I'm learning GWT and have started to get the hang of it. I'm at the point where my code is getting to be a spaghetti mess so I'm going back and factoring reasonable bits of it out as Composites. The first problem I ran into was that my tool support failed to give the new Composite class an initWidget() method. It did include a default constructor.
For the time being, I've simply filled in my overridden initWidget() method with a call to super(initWidget(w)) My project compiles and runs as expected, though I feel as though I must be missing something.
What should I keep in mind when overriding init and what if anything do i need to place in the constructor. Is there anything else that I need to know or does it just boil down to regular old Java after this?
Clarification - It has occurred to me that there are probably different answers to this question depending on whether you intend to release said Composite classes as part of a library or simply part of your stand-alone app. I in particular have no intention at this time of developing externally useful components (mainly because I'm so green in this particular technology.)
Thanks!
I'm not sure if I understand what you are trying to do. But for all the Composite's I've written I've never overridden the initWidget method. Because Composite itself doesn't need to be initialized with a constructor, i.e. no need to call super() my constructors of widgets extending composite look something like:
public mywidget() {
SomePanel p = new SomePanel();
....
initWidget(p);
}
As a best practice, imo, only the widget extending Composite should call it's 'own' initWidget.
"GWT Conference: Best Practices for Building Libraries" gives a couple of tips. You should also look at the source of GWT and at the source of one of the libraries for GWT (like gwt-ext)
[EDIT] I just saw another option: suco. From the description:
A micro library that helps to maintain your GWT client code clean and modular.
Related
Being new to flutter and dart, I am looking for ways to structure my projects. I have found that the Repository pattern made its way to dart (I have a strong Java background), but I have found that there's not the necessary tools yet to properly implement a repository.
How I would normally approach this is to first create the simple straightforward methods. I ended up with the following dart code:
abstract class CategoryRepository {
Future<List<Category>> getCategories();
Future<Category?> getCategoryById(String id);
}
All is good. But now imagine I have a PostRepository, and I only want to return posts of a specific category? I am missing a standardized way in flutter how to add conditions to my repository select methods. I cannot believe nobody has written something for this purpose before so I am doubting whether I am on the right track here. Maybe my Java background is throwing me off.
In Java (specifically Spring JPA) I am used to specifications, predicates and criteria as documented here.
In .NET you can implement select methods of a repository pattern with the Expression class which allows you to use LINQ to add select criteria as documented here.
For Flutter or Dart, what would be the equivalent? Or am I on the wrong track?
I have found the flutter_repository package, but it is deprecated (without a reason). Looking at the documentation it indeed had Specifications which are used to add conditions. This would be exactly what I expect/need, but again it's deprecated.
This is where I cannot find the information publicly anymore and am questioning "how to properly implement repository in flutter/dart", hence the reason for posting this.
I'm wondering is there a similar framework like Vaadin built on top of GWT which wraps the original GWT components but with server-side only event handling? (I know that Vaadin is built on top of GWT. I'm looking for an alternative solution.)
Vaadin is nice because of it's precompiled nature. I found compile times with GWT horrific the last time i've worked with it. Also it's a bit easier to maintain security if event handling code runs on the server. It would be nice if the standard GWT could be used in a similar way.
I don't think there is another like vaadin. and vaadin is already server-side..
see this http://vaadin.com/learn for more info
Have you seen this? - http://code.google.com/p/gwteventservice/
For server-side alternative, you might take at a look at ZK too.
Notice that its client side is based on jQuery, not GWT. However, you won't notice it at all since they both are server-side solutions and using pure Java.
Event handlers that you normally deal with are in server-side Java code. Consider this:
final Button testButton = new Button("Test Button");
testButton.addListener(new Button.ClickListener()
{
#Override
public void buttonClick(ClickEvent event)
{
mainWindow.showNotification("I am server-side code!");
}
});
As you said, you need to compile GWT code only when adding a custom component to your code. Vaadin's built in components are already compiled and put in the jar file. Although sometimes your IDE might detect your project as a GWT project and try to compile the widgetsets every time you change the code, when you might want to ask it to ignore.
If you look for alternatives to Vaadin you might have a look at Echo2.
I have seen that GWT framework is having generator feature.
In what case we have to use gwt generator option and why it is needed?
Can anyone tell me simply why,what is gwt generator? Done some googling. But not much helpful stuffs...
From this tutorial:
Generators allow the GWT coder to generate Java code at compile time and have it then be compiled along with the rest of the project into JavaScript.
This tutorial uses the example of generating a Map of values at compile time based on a properties file.
I've done GWT development for 3 years now and I've written one generator :) I've written a couple of linkers for experimental purposes so I think they are more common, though still rare. The classic case is where you want to write
X x = GWT.create(X.class)
and have the particular subclass or implementation of X constructed at compile time based on, perhaps, annotations in the provided X class or interface. GWT uses them for things like the CSSResource.
Search for "GWT Generator Experiments" site:development.lombardi.com on google for some info about what I did.
One of the use cases is to mimic reflection on the client side by building a factory class on the fly. I remember answering a question posted by you earlier on how to do this
How to create new instance from class name in gwt?
So i guess you already know the application. What else are you looking for? Can you be precise?
I've started using GWT Generators where I needed Java Reflection. I've documented One of the use cases for using GWT generators here:
http://jpereira.eu/2011/01/30/wheres-my-java-reflection/
Hope it helps.
If you refer to code generator, yes, there will a tool supporting GWT 2.1 code generation. For more details and a quick start, see http://www.springsource.org/roo/start
A general roo intro is here http://blog.springsource.com/2009/05/01/roo-part-1/
Another visual tutorial is at http://www.thescreencast.com/2010/05/how-to-gwt-roo.html
Check out this implementation:
http://samuelschmid.blogspot.com/2012/05/using-generator-for-generic-class.html
You can create new Instances of classes on client with foo.newInstance("fully.qualified.class.name");
I'm working on a GWT project and I find it very tedious to have to add a function to my servlet, then copy and paste the function signature into my Service interface, then copy and paste it into my ServiceAsync interface and change the return parameter to be a callback. Is there a tool or a setting where I can just add public methods to my class and they can get copied into the other interfaces? Even if its not automatic it would be nice to be able to select specific methods and have them copied automatically.
I'm using eclipse and ideally it would update my interface each time I save implementation since thats when it checks my code and complains that my changes break the interface.
If you add the method to your *Service interface, then Eclipse can auto-generate the method ("Add unimplemented methods...") in your *ServiceImpl servlet, which you can then just fill in. Also, if you've got the Google Eclipse plugin installed, it will underline the new method in your *Service interface and complain that it's not in the *ServiceAsync. It might have a CTRL + 1 option to generate it in that interface as well.
You don't really need a tool. Just factor out the many RPC methods by just one method that takes a Request/Response. all you need to do is create subclasses of Request/Response and you don't need to think about adding new methods in the 2 interfaces.
You can use Google Guice on the server side to map the incomming request to a class handling the call... or you could use a visitor approach to forward the incoming request to the code handling the request (without resorting on a big instanceof construct).
Instantiations WindowBuilder GWT Designer does exactly what you are looking for.
The RemoteService Wizard will create all three files at the same time as well as keep them in sync as you make changes.
http://www.instantiations.com/windowbuilder/gwtdesigner/index.html
FWIW - I am only a user/purchaser of this product. I am not employed or in any other way related to Instantiations.
I eventually couldn't get any further with my program due to the various shortcomings of VB.NET (bad audio support, no reading events in the middle of execution, very weak keyboard input, etc). So I tried SDL.NET 6.1.
Despite its terrible documentation, I was able to fix my code to use it and I love it!
But there's a problem. I don't know how to set up my application settings for it. The Startup Object definitely should be a class (the examples always are in classes, never modules), but a startup class specifically has to be a form! This is bad because SDL makes its own window via SetVideoMode; you don't need a form. So when the form constructor New() finishes, a useless form is created and you have two windows.
I tried placing a call to the game engine loop within New() so that the game starts up without New() ever finishing. The game runs normally, and this solves the "second window" problem... but it can't be closed! X button does nothing, calls to Events.QuitApplication or Me.Close are blatantly ignored, etc.
I'm stumped. It seems I need to set a non-form class as the startup object, but it won't let me.
Oh, by the way, it seems that there are two things called "SDL NET". To clarify, I'm using this one, which exists in the SdlDotNet namespace.
Oh, I forgot to mention, I also noticed that a lot of the examples have a line that says "[STAThread]". Is this is important?
EDIT:
I've already received and accepted an answer for my question, but I want to tell other people what the problem is with exiting/closing the app, even though that wasn't my question:
While SDL.NET allows you to receive input and run other events without having to stop running logic, the application still cannot quit while logic is being run. So I find the best way to tell your SDL.NET application to Quit in the middle of running logic is to use the following TWO lines:
SdlDotNet.Core.Events.QuitApplication
End
Place these in the handler for the SdlDotNet.Core.Events.Quit event, as well as anywhere else you want your program to quit.
The Startup Object definitely should be a class (the examples always are in classes, never modules)
Here's your mistake. There's no real difference between a class and a VB module from CLR perspective. So just make it a module with Main and go on. There is no need for a class. I suspect you're looking at C# examples, which use classes - but that's because there is no such thing as a module in C#.
[STAThread] probably won't make any difference for SDL. It is important for UI applications (both WinForms and WPF require it), but I don't think that SDL does any COM calls, so it shouldn't care whether your thread is STA or not. It's just something that Visual Studio puts on Main in new projects by default.