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• Is there a recommended way to use the Observer pattern in MVP using GWT?

  - by Tomislav Nakic-Alfirevic

  I am thinking about implementing a user interface according to the MVP pattern using GWT, but have doubts about how to proceed. These are (some of) my goals: - the presenter knows nothing about the UI technology (i.e. uses nothing from com.google.*) - the view knows nothing about the model or the presenter - the model knows nothing of the view or the presenter (...obviously) I would place an interface between the view and the presenter and use the Observer pattern to decouple the two: the view generates events and the presenter gets notified. What confuses me is that java.util.Observer and java.util.Observable are not supported in GWT. This suggests that what I'm doing is not the recommended way to do it, as far as GWT is concerned, which leads me to my questions: what is the recommended way to implement MVP using GWT, specifically with the above goals in mind? How would you do it?

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• are there any negative implications of sourcing a javascript file that does not actually exist?

  - by dreftymac

  If you do script src="/path/to/nonexistent/file.js" in an HTML file and call that in a browser, and there are no dependencies or resources anywhere else in the HTML file that expect the file or code therein to actually exist, is there anything inherently bad-practice about doing this? Yes, it is an odd question. The rationale is the developer is dealing with a CMS that allows custom (self-contained) javascript files to be provided in certain circumstances. The problem is the CMS is not very flexible when it comes to creating conditional includes for javascript. Therefore it is easier to just make references to the self-contained js files regardless of whether they are actually at the specified path. Since no errors are displayed to the user, should this practice be considered a viable option?

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• Why would it be a bad idea to have database connection open between client requests?

  - by AspOnMyNet

  1) Book I’m reading argues that connections shouldn’t be opened between client requests, since they are a finite resource. I realize that max pool size can quickly be reached and thus any further attempts to open a connection will be queued until connection becomes available and for that reason it would be imperative that we release connection as soon as possible. But assuming all request will open connection to the same DB, then I’m not sure how having a connection open between two client requests would be any less efficient than having each request first acquiring a connection from connection pool and later returning that object to connection pool? 2) Book also recommends that when database code is encapsulated in a dedicated data access class, then method M opening a database connection should also close that connection. a) I assume one reason why M should also close it, is because if method M opening the connection doesn’t also close it, but instead this connection object is used inside several methods, then it’s more likely that a programmer will forget to close it. b) Are there any other reasons why a method opening the connection should also close it? thanx

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• Best practice regarding returning from using blocks

  - by abatishchev

  Which way is better practice: return a value from a method inside an using statement or declare a variable before, set it inside and return it after? public int Foo() { using(..) { return bar; } } or public int Foo() { var b = null; using(..) { b = bar; } return b; }

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• Will asking users to upgrade their browser cause issues?

  - by John Isaacks

  Ok I am considering putting up something asking ie6 users to upgrade their browser. However, I am concerned that users will upgrade it, not like it. Then blame me. Is this a real concern? am I going to get people calling me asking me how to use their new browser or how to get their old one back? Whats your thought on this topic? Thanks!!

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• Is a "factory" method the right pattern?

  - by jdt141

  Hey all - So I'm working to improve an existing implementation. I have a number of polymorphic classes that are all composed into a higher level container class. The problem I'm dealing with at the moment is that the higher level container class, well, sucks. It looks something like this, which I really don't have a problem with (as the polymorphic classes in the container should be public). My real issue is the constructor... /* * class1 and class 2 derive from the same superclass */ class Container { public: boost::shared_ptr<ComposedClass1> class1; boost::shared_ptr<ComposedClass2> class2; private: ... } /* * Constructor - builds the objects that we need in this container. */ Container::Container(some params) { class1.reset(new ComposedClass1(...)); class2.reset(new ComposedClass2(...)); } What I really need is to make this container class more re-usable. By hard-coding up the member objects and instantiating them, it basically isn't and can only be used once. A factory is one way to build what I need (potentially by supplying a list of objects and their specific types to be created?) Other ways to get around this problem? Seems like someone should have solved it before... Thanks!

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• Can an app use the clipboard for its own purposes? (read: who owns the clipboard?)

  - by eran

  In PowerBuilder's IDE, the code autocomplete feature uses the clipboard to communicate the completed text to the code window. By doing so, it overrides whatever was stored on the clipboard before. So, if you had the winning numbers of the next lottary stored on your clipboard, and you used the autocomplete to turn m_goodfor into m_goodfornothing, you've just lost your only chance of ever getting rich, and you're left with nothing on your clipboard. Features like that are the reason I hate software. It looks like it was implemented by some intern that noone was looking after. However, there's also a chance I got all worked up for nothing, and making such use of the clipboard is absolutely legit. So, can an app use the clipboard for its own purposes? Who is considered the owner of the clipboard? (Bonus votes to whoever puts himself in place of the feature's programmer, and provides some reasoning for this being done on purpose, assuming the users would actually benefite from it)

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• Bi-directional view model syncing with "live" collections and properties (MVVM)

  - by Schneider

  I am getting my knickers in a twist recently about View Models (VM). Just like this guy I have come to the conclusion that the collections I need to expose on my VM typically contain a different type to the collections exposed on my business objects. Hence there must be a bi-directional mapping or transformation between these two types. (Just to complicate things, on my project this data is "Live" such that as soon as you change a property it gets transmitted to other computers) I can just about cope with that concept, using a framework like Truss, although I suspect there will be a nasty surprise somewhere within. Not only must objects be transformed but a synchronization between these two collections is required. (Just to complicate things I can think of cases where the VM collection might be a subset or union of business object collections, not simply a 1:1 synchronization). I can see how to do a one-way "live" sync, using a replicating ObservableCollection or something like CLINQ. The problem then becomes: What is the best way to create/delete items? Bi-directinal sync does not seem to be on the cards - I have found no such examples, and the only class that supports anything remotely like that is the ListCollectionView. Would bi-directional sync even be a sensible way to add back into the business object collection? All the samples I have seen never seem to tackle anything this "complex". So my question is: How do you solve this? Is there some technique to update the model collections from the VM? What is the best general approach to this?

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• Spring online repository for Maven

  - by Fortyrunner

  I've just installed Maven2 for the first time. By default it pulls down a few useful jars into a local project: jakarta-commons, junit etc. I wanted to pull in the latest Spring release (2.5.6 at the time of writing). But the online repositories I looked at (iBiblio and Maven) only had much older versions of Spring libraries. Are there any other repositories that are kept up to date? What is the best practice here; can we maintain them ourselves? I would be prepared to help out maintaining this stuff!

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• ASP.NET MVC IoC usability

  - by Andrew Florko

  Hello everybody, How often do you use IoC for controllers/DAL in real projects? IoC allows to abstract application from concrete implementation with additional layer of interfaces that should be implemented. But how often concrete implementation changes? Should we really have to do job twice adding method to interface then the implementation if implementation hardly will ever be changed? I took part in about 10 asp.net projects and DAL (ORM-like and not) was never rewritten completely. Watching lots of videos I clearly understand that IoC "is cool" and the really nice way to program, but does it really needed?

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• How Can I up my Street Cred in the coding world

  - by RedEye

  I know this isn't directly related to a specific coding problem. It's a more general programming question. I'm a n00b... Been coding for 1 year, and it's where I belong. I want to get hardcore and put everything I have into it. I started with C++ and now I'm into C#. I love it all. What can I do to up my game and up my respect in the programming world?

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• When is JavaScript's eval() not evil?

  - by Richard Turner

  I'm writing some JavaScript to parse user-entered functions (for spreadsheet-like functionality). Having parsed the formula I could convert it into JavaScript and run eval() on it to yield the result. However, I've always shied away from using eval() if I can avoid it because it's evil (and, rightly or wrongly, I've always thought it is even more evil in JavaScript because the code to be evaluated might be changed by the user). Obviously one has to use eval() to parse JSON (I presume that JS libraries use eval() for this somewhere, even if they run the JSON through a regex check first), but when else, other than when manipulating JSON, it is OK to use eval()?

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• What should be the "trunk" development, or release

  - by Nix

  I have the unfortunate opportunity of source control via Borland's StarTeam. It unfortunately does very few things well, and one supreme weakness is its view management. I love SVN and come from an SVN mindset. Our issue is post production release we are spending countless hours merging changes into a "production support" environment. Please do not harass me this was not my doing, I inherited it and am trying to present a better way of managing the repository. It is not an option to switch to a different SCM tool. Current setup Product.1.0 (TRUNK, current production code, and at this level are pending bug fixes) Product.2.0(true trunk anything checked in gets tested, and then released next production cycle, a lot of changes occur in this view) My proposal is going to be to swap them, have all development be done on the trunk (Production), tag on releases, and as needed create child views to represent production support bug fixes. Production Production.2.0.SP.1 I can not find any documentation to support the above proposal so I am trying to get feedback on whether or not the change is a good idea and if there is anything you would recommend doing differently.

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• quantity of measurable units design pattern

  - by Berryl

  Hello I am thinking through a nice pattern to be useful across domains of measurable units (ie, Length, Time) and came up with the following use case and initial classes, and of course, questions! 1) Does a Composite pattern help or complicate? 2) Should the Convert method(s) in the ComposityNode be a separate converter class? All comments appreciated. Cheers, Berryl Example Use Case: var inch = new ConvertableUnit("inch", 1) var foot = new ConvertableUnit("foot", 12) var imperialUnits = new CompositeConvertableUnit("imperial units", .024) imperialUnits.AddChild(inch) imperialUnits.AddChild(foot) var meter = new ConvertableUnit("meter", 1) var millimeter = new ConvertableUnit("millimeter ", .001) var imperialUnits = new CompositeConvertableUnit("metric units", 1) imperialUnits.AddChild(meter) imperialUnits.AddChild(millimeter) var oneInch = new Quantity(1, inch); var oneFoot = new Quantity(1, foot); oneFoot.ToBase() // "12 inches" var oneMeter = new Quantity(1, meter); oneInch.ToBase() // .024 meters Possible Solution ConvertableUnit : Node double Rate string Name Quantity ConvertableUnit Unit double Amount CompositeConvertableUnit : Node ISet<ConvertableUnit> _children ConvertableUnit BaseUnit {get{ return _children.Where(c=>c.Rate == 1).First() } } Quantity ConvertTo(Quantity from, Quantity to) Quantity ToBase(Quantity from);

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• ORM/ADO.NET data services for asp.net-mvc web application..

  - by chandru_cp

  As i am a beginner to asp.net-mvc which should i use ORM/ADO.NET data services.... As far as i see all the examples are only with ORM support.... So experts please guide me on this...

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• Format for storing contacts in a database

  - by Gart

  I'm thinking of the best way to store personal contacts in a database for a business application. The traditional and straightforward approach would be to create a table with columns for each element, i.e. Name, Telephone Number, Job title, Address, etc... However, there are known industry standards for this kind of data, like for example vCard, or hCard, or vCard-RDF/XML or even Windows Contacts XML Schema. Utilizing an standard format would offer some benefits, like inter-operablilty with other systems. But how can I decide which method to use? The requirements are mainly to store the data. Search and ordering queries are highly unlikely but possible. The volume of the data is 100,000 records at maximum. My database engine supports native XML columns. I have been thinking to use some XML-based format to store the personal contacts. Then it will be possible to utilize XML indexes on this data, if searching and ordering is needed. Is this a good approach? Which contacts format and schema would you recommend for this?

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• Best practice - When to evaluate conditionals of function execution

  - by Tesserex

  If I have a function called from a few places, and it requires some condition to be met for anything it does to execute, where should that condition be checked? In my case, it's for drawing - if the mouse button is held down, then execute the drawing logic (this is being done in the mouse movement handler for when you drag.) Option one says put it in the function so that it's guaranteed to be checked. Abstracted, if you will. public function Foo() { DoThing(); } private function DoThing() { if (!condition) return; // do stuff } The problem I have with this is that when reading the code of Foo, which may be far away from DoThing, it looks like a bug. The first thought is that the condition isn't being checked. Option two, then, is to check before calling. public function Foo() { if (condition) DoThing(); } This reads better, but now you have to worry about checking from everywhere you call it. Option three is to rename the function to be more descriptive. public function Foo() { DoThingOnlyIfCondition(); } private function DoThingOnlyIfCondition() { if (!condition) return; // do stuff } Is this the "correct" solution? Or is this going a bit too far? I feel like if everything were like this function names would start to duplicate their code. About this being subjective: of course it is, and there may not be a right answer, but I think it's still perfectly at home here. Getting advice from better programmers than I is the second best way to learn. Subjective questions are exactly the kind of thing Google can't answer.

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• How to build a JSON response by combining @foo.to_json(options) and @bars.to_json(options) in Rails

  - by smotchkkiss

  First, the desired result I have User and Item models. I'd like to build a JSON response that looks like this: { "user": {"username":"Bob!","foo":"whatever","bar":"hello!"}, "items": [ {"id":1, "name":"one", "zim":"planet", "gir":"earth"}, {"id":2, "name":"two", "zim":"planet", "gir":"mars"} ] } However, my User and Item model have more attributes than just those. I found a way to get this to work, but beware, it's not pretty... Please help... My hacks home_controller.rb class HomeController < ApplicationController def observe respond_to do |format| format.js { render :json => Observation.new(current_user, @items).to_json } end end end observation.rb # NOTE: this is not a subclass of ActiveRecord::Base # this class just serves as a container to aggregate all "observable" objects class Observation attr_accessor :user, :items def initialize(user, items) self.user = user self.items = items end # The JSON needs to be decoded before it's sent to the `to_json` method in the home_controller otherwise the JSON will be escaped... # What a mess! def to_json { :user => ActiveSupport::JSON.decode(user.to_json(:only => :username, :methods => [:foo, :bar])), :items => ActiveSupport::JSON.decode(auctions.to_json(:only => [:id, :name], :methods => [:zim, :gir])) } end end

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• Optimal UI For Single Zip Code Entry on iPhone

  - by sylvanaar

  I need to prompt the user to enter his/her zip code at certain times in my iPhone application. I cannot store it or get it from the user's current location. What is the optimal input method? I started with a 5 wheel picker. This seemed like a bad direction, so I opted for a PIN-like entry screen. My implepentation is about the same as the 'enter passcode' screen you see when unlocking the iphone - including automatically ending input on the 5th digit instead of providing a return/enter button. Does this seem optimal? Or is there a better way? Note: I only need to accept a 5 digit US zip code.

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• Book/tutorial that teaches how to make programs that are easy to maintain and are less coupled?

  - by grokker

  Hi, I'm a PHP programmer and I really want to increase the quality of my code and most importantly I want to be better at programming. What book, tutorial or article would you guys suggest that I read that teaches how to make programs that are less coupled and easy to maintain? Are there any specific tips for PHP especially for the CakePHP framework? Thanks in advance!

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• What is a best practice of writing hash function in java?

  - by den-javamaniac

  Hi. I'm wondering what is the best practice for writing #hashCode() method in java. Good description can be found here. Is it that good?

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• Which to use? Visual Studio Development Server or Local IIS Web server?

  - by mattruma

  I've always wondered about this ... and thankfully, now have a good environment of experts to ask this question. When creating a web application project which web server is the most expedient to use? This is a duplicate question ... http://stackoverflow.com/questions/281667/asp-net-development-server-or-localhost-iis ... my bad!

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• How can i return abstract class from any factory?

  - by programmerist

  using System; using System.Collections.Generic; using System.Linq; using System.Web; namespace EfTestFactory { public abstract class _Company { public abstract List<Personel> GetPersonel(); public abstract List<Prim> GetPrim(); public abstract List<Finans> GetFinans(); } public abstract class _Radyoloji { public abstract List<string> GetRadyoloji(); } public abstract class _Satis { public abstract List<string> GetSatis(); } public abstract class _Muayene { public abstract List<string> GetMuayene(); } public class Company : _Company { public override List<Personel> GetPersonel() { throw new NotImplementedException(); } public override List<Prim> GetPrim() { throw new NotImplementedException(); } public override List<Finans> GetFinans() { throw new NotImplementedException(); } } public class Radyoloji : _Radyoloji { public override List<string> GetRadyoloji() { throw new NotImplementedException(); } } public class Satis : _Satis { public override List<string> GetSatis() { throw new NotImplementedException(); } } public class Muayene : _Muayene { public override List<string> GetMuayene() { throw new NotImplementedException(); } } public class GenoTipController { public object CreateByEnum(DataModelType modeltype) { string enumText = modeltype.ToString(); // will return for example "Company" Type classType = Type.GetType(enumText); // the Type for Company class object t = Activator.CreateInstance(classType); // create an instance of Company class return t; } } public class AntsController { static Dictionary<DataModelType, Func<object>> s_creators = new Dictionary<DataModelType, Func<object>>() { { DataModelType.Radyoloji, () => new _Radyoloji() }, { DataModelType.Company, () => new _Company() }, { DataModelType.Muayene, () => new _Muayene() }, { DataModelType.Satis, () => new _Satis() }, }; public object CreateByEnum(DataModelType modeltype) { return s_creators[modeltype](); } } public class CompanyView { public static List<Personel> GetPersonel() { GenoTipController controller = new GenoTipController(); _Company company = controller.CreateByEnum(DataModelType.Company) as _Company; return company.GetPersonel(); } } public enum DataModelType { Radyoloji, Satis, Muayene, Company } } if i write above codes i see some error: Cannot create an instance of abstract class or interface 'EfTestFactory_Company'How can i solve it? Look please below pic.

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• Rounded Corners Image Change on Hover

  - by Sarfraz

  Hello, I created a rounded box/button and sliced its first corner, the middle bar (which repeats horizontally to adjust the width of the button text/content) and the last corner and used following markup: <div id="left-corner"></div> <div id="middle-bar">About Us</div> <div id="right-corner"></div> These divs have corresponding images from CSS and are floated left. Those three divs create a single rounded button wiht text About Us which is fine. Problem: I have also created similar three slices of hover images but I wonder how to apply hover to those buttons because if I use :hover with these hovered slices, then even hovering on corner images also creates hovering effect. One alternative is to use fixed width buttons and slice buttons completely but I do not want to do that.

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• Naming convention for utility classes in Java

  - by Zarjay

  When writing utility classes in Java, what are some good guidelines to follow? Should packges be "util" or "utils"? Is it ClassUtil or ClassUtils? When is a class a "Helper" or a "Utility"? Utility or Utilities? Or do you use a mixture of them? The standard Java library uses both Utils and Utilities: javax.swing.Utilities javax.print.attribute.AttributeSetUtilities javax.swing.plaf.basic.BasicGraphicsUtils Apache uses a variety of Util and Utils, although mostly Utils: org.apache.commons.modeler.util.DomUtil org.apache.commons.modeler.util.IntrospectionUtils org.apache.commons.io.FileSystemUtils org.apache.lucene.wordnet.AnalyzerUtil org.apache.lucene.util.ArrayUtil org.apache.lucene.xmlparser.DOMUtils Spring uses a lot of Helper and Utils classes: org.springframework.web.util.UrlPathHelper org.springframework.core.ReflectiveVisitorHelper org.springframework.core.NestedExceptionUtils org.springframework.util.NumberUtils So, how do you name your utility classes?

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