perform all state calculation.
+ """
+
+class IPersistentSubviewCollection(ISubviewCollection):
+ """Implements IPersistent. However, requests and contexts *must not be
+ persisted*. (Requests and security wrappers around contexts are not
+ persistable.)
+
+ Any contained subview must implement IPersistentSubview (including
+ IPersistentIntermediateSubview, which extends IPersistentSubview).
+ """
+
+class IIntermediateSubview(ISubview, ISubviewCollection):
+ """A subview that may contain nested subviews. Note that prefix is
+ readonly, like ISubview and IPrefixedView, but different from
+ ISubviewCollection"""
+
+class IPersistentIntermediateSubview(
+ IPersistentSubview, IPersistentSubviewCollection, IIntermediateSubview):
+ """Implements IPersistent. However, requests, contexts, and
+ non-IPersistent parents *must not be persisted*. (Requests and security
+ wrappers around contexts are not persistable, and non-persistent parents
+ are not designed to be persistent and so may themselves contain references
+ to requests, contexts, or other problematic values.)
+
+ Any contained subview must implement IPersistentSubview (including
+ IPersistentIntermediateSubview, which extends IPersistentSubview).
+ """
Property changes on: Zope3/branches/f12gsprint-widget/src/zope/subview/interfaces.py
___________________________________________________________________
Name: svn:keywords
+ Id
Name: svn:eol-style
+ native
Modified: Zope3/branches/f12gsprint-widget/src/zope/widget/interfaces.py
===================================================================
--- Zope3/branches/f12gsprint-widget/src/zope/widget/interfaces.py 2005-10-03 12:37:06 UTC (rev 38720)
+++ Zope3/branches/f12gsprint-widget/src/zope/widget/interfaces.py 2005-10-03 17:40:35 UTC (rev 38721)
@@ -18,7 +18,7 @@
__docformat__ = 'restructuredtext'
from zope.schema.interfaces import ValidationError
-from zope.component.interfaces import IView
+import zope.subview.interfaces
from zope.interface import Attribute, Interface, implements
from zope.schema import Bool
@@ -28,21 +28,14 @@
class ConversionError(ValueError):
""" Value could not be converted to correct type """
-
-class InvalidStateError(RuntimeError):
- """ This widget's state has been invalidated by a call to setValue()"""
-class IWidget(IView):
+class IWidget(zope.subview.interfaces.ISubview):
"""Generically describes the behavior of a widget.
-
- This must be presentation independent.
+
+ Note that all state calculation (e.g., gathering value from request) must
+ happen within initialize.
"""
- name = Attribute(
- """The unique widget name
-
- This must be unique within a set of widgets.""")
-
label = Attribute(
"""The widget label.
@@ -64,12 +57,6 @@
field can be set to False for widgets that always provide input (e.g.
a checkbox) to avoid unnecessary 'required' UI notations.
""")
-
- prefix = Attribute("""Element names should begin with the given `prefix`.
- Prefix name may be None, or a string. Any other value raises
- ValueError. When prefixes are concatenated with the widget name, a dot
- is used as a delimiter; a trailing dot is neither required nor suggested
- in the prefix itself. """)
error = Attribute(""" An exception created by initialize or setValue. If
this value is not None, it is raised when getValue is called.
@@ -81,60 +68,45 @@
setValue. Minimally, a message object is expected to be adaptable to
a view named snippet.
""")
-
- def __call__():
- """ render widget """
- def initialize(prefix=None, value=marker, state=None):
- """ Initialize widget and set its value.
-
- Initialize must be called before any other method besides __init__.
-
- If prefix is passed in, the prefix attribute of the widget is set.
- Prefix must be None or be a string. See prefix attribute for more
- detail.
-
- If neither value nor state is included, the widget will try
- to set its value from the request.
-
- If value is passed in, the widget will use that value. If state is
- passed in, the widget will use the state object to set its value and
- do any other initialization desired. The state object must be obtained
- from the getState method of a widget of the same class.
-
- Only one of value or state may be passed, passing both raises
- TypeError.
-
- If the widget's value is not valid, its error attribute will contain
- either a ConversionError or zope.schema.interfaces.ValidationError. If
- a widget wishes to add an object to message, that may be done here.
- """
-
- def getState():
- """ If the widget has been viewed previously, returns a non-None,
- picklable object representing the widget's state, unless setValue has
- been called, in which case it raises InvalidStateError. Otherwise,
- returns None.
-
- A state object can later be passed in to initialize to restore the
- state of the widget.
+ def hasInput():
+ """True if subview has a user-visible (client-side) state from a
+ previous rendering (either persistently or from the most recent
+ initialization).
"""
- def hasState():
- """ Return True if the widget has a state from a previous request.
+ def update(parent=None, name=None, value=marker):
+ """ Initialize widget, calculating all state; and set its value.
- Should be equivalent to self.getState() is not None.
- """
+ See ISubview.initialize for essential basic behavior.
+ If the value is not provided, it will try to calculate the value from
+ the environment (e.g., the a browser request).
+
+ After a call to initialize, if the widget's value is not valid, its
+ error attribute will contain either a ConversionError or
+ zope.schema.interfaces.ValidationError. If a widget wishes to add an
+ object to message, that may be done here."""
+
def getValue():
""" Return the current value as set by initialize or setValue.
- If error is not None, raise it."""
+ Value is *not* validated. Value should not be used to assign to
+ a field unless the widget's error attribute is None.
+ May raise ConversionError (i.e., widget has state but does not
+ know how to convert it to a validatable value) but not
+ ValidationError. For instance, if the widget's value is currently a
+ required field's missing value, getValue must return the missing value.
+
+ If setValue was called and did not raise an exception, the value
+ must be returnable by this method."""
+
def setValue(value):
""" Sets the current value of the widget. Resets the error and
message attributes to only the message and error pertaining
- to the new value, if any.
+ to the new value, if any. Must minimally accept the widget's field's
+ missing value and valid values.
"""
class IInputWidget(IWidget):
@@ -143,3 +115,57 @@
class IDisplayWidget(IWidget):
"""a widget used for display"""
+class IBrowserInputWidget(IWidget):
+ """a browser widget used for input"""
+
+class IBrowserDisplayWidget(IWidget):
+ """a browser widget used for display"""
+
+class ICoreWidget(interface.Interface):
+ """A private interface to support lean widgets usable in both the old and
+ new widget frameworks.
+
+ The interface intends to allow for full flexibility by the widget author,
+ while enforcing the patterns needed by the subview and widget interfaces.
+ The only particularly unusual approach is using a state object to pass
+ calculated values. This state should not depend on the widget's name or
+ prefix for use. It encourages all state calculation to be done once,
+ as is necessary for the initialize method.
+ """
+
+ def renderInvalidValue(context, request, name, value):
+ """render a widget for an invalid value; typically renders a widget
+ with an empty value.
+
+ This is only called if calculateState returned None, or if
+ a value has been explicitly set on the widget; and the value is
+ invalid, according to the widget's field (context)."""
+
+ def renderValidValue(context, request, name, value):
+ """render a widget for the given valid value
+
+ This is only called if calculateState returned None, or if
+ a value has been explicitly set on the widget; and the value is
+ valid, according to the widget's field (context)."""
+
+ def renderState(context, request, name, state):
+ """render a widget for the given valid (non-None) state.
+
+ This is called if calculateState returned a non-None value and the
+ widget's value was not set explicitly.
+ """
+
+ def calculateState(context, request, name):
+ """return the widget's state object if the (logical) widget was
+ rendered previously, or None.
+
+ State must be persistable."""
+
+ def calculateValue(state):
+ """given a state provided by calculateState, return a value, or raise
+ ConversionError"""
+
+ def needsRedraw(context, request, state):
+ """return a boolean on whether the given state (provided by
+ calculateState) suggests that the widget should be redrawn (for
+ instance, because the widget processed an internal submit)."""
Modified: Zope3/branches/f12gsprint-widget/src/zope/widget/widget.py
===================================================================
--- Zope3/branches/f12gsprint-widget/src/zope/widget/widget.py 2005-10-03 12:37:06 UTC (rev 38720)
+++ Zope3/branches/f12gsprint-widget/src/zope/widget/widget.py 2005-10-03 17:40:35 UTC (rev 38721)
@@ -14,74 +14,60 @@
$Id: form.py 38007 2005-08-19 17:50:28Z poster $
"""
+import persistent
+import persistent.dict
from zope import interface
+import zope.subview
from zope.app.pagetemplate.viewpagetemplatefile import ViewPageTemplateFile
-from zope.schema.interfaces import ValidationError
+from zope.schema.interfaces import ValidationError, RequiredMissing
from xml.sax.saxutils import quoteattr
from zope.widget import interfaces
-class BaseInputWidget(object):
- """base simple widget"""
+class Widget(zope.subview.SubviewBase):
+ """widget, designed to be used by composition or subclass to get core
+ behavior"""
- interface.implements(interfaces.IInputWidget)
+ interface.implements(interfaces.IWidget)
__doc__ = interfaces.IInputWidget.__doc__
- _name = None
- name = property(lambda self: self._name)
-
- _prefix = None
- def prefix(self, value):
- self._prefix = value
- if value is None:
- self._name = self.context.__name__
- else:
- self._name = '.'.join((value, self.context.__name__))
- prefix = property(lambda self: self._prefix, prefix)
-
_error = None
error = property(lambda self: self._error)
_message = None
message = property(lambda self: self._message)
- def __init__(self, context, request):
+ def __init__(self, context, request, core_widget=None):
self.context = context
self.request = request
self.label = context.title
self.hint = context.description
self.required = context.required
-
+ assert core_widget is None or interfaces.ICoreWidget.providedBy(
+ core_widget)
+ self._core_widget = core_widget
+
_valueForced = False
- _initialized = False
- _state = None
- def initialize(self, prefix=None, value=interfaces.marker, state=None):
- self._initialized = True
- self.prefix = prefix
- if state is None:
- state = self._calculateStateFromRequest()
- else:
- if value is not interfaces.marker:
- raise TypeError('May pass only one of value and state')
- self._state = state
+ def update(self, parent=None, name=None, value=interfaces.marker):
+ super(Widget, self).initialize(parent, name)
+ self._state = self._calculateState()
if value is interfaces.marker:
- if self._state is None:
- value = self.context.default
+ if not self.hasInput():
+ self.setValue(self.context.default) # effectively a force
else:
- value = self._calculateValueFromState()
- self.setValue(value)
- self._valueForced = False
+ try:
+ value = self._calculateValue()
+ except interfaces.ConversionError, e:
+ self._error = e
+ self._message = None
+ self._value = self.context.missing_value
+ else:
+ self.setValue(value)
+ self._valueForced = False # not a force
else:
- self.setValue(value)
-
- def getState(self):
- if not self._initialized:
- raise RuntimeError('Initialize widget first')
- if self._state is not None and self._valueForced:
- raise interfaces.InvalidStateError()
- return self._state
+ self.setValue(value) # this is a force.
- def hasState(self):
+ def hasInput(self):
if not self._initialized:
raise RuntimeError('Initialize widget first')
return self._state is not None
@@ -90,7 +76,8 @@
def getValue(self):
if not self._initialized:
raise RuntimeError('Initialize widget first')
- if self.error is not None:
+ if self.error is not None and isinstance(
+ self.error, interfaces.ConversionError):
raise self.error
return self._value
@@ -107,55 +94,127 @@
self._value = value
self._valueForced = True
- def __call__(self):
+ # the following methods may typically either be overridden or be used
+ # as is, delegating to an ICoreWidget implementation.
+
+ def needsRedraw(self):
+ return self._valueForced or (
+ self._state is not None and self._core_widget.needsRedraw(
+ self.context, self.request, self._state))
+ needsRedraw = property(needsRedraw)
+
+ def render(self):
+ """render the widget.
+
+ if self._valueForced:
+ if self.error is not None:
+ draw the widget with no value filled in
+ else:
+ draw the widget on the basis of the current value
+ else:
+ draw the widget on the basis of the _state (which should
+ always be non-None if _valueForced is False)"""
+ if self._valueForced:
+ if self.error is not None:
+ return self._core_widget.renderInvalidValue(
+ self.context, self.request, self.prefix, self._value)
+ else:
+ return self._core_widget.renderValidValue(
+ self.context, self.request, self.prefix, self._value)
+ else:
+ return self._core_widget.renderState(
+ self.context, self.request, self.prefix, self._state)
+
+ def _calculateState(self):
+ """return the widget's state object if the (logical) widget was
+ rendered previously, or None."""
+ return self._core_widget.calculateState(
+ self.context, self.request, self.name)
+
+ def _calculateValue(self):
+ """return the current value only on the basis of the _state attribute.
+
+ Do not validate. If cannot generate a value from the current _state,
+ raise zope.widget.interfaces.ConversionError.
+
+ _state will never be None when this method is called."""
+ return self._core_widget.calculateValue(self._state)
+
+class CoreWidget(persistent.Persistent):
+
+ interface.implements(interfaces.ICoreWidget)
+
+ def renderInvalidValue(self, context, request, name, value):
+ """render a widget for an invalid value"""
raise NotImplementedError
+
+ def renderValidValue(self, context, request, name, value):
+ """render a widget for the given valid value"""
+ raise NotImplementedError
+
+ def renderState(self, context, request, name, state):
+ """render a widget for the given state"""
+ raise NotImplementedError
+
+ def calculateState(self, context, request, name):
+ """return the widget's state object if the (logical) widget was
+ rendered previously, or None.
- def _calculateStateFromRequest(self):
- """return the widget's state object if it was rendered previously, or
- None"""
- return self.request.form.get(self.name)
+ This simple implementation is good for widgets that have only one
+ input field."""
+ return request.form.get(name+".value")
- def _calculateValueFromState(self):
- """return the current value on the basis of the _state attribute"""
+ def calculateValue(self, state):
+ """given a state, return a value, or raise ConversionError"""
raise NotImplementedError
-
-class AdvancedBaseInputWidget(BaseInputWidget):
+ def needsRedraw(self, context, request, state):
+ return False
+
+class AdvancedCoreWidget(object):
"""base advanced widget"""
- def _calculateStateFromRequest(self):
- res = {}
- name = self.name
- len_name = len(name)
- prename = name + "."
- for n, v in self.request.form.items():
- if n == name or n.startswith(prename):
- res[n[len_name:]] = v
+ def calculateState(self, context, request, name):
+ """return the widget's state object if the (logical) widget was
+ rendered previously, or None.
+
+ This advanced implementation is good for widgets that are comprised
+ of multiple input fields. It means that the state object (if not None)
+ is a dictionary."""
+ res = persistent.dict.PersistentDict()
+ prefix = self.prefix + "."
+ slice = len(prefix)
+ for n, v in request.form.items():
+ if n.startswith(prefix):
+ res[n[slice:]] = v
return res or None
-class TextLineWidget(BaseInputWidget):
-
- #template = namedtemplate.NamedTemplate('default')
-
- t = ("""<input type="text" value=%(value)s name=%(name)s """
- """id=%(name)s size="20" />""")
-
+class CoreTextLineWidget(SimpleCoreWidget):
- def __call__(self):
- if self._valueForced:
- value = self.getValue()
- else:
- value = self._state
- return self.t % {'value':quoteattr(value or ''),
- 'name':quoteattr(self.name)}
+ def __init__(self, size='20', extra=''):
+ self.size = size
+ self.extra = extra
- #("""<input type="text" value=%(value)s name=%(name)s """
- # """id=%(name)s size="20" />""")
-
- def _calculateValueFromState(self):
+ def renderInvalidValue(self, context, request, name, value):
+ return self.renderValidValue(name, '')
+
+ def renderValidValue(self, context, request, name, value):
+ return (
+ """<input type="text" value=%(value)s name=%(name)s """
+ """id=%(name)s size="%(size)s" %(extra)s />""" %
+ {'value': value, 'name': name+".value", 'size': self.size,
+ 'extra': self.extra})
+ renderState = renderValidValue
+
+ def calculateValue(self, state):
try:
- value = unicode(self._state)
- except ValueError, v: # XXX
- e = interfaces.ConversionError(v)
- else:
- return value
+ return unicode(state)
+ except ValueError, v:
+ raise interfaces.ConversionError(v)
+
+textLineWidget = CoreTextLineWidget()
+
+def TextLineWidget(context, request):
+ w = InputWidget(context, request, textLineWidget)
+ interface.directlyProvides(w, interfaces.IBrowserInputWidget)
+ return w
Modified: Zope3/branches/f12gsprint-widget/src/zope/widget/widget.txt
===================================================================
--- Zope3/branches/f12gsprint-widget/src/zope/widget/widget.txt 2005-10-03 12:37:06 UTC (rev 38720)
+++ Zope3/branches/f12gsprint-widget/src/zope/widget/widget.txt 2005-10-03 17:40:35 UTC (rev 38721)
@@ -1,18 +1,51 @@
-=====
+==========
Widget API
-=====
+==========
+Widgets are views on schema fields--that is, components that adapt a schema
+field and a request, and provide methods that are intended to generate user
+interface code. The user interface is either designed to gather input from
+a user or to display values to a user. Widgets must be assembled and displayed
+by a coordinating component such as a zope.formlib form.
+The widget package has three clients:
+
+- developers who want to use widgets to gather information from end users;
+- developers who want to create widgets; and
+- the end users themselves.
+
+This document addresses the first two clients. We will first examine the full
+widget API, trying to provide a guide for developers who want to use widgets.
+We will then
+for
+The widget API is a simple approach based on the concept of calculating and
+processing user-visible state objects. The widget module provides some simple
+abstract classes that should let most widget writers concentrate on only two
+tasks: rendering the widget, a
+
>>> from zope.widget import widget, interfaces
-
>>> from zope.publisher.browser import TestRequest
>>> from zope.schema import TextLine
>>> request = TestRequest()
+ >>> context = object()
+
+Field is required but has no default
+
>>> field = TextLine(__name__='test_name', title=u'Test Title',
... min_length=2, description=u'Test Description')
- >>> context = object()
>>> field = field.bind(context)
+
+Field2 is required and has a default value.
+
+ >>> field2 = TextLine(__name__='test_name', title=u'Test Title',
+ ... min_length=2, description=u'Test Description',
+ ... default=u'test_default')
+ >>> field2 = field2.bind(context)
+
+Create the widget.
+
>>> w = widget.TextLineWidget(field, request)
+
After creating a widget, the next step that must be taken is to initialize it.
@@ -42,7 +75,17 @@
Traceback (most recent call last):
...
RequiredMissing
+
+A widget with a required field with a default value, will obtain that default.
+ >>> request = TestRequest()
+ >>> w = widget.TextLineWidget(field2, request)
+ >>> w.initialize()
+ >>> w.getValue()
+ u'test_default'
+
+
+
If the previous request rendered the field, the state will be gathered from it
during initialize; if value is not passed explicitly to initialize, it will
be set from the gathered state.
@@ -118,6 +161,24 @@
False
>>> w.getState() # None
+
+It is possible to explicitly set the value to None rather than accept the
+default value.
+
+ >>> request = TestRequest()
+ >>> w = widget.TextLineWidget(field2, request)
+ >>> w.initialize(value=None)
+ >>> w.getValue() # None
+
+ >>> request = TestRequest()
+ >>> w = widget.TextLineWidget(field2, request)
+ >>> w.initialize() # will use field default value
+ >>> w.getValue()
+ 'test_default'
+ >>> w.setValue(None)
+ >>> w.getValue() # None
+
+
State objects are black boxes. The only contract they have is that they are
pickleable. Do not rely on their values, except for their intended use.
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