Yours is a very good point, but it leaves unanswered the crucial question: when IS it advantageous to use the declarative approach instead? I am not convinced that Google's choice of which declarations to offer makes this decision straightforward, far less obvious.
On Jan 17, 11:40 am, Bob Kerns <r...@acm.org> wrote: > MVC separation of View and Controller -- Obsolete????? That is > something I have never heard of. Could you elucidate? What replaces > it? The separation in MVC exists for very specific benefits. If you > view it as obsolete, you must have a New Idea -- MVC started as a New > Idea, and I like New Ideas.... (Don't worry about whether the idea is > good enough. The courage to be wrong is the best tool for both > learning and creating something new). > > A key one of those benefits is that the separation allows you to > substitute alternate views. This can come up during localization, and > when accommodating different device sizes and geometries. With > localization in particular, having it be part of the XML is an > important advantage, as you don't want a localization service altering > your Java code! > > At the same time, the ability to do it from code is there to give > flexibility when the XML falls short. But it needn't be all one or the > other! For example, it is quite usual to use XML to describe the items > in a ListView, and inflate the appropriate XML file for the items from > Java code. You can apply the same strategy at any level -- for > example, an outer template that gives the outer structure, select the > components that plug into it via Java code, and then inflate those > components, and plug them into the outer template. > > This is very easy to do. You use ID's on the parents of items in the > template, and findViewFromId to locate them, and inflate the children > (perhaps a variable number of children), make any adjustments, and add > them. > > Re: your second sentence: You HAVE the power to create your own layout > classes. Use it! If you want to create a Carousel layout that arranges > a set of views into a carousel, write that algorithm in Java as an > actual layout class, then reference it in your XML. If the set of > views in the Carousel is dynamic, make it work with an Adapter, > similar to how ListView works, and inflate each subview dynamically. > > Oh, and a postscript: I use XSLT to strip out or disable unwanted > views in the free and paid versions of my app. (Views related to > features not present, or ads). This is harder to do reliably with Java > code. > > In general using declarative languages where possible is a time-tested > strategy for making software simpler to work with, both for humans and > programs, and making it easier to be consistent. This is a matter of > *deliberately* giving up certain flexibility, compared to imperative > programming. By giving up the unfettered flexibility of a Turing > Machine, you gain a host of benefits and lose a ton of potential > complexity. (An infinite amount of potential complexity, really!). > > It is not ALWAYS the choice you want to make. But if what you want to > do fits within the declarative framework, you are almost always better > off sticking within the declarative framework, and if it doesn't QUITE > fit, you're better off using the declarative framework, with a minimum > of imperative programming where necessary. > > On Jan 13, 7:04 pm, Toby <t...@tobiah.org> wrote:> Ok, we've thought about > MVC paradigms for our company, > > but unless you really need to hide the code from some > > "Designer" I can't see the benefits. > > > I want the power of the computer language at hand to allow me > > to create layouts dynamically. I've been scolded about > > that by one most learned participant of this list. I don't see > > why. I want to use the base language (here java) to > > create layouts. Why on earth does Google go for what > > I (Certainly Erroneously given the body of individuals > > to which I am now speaking) perceive to be an obsolete > > separation between Controller and View? > > > Please enlighten me, you undisputed masters of this > > newly found world of which I hope to convincingly call > > myself a member in short. > > > Thanks, > > > Tobiah > > -- You received this message because you are subscribed to the Google Groups "Android Developers" group. To post to this group, send email to android-developers@googlegroups.com To unsubscribe from this group, send email to android-developers+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/android-developers?hl=en
