Tapestry gives you other options besides subclasses to provide the custom behavior of your components.
You can also use aggregation. Please try and take a look at helper beans. Helper beans are JavaBeans declared in your component specification. You can also configure helper beans, setting the properties of the beans. (This actually based on some experience with ATG Dynamo, which built their entire system around beans). Anyway, you could put the logic for assembling a context into such a bean and, with the appropriate bindings and initializations make it work. Is this more effort than subclassing? I guess that's your choice. -- [EMAIL PROTECTED] http://tapestry.sf.net > Thanks. I guess I'm looking for the context-binding that allows multiple > values in-place which you mentioned. > > The reason I wanted this is because we have trying been to minimize the > amount of java code needed to do things. Our framework works with List and > Maps that are generated dynamically so we don't need to write much java code > for specific pages. It goes against the grain to have to write a method that > packages two parameters together since it means we need to 'hard-code' > property names into the java class. Up until now we have been able to keep > property name information exclusively in the component specifications. > > No problem though, we can just bite the bullet and write some java. > > -----Original Message----- > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] > Sent: Friday, May 03, 2002 11:29 AM > To: Phil Surette > Cc: Tapestry Developer (E-mail) > Subject: Re: [Tapestry-developer] multi-value contexts for Direct > components > > > The Direct component is pretty flexible with its context > parameter. The value bound to the parameter can be a > single String, and array of Strings, a Collection of > Strings or an Iterator (of Strings). Please check the > class documentation. > > In my code, when I need to put multiple values into the > context (which is fairly rare ... see note at end), I > create a method that assembles the values as a list. > This is a common Tapestry pattern ... the controller > object (the Java object for the component) massaging or > otherwise brokering data for the components it contains. > > I have thought about creating a <context-binding> that > would allow you to build the context in-place (it would > be a list of bindings). Haven't gone anywhere with > that, as yet .. it hasn't been a priority. > > Why You Rarely Need Multiple Values > > Most of the time, the need to encode lots and lots of > parameters into the URL is caused by the necessity of > encoding dispatch infomation with the actual parameter > information. In some ways, a URL is like a method > invocation; part of the URL identifies an object or > component, part identifies an operation, the rest are > parameters to that operation. > > In Tapestry terms, the URL identifies a service and > service context ... that effectively identifies the > component and operation. The context becomes the > parameters to that operation. Tapestry does all the > work of encoding the service and service context. > > For example, say you have a page with three links. Each > links should trigger a different bit of behavior, i.e., > a different method. > > In Struts/JSP, you have to create a servlet or action > and define parameters to identify which of the three > behaviors to trigger. Your servlet has to extract a > parameter and dispatch to the correct method based on > its value. > > > In Tapestry, you define three listener methods, and > create three instance of Direct, each bound to the > appropriate listener method. That's it. > > A Side Note About Robustness > > Tapestry will detect if you reference an unknown > component (not likely, since it builds the URL) or an > unknown listener method ... you'll get a screenful of > exception page to help you understand what you, the > developer, have done wrong. In a Struts/JSP solution, > error cases are your reponsibility ... not just to > correct, but to identify and report. > > > > -- > [EMAIL PROTECTED] > > http://tapestry.sf.net > > How do you pass multiple values to a Direct's context? > > > > I've tried each of the following but in both cases the corresponding > > editFile method gets only one value. > > > > <component id="editFile" type="Direct"> > > <binding name="listener" property-path="listeners.editFile"/> > > <binding name="context" property-path="components.files.value.id"/> > > <binding name="context" property-path="profile.id"/> > > </component> > > > > <component id="editFile" type="Direct"> > > <binding name="listener" property-path="listeners.editFile"/> > > <binding name="context" > > property-path="components.files.value.id,profile.id"/> > > </component> > > > > re: brief description of how we're using tapestry, I'm not sure how much I > > can say, will get back to you when possible. _______________________________________________________________ Have big pipes? 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