Is there a way to handle the application_start "event" without using the global.asax?
The best I can come up with is an HttpModule that checks some static variable on every begin_request, which is INCREDIBLY wasteful :(
Do I have any other options?
Thanks
AFAIK, the reflection-based "pseudo-events" in Global.asax are not accessible in any other way than by reflection. However, for the application_start event, you might be able to achieve similar functionality by overriding the Init() method on a subclass of HttpApplication. Some functionality might not be accessible, as it probably fires on a slightly different point in the lifecycle.
Alternatively, if you're going with an HttpModule, couldn't you just use the Init() method instead of begin_request?
If your code is existing in the website, you can use the largely undocumented 'AppInitialize' method. Add this static method to any class in your web project.
(Note: it will not work if contained in a compiled assembly within the site.)
For more info, search for "AppInitialize". (Ex: http://www.bing.com/search?q=appinitialize+msdn&src=IE-SearchBox&FORM=IE9bSRC)
Related
I have read the two other questions on SO regarding this and I wanted to know if there is a good solution for that now / best practice.
Long story short, we use an SDK which is written natively and we've wrapped it so that it works on Xamarin.Android and Xamarin.iOS. It has asynchronous callback methods. I need to call a method in the shared code when a callback is received in the Android project for instance.
There's a lot of info for doing the opposite - using DependencyService. How about in my scenario? Does anyone have experience with an app like this and what's the best approach to keep code clean and do this using MVVM?
The options I know are:
Using a static App instance - this is what we currently do.
MessagingCenter
Anything else?
Actually I've never seen anyone recommend usage of MessagingCenter for anything else than communication between ViewModels so I am not sure it is recommended here. Also, I need to know the sender object type so I need a reference to the class in the platform specific project.
I would recommend you to use messagingCenter to pass data or call method between shared project and platform project. You can just send a new object instead of the class in the platform specific project.
Also, have a look at using eventhandler as I mentioned in this answer may help someone who want to call from the shared project into the platform specific one.
BTW, I mean you can even pass an object as TSender if it is not necessary to use:
MessagingCenter.Send<Object>(new object(), "Hi");
MessagingCenter.Subscribe<Object>(new object(), "Hi", (sender) =>
{
// Do something whenever the "Hi" message is received
});
I am using Prism to navigate between views in my WPF application. One view in particular I've implemented with the IRegionMemberLifetime.KeepAlive => returns false; to create a new instance of the view every time we navigate to the view (we need to do this for display reasons). This view also hosts a custom win32 control that I need to do some cleanup in using IDisposable.Dispose. When I navigate to my view and then away from it, I'd expect Dispose to get called (to run cleanup). I was able to achieve this by implementing a custom region behavior as discussed here, https://github.com/PrismLibrary/Prism/issues/7. All this is working fine except everything gets marked for disposal but the GC doesn't actually get rid of anything. I'm using Autofac as my IOC container and after doing some research I've concluded the reason comes down to Autofac and lifetime scopes of IDisposables, https://nblumhardt.com/2011/01/an-autofac-lifetime-primer/. Basically Autofac holds references to the IDisposable and the GC won't get rid of the old view because of this. For instance I'm registering my view in the Module as _container.RegisterTypeForNavigation(); I'm not able to register this with any sort of lifetime and I'm not sure how I'd resolve this with a lifetime specified? When I call RegionManager.RequestNavigate I don't see any sort of overloads to specify lifetime? Any ideas would be appreciated.
RegisterTypeForNavigation essentially does builder.RegisterType(type).Named<object>(name); which you can do yourself, too, of course and apply any lifetime you desire. There's no magic in registering for navigation, RegisterTypeForNavigation is just a shorthand.
To make Autofac ignore the IDisposables, one can write
builder.RegisterType<SomeView>().Named<object>(typeof(SomeView).Name).ExternallyOwned();
From the docs:
Disabling Disposal
Components are owned by the container by default and will be disposed by it when appropriate. To disable this, register a component as having external ownership:
builder.RegisterType<SomeComponent>().ExternallyOwned();
The container will never call Dispose() on an object registered with external ownership. It is up to you to dispose of components registered in this fashion.
So extending #Haukinger answer. This is what finally worked for me:
//builder.RegisterTypeForNavigation<SomeView>();
builder.RegisterType<SomeView>().Named<object>
(typeof(SomeView).Name).ExternallyOwned();
That ExternallyOwned() signals to autofac that the user is going to handle calling dispose and that autofac shouldn't track the IDisposable.
I have a huge library of classes I copied and I want to set all methods in all classes to:
throw new NotImplementedException();
Does ReSharper have a way to do this globally over the whole solution?
You can do this using ReSharper's Search with Pattern feature in semi-automatic way, i would say. I'll better attach screenshot.
This way you replace all private instance methods in Solution. Then you need to replace all public, protected, internal, same with static and virtual keywords and you'll be there.
I made a settings page for my website. On this page the user is presented with a bunch of site wide settings they can manipulate. I made it so when the user selects a setting the page will automatically run an ajax request to send the setting to the database. My question is in how I do this.
At first I just did calls to the repository. One call to get the data back, put it into a ViewModel then give that ViewModel to the View and the ajax controller just sent the settings back to the database. This way seemed like the best at first especially for unit testing purposes since I could just pass in a fake repository if needed. Then for the user to get a setting they just called the repository and pass in the setting name they want.
Then I had a bright idea. I made a singleton class called SiteWideSettings and each possible setting on the site was a property of the site. When SiteSettings is called for the first time all of the settings are loaded. When Set is called on any of the properties it will call the repository function to send the setting. Now with my Settings view I'm just passing in SiteWideViewOptions.Current and on the ajax call I'm updating the property that was changed. This is working for me however it's not very unit testable since I can't really pass in a repository to a singleton's constructor since its constructor is private. What I currently have is working fine but I just don't feel like it's the best solution and unit testing isn't really possible here.
I'm thinking of one of the following but not sure which is the best.
Add a Repository property to the SiteWideSettings class
Add a function to the SiteWideSettings class to pass in a repository
Not use a singleton for this at all and just go back to what I was doing before I had this idea
Any comment on this would be greatly appreciated.
Note: I know. I know I'm doing unit testing wrong in this case because I didn't write my test first so please don't scold me for that.. I have already scolded myself and with my next task I won't do it again I promise :)
"Then I had a bright idea. I made a singleton class called
SiteWideSettings and..."
This sounds like a bad idea. Let your database be ground-truth for what the settings are, not some in-memory cache that you now need to keep up to date. Let your ORM do caching if you need it for performance otherwise you are just adding problems especially if you now try to run your site on more than one server.
If you want to simplify the controller so it has less 'set-up' and 'tear-down' code in it, use an IOC (e.g. Autofac) and inject any dependencies you need (e.g. a DataContext or a Repository) on a per-http-request basis.
Your action methods are now easier to test since you can simply instantiate your controller (injecting the dependencies manually using its constructor) and then call your method.
I have started working with ASP.NET controls and there appeared a question:
"why events in ASP controls are defined as delegates, and not as methods"?
Because an event must point to the function that it fires somehow and in C# this mechanism is achieved by delegates.
In response to the comment:
Then, why is such not a case with Java that uses only methods to fire
events?
Because Java uses the old traditional event pattern (like in C++). C# delegates are easier to use and also allow you to point to a static function rather than forcing the use of a class method.