Re: Plastic: An ASM wrapper for Tapestry 5.3

Howard,

  You may want to start with providing a 5 minute howto tutorial or a cookbook.
  Learning a new framework by the javadocs is not exactly trivial task...

  regards,
  Eugene


On Thu, Apr 21, 2011 at 3:59 PM, Howard Lewis Ship <[email protected]> wrote:
> I'm not sure how many of you are aware of Tapestry
> (http://tapestry.apache.org/) ... it's a sophisticated Java web
> application framework.  At its core, it does some sophisticated
> meta-programming on Java classes, transforming them at load time to
> give them a number of new capabilities and such. This has built up in
> Tapestry 5 over the last few years, using a wrapper around Javassist.
>
> However, Javassist is poorly documented, supported and maintained.
> It's also repeatedly caused problems with code compiled for JDK 1.6.
> Several months ago, I decided to see if I could port my highest level
> abstractions from Javassist to ASM (in fact, the move to higher
> abstractions goes back a year or more).
>
> The result is Plastic.  Plastic is a layer on top of ASM.  It entirely
> hides the ASM APIs.
>
> The JavaDoc is here (from Tapestry's continuous integration build):
>
> https://builds.apache.org/hudson/job/tapestry-trunk-freestyle/ws/trunk/build/documentation/javadocs/org/apache/tapestry5/plastic/package-summary.html
>
> (start with PlasticManager and PlasticClass)
>
> Plastic is used in two ways:
>
> 1) To create new objects, typically proxy objects implementing one or
> more interfaces
>
> 2) To instrument existing code, modifying its implementation
> incrementally as classes are individually loaded
>
> In most cases, you add behavior by introducing new interfaces and new
> methods and by applying advice to existing methods.  For fields you
> may inject values into the field, or outright replace access to the
> field with delegation through a supplied FieldConduit.
>
> You also get efficient access to methods, regardless of visibility,
> via MethodHandle, as well as efficient access to fields (which are
> required to be private) via FieldHandle.
>
> Finally, there's a nice DSL, InstructionBuilder, used for providing
> the implementation of a method directly.
>
> Although Plastic is part of Tapestry, it is entirely usable outside of
> Tapestry; it's a sub-project of Tapestry with no dependencies (it even
> uses a repackaged copy of the ASM 3.3.1 source).  Tapestry 5.3,
> including Plastic, is currently in an alpha state.
>
> I'm generally quite pleased with how Plastic has come out, and I'd
> like to share it with others with a similar interest.
>
> Tapestry's inversion-of-control layer uses Plastic to generate various
> kinds of proxies, to handle everything from just-in-time
> initialization, to more advanced design patterns (such as
> chain-of-command), to crazy stuff such as allowing method invocations
> to return placeholder objects while computations execute on separate
> thread.
>
> In Tapestry's web layer, Plastic is used for additional types of
> proxies, and for the property expression language (Tapestry compiles
> template expressions such "user.name" directly to bytecode for optimal
> execution).
>
> In the next few weeks, I'll be converted the component class
> transformation part from the Javassist layer to Plastic.
>
> I'm very interested in comments and suggestions concerning Plastic.
>
> --
> Howard M. Lewis Ship
>
> Creator of Apache Tapestry
>
> The source for Tapestry training, mentoring and support. Contact me to
> learn how I can get you up and productive in Tapestry fast!
>
> (971) 678-5210
> http://howardlewisship.com
>
>
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