ANN: Nevow 0.3 released

Valentino Volonghi aka Dialtone dialton3#NOSPAM.JJJJKIKK at
Mon Sep 27 18:17:05 CEST 2004

GET it here:

More Informations:

Nevow (pronounced nou-veau) is a web application construction kit written
in Python. It is designed to allow the programmer to express as much of
the view logic as desired in Python, and includes a pure Python XML
expression syntax named stan to facilitate this. However it also provides
rich support for designer-edited templates, using a very small XML
attribute language to provide bi-directional template manipulation

Nevow also includes formless, a declarative syntax for specifying the
types of method parameters and exposing these methods to the web. Forms
can be rendered automatically, and form posts will be validated and input
coerced, rendering error pages if appropriate. Once a form post has
validated successfully, the method will be called with the coerced values.

Finally, Nevow includes LivePage, a two-way bridge between JavaScript in
a browser and Python on the server. For 0.3, LivePage has been updated to
operate on Mozilla, Firefox, Windows Internet Explorer 6, and Safari on
Mac OS X. Event handlers can be written in pure Python and JavaScript
implementation details are hidden from the programmer, with Nevow taking
care of routing data to and from the server using XmlHttpRequest.

    * XHTML templates: contain no programming logic, only nodes tagged
    with nevow attributes 
    * data/render methods: simplify the task of separating data from
    presentation and writing view logic 
    * stan: An s-expression-like syntax for expressing xml in pure python
    * formless: For describing the types of objects which may be passed to
    methods of your classes, validating and coercing string input from
    either web or command-line sources, and calling your methods
    automatically once validation passes 
    * webform: For rendering web forms based on formless type
    descriptions, accepting form posts and passing them to formless
    validators, and rendering error forms in the event validation fails     
    * livepage: Cross-browser JavaScript glue for sending client side
    events to the server and server side events to the client after the
    page has loaded, without causing the entire page to refresh

Bug Tracker:
IRC:  irc://


What's New in Nevow 0.3:

2004-09-26	Donovan Preston <dp at>

	* Added nevow.inevow.IQ interface, an interface for querying the
	stan DOM. Eventually, this interface will contain APIs for doing
	traditional DOM introspection, such as iterating children,
	examining tag names, and examining attributes. For now, it contains
	only the patternGenerator, onePattern, and allPatterns APIs. These
	APIs have been deprecated from Context.

	The main benefit of this is the ability to do:


	which would be nice for creating "pattern library" files containing
	common skin idioms which can then be copied and used throughout
	the app.

2004-09-25	Donovan Preston <dp at>

	* Chatola received a major facelift, bringing it from cool demo
	up to almost a full fledged web-based chat server. The helper API was added, which deprecates 

2004-09-23	Tommi Virtanen	<tv at>

	* Make guard.SessionWrapper store its URL  location in all requests it
	passes to its children. This allows the children know where to post
	the __login__ and __logout__ forms, even deep inside the resource
	tree (fixes issue59).

	* Guard now works as a non-root resource, with help from the above
	change. Semantics of __login__ clarified in unit tests; if your guard
	is at /foo, posting to /foo/__login__ redirects to /foo, and posting
	to /foo/__login__/ redirects to /foo/. The two unit tests that failed
	earlier now pass (with that change in their __login__ URLs).

	* If URL-based sessions are used, login no longer loses session
	information due to redirect to / (fixes issue56).

2004-09-20	Matt Goodall <matt at>

	* Added method to make switching between http and 
	https easier.

2004-09-08	Donovan Preston	<dp at>

	* Nevow now includes a very simple proof-of-concept WSGI Application 
	implementation, and can be used with no Twisted dependency. Nevow can 
	also be used to write CGIs, either using a simple CGI WSGI gateway 
	(which supports URL traversal), or by using Page.renderString (which does not).

	* Two new context interfaces, ICurrentSegments and IRemainingSegments, 
	replace the need to examine the Request prepath and postpath attributes

	* ISerializable is deprecated, and has been replaced with a simple 
	Flattener registry. nevow.flat.registerFlattener and 
	nevow.flat.getFlattener have been added to support this.

2004-09-06	Donovan Preston	<dp at>

	* BACKWARDS INCOMPATIBLE CHANGE. Page.configurable_ *always* returns
	self, and a new Page.configurable_original *always* returns
	self.original. If you were relying on Page.configurable_'s
	introspection behavior and are now getting errors about adapting
	to IConfigurable, change your renderForms() calls to:


	This causes Page.configurable_original to be invoked and
	introspected for form rendering.

2004-08-23	Donovan Preston <dp at>

	* LivePage uses a simpler implementation strategy which requires
	the browser to make one request per output event. As a result,
	LivePage now works on Mozilla, Safari, and Internet Explorer Windows.

2004-08-05	Donovan Preston <dp at>

	* Implemented support for IFoo(ctx) synonym syntax. It does the
	same thing as ctx.locate(IFoo)

	* Removed Resource Generators, a feature of NevowSite that nobody
	used and wasn't really useful.

	* Changed all inevow.IResource apis to take a Context object
	where they used to take the request. Remembering objects in
	PageContexts is now much easier, and fewer hacks are required to
	build the context chain. The context chain now looks like:


2004-7-28	Donovan Preston <dp at>

	* Parameterize data_* methods in the same way as render_* methods.
	Patch by k3mper.

	For example, <div nevow:data="foo bar,baz" /> will cause 
	data_foo(self, bar, baz) to be called with the strings "bar" and
	"baz". This data method should return a callable taking ctx, data.
	The return value of this callable will be remembered as IData at
	this point in the context stack.

	* Added list-slicing support to ListContainer. You may now use
	list slicing syntax in a data directive in addition to a simple
	index. For example:

	def data_aList(self, ctx, data):
		return ["Buckle", "My", "Shoe"]

	<div nevow:data="aList">
		<span nevow:data="1:-1" nevow:render="string" />

	Will render as <div><span>My</span></div>

2004-7-20	Matt Goodall <matt at>

	* Modified sax loader to retain doctypes, comments and xmlns attributes. 
	It's now possible to build XHTML valid pages :).

	xmlns attributes are always kept but there are options to ignore the doctype
	and comment (at the request of foom, not sure why yet). Right now, the default
	is to retain doctypes and comments but you can use the ignoreDocType and
	ignoreComment args to the xml loaders and flatsax parse functions. This bit
	may change.

	* Add a URL -> IResource adapter that performs a HTTP redirect. URLs can then
	be returned from locateChild().

2004-06-07	Donovan Preston <dp at>

	* Added nevow.canvas, an experimental module similar to LivePage
	which provides a Python server-side API for drawing arbitrary lines,
	curves, and text in the browser. The implementation is socket-based
	and asynchronous, so the server can issue drawing commands to the
	client at any time.

	The idea is to provide a server-side API to the Python programmer 
	and shield them from implementation details, but the current
	implementation uses a pre-compiled Flash movie (which never changes;
	we are not generating Flash bytecodes). An implementation using SVG
	or Safari's Canvas (nevow.canvas was written before the Safari Canvas
	announcement) would be possible.

2004-05-26	Donovan Preston	<dp at>

	* Add URLOverlay.keep,  an API which lets you specify which query args 
	will be carried on from the current page render into the new URL.

2004-05-24	Matt Goodall <matt at>

	* Extracted Fragment from Page. Hopefully,  it will make it more obvious 
	that embedding an object with data_ and render_ methods in a stan tree is
	possible without using something as "heavy" as Page which is really meant
	to be a web resource.

2004-05-23	Donovan Preston	<dp at>

	* Added some useful APIs to LiveEvil for manipulating the client-side

		- flt(stan): Flatten some stan, quoting apostrophes as
		as appropriate for embedding in javascript

		- set(what, to): Set the contents of the client-side node
		with the id 'what' to the stan 'to'.

		- append(where, what): Append the stan 'what' to the client-
		side node with the id 'where'

		- alert(what): Show an alert to the user with the text "what"

Valentino Volonghi aka Dialtone
Linux User #310274, Proud Gentoo User
Home Page:

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