I want to know clearly why and when we use seam injection and outjection? I find and research all day but i can't clearly see it.Please help me.I will appreciate all of your supports.We can import bean and call it properties and methods.That's right?what's the difference?
They means injection like that
#In
Specifies that a component attribute is to be injected from a context variable at the beginning of each component invocation. If the context variable is null, an exception will be thrown.
Make sure you understand Depedency Injection as a concept first. Then get a copy of Seam in Action. Your chapter of choice is chapter 6.
I'm sorry the question really is far too general to give a conclusion about the concepts.
Related
I created a new custom Block and wanted to inject an IOptionsSnapshot to read my appsettings.json values. The problem is that I get an error saying there is no parameterless constructor for my custom block.
Is there a way to somehow do this injection or is this a limitation in Piranha and custom blocks.
At the moment neither Fields nor Blocks supports parameter injection into the constructor, however Fields have two initialization methods that both support parameter injection, Init() and InitManager(). Given how models are constructed the easiest solution would probably be to add the corresponding init methods to Blocks as well.
Feel free to open an issue/feature request at the GitHub repo and we can take the discussion from there!
I am using MethodCall.setsField() to try to set an instance field on another instance.
My generated class that is doing the field-setting, GC, is trying to set the value of an instance field in an instance of something it has created (CI). So the field's declaring type is CI; my field-setting code resides in GC (which is in the same package as CI but otherwise unrelated to it).
The ByteBuddy checks seem to indicate that although GC and CI are in the same package, GC must be assignable to CI in order to set this field! That greatly surprised me, but I am not a bytecode expert, and I might very well be overlooking something obvious. Could someone kindly explain why this check is necessary?
The method call sets the field implicitly on the this instance on which the method is invoked. For this to be possible, a non-static field must be declared by a super type of the type on which the method is invoked.
If you think this is too strict, please file an issue with an example of the code you are trying to generate, including the code to generate it which is currently failing. Maybe I am not thinking straight about this and if there's a restriction to be lifted, I would surely do it.
We are finding issues (and reporting them) in EclipseLink's InformixPlatform class--the class responsible for adapting the Informix database to the requirements of the EclipseLink innards.
We have a couple of type conversion issues. For example, Informix supports two opaque literals (t and f--not the characters, but actual literals) as native boolean values. It appears that perhaps EclipseLink is trying to use SMALLINT instead as the database type.
Short of a lot of procedural code inside a SessionCustomizer, I cannot find a good place to correct or improve such global conversion behavior.
Where is the best place to register this global take-a-value-from-the-database-and-convert-it-to-a-Java-object behavior? Other questions seem to indicate that this is impossible, but I find that very hard to believe.
Build your own conversion manager class (extend org.eclipse.persistence.internal.helper.ConversionManager).
and override the method convertObjectToBoolean().
To enable the usage of your own conversion manager instance in eclipselink, use a SessionCustomizer and invoke session.getPlatform().setConversionManager()
However, when looking at the source code of this method it seems that the support of the t and f literals is already implemented (at least in eclipselink 2.3.3). But maybe there's a bug?
It's may be worth debugging this method while your application is running to really see what's going on there.
I've been (happily) using Ninject for a while now with some basic scenarios, and would like to give it control of my logging. I noted the existence of the Ninject.Extensions.Logging namespace, and would like to use it, but I'm running into two issues:
I want the logger to be initialized with the type of the class running it (as if I ran LogManager.GetLogger with the GetCurrentMethod().DeclaringType).
I want to be able to easily mock, or "nullify" the logger for unit testing (i.e I don't want to have the logger work), without running into NullReferenceExceptions for not initializing the logger.
Now, I know there are some questions (and even answers) around here, but I couldn't seem to find any that pointed me in the right direction.
I'll appreciate any help (even a "you bone-head" it's here! Linking to something I should have noticed).
This is the default behavior of the extension
Don't use Ninject to create the object under test in your unit tests. Create an instance manually and pass what ever you want for the logger.
Best you have a look at the unittests. https://github.com/ninject/ninject.extensions.logging/blob/master/src/Ninject.Extensions.Logging.Tests/Infrastructure/CommonTests.cs
To implement "method-missing"-semantics and such in C# 4.0, you have to implement IDynamicObject:
public interface IDynamicObject
{
MetaObject GetMetaObject(Expression parameter);
}
As far as I can figure out IDynamicObject is actually part of the DLR, so it is not new. But I have not been able to find much documentation on it.
There are some very simple example implementations out there (f.x. here and here), but could anyone point me to more complete implementations or some real documentation?
Especially, how exactly are you supposed to handle the "parameter"-parameter?
The short answer is that the MetaObject is what's responsible for actually generating the code that will be run at the call site. The mechanism that it uses for this is LINQ expression trees, which have been enhanced in the DLR. So instead of starting with an object, it starts with an expression that represents the object, and ultimately it's going to need to return an expression tree that describes the action to be taken.
When playing with this, please remember that the version of System.Core in the CTP was taken from a snapshot at the end of August. It doesn't correspond very cleanly to any particular beta of IronPython. A number of changes have been made to the DLR since then.
Also, for compatibility with the CLR v2 System.Core, releases of IronPython starting with either beta 4 or beta 5 now rename everything in that's in the System namespace to be in the Microsoft namespace instead.
If you want an end to end sample including source code, resulting in a dynamic object that stores value for arbitrary properties in a Dictionary then my post "A first look at Duck Typing in C# 4.0" could be right for you. I wrote that post to show how dynamic object can be cast to statically typed interfaces. It has a complete working implementation of a Duck that is a IDynamicObject and may acts like a IQuack.
If you need more information contact me on my blog and I will help you along, as good as I can.
I just blogged about how to do this here:
http://mikehadlow.blogspot.com/2008/10/dynamic-dispatch-in-c-40.html
Here is what I have figured out so far:
The Dynamic Language Runtime is currently maintained as part of the IronPython project. So that is the best place to go for information.
The easiest way to implement a class supporting IDynamicObject seems to be to derive from Microsoft.Scripting.Actions.Dynamic and override the relevant methods, for instance the Call-method to implement function call semantics. It looks like Microsoft.Scripting.Actions.Dynamic hasn't been included in the CTP, but the one from IronPython 2.0 looks like it will work.
I am still unclear on the exact meaning of the "parameter"-parameter, but it seems to provide context for the binding of the dynamic-object.
This presentation also provides a lot of information about the DLR:
Deep Dive: Dynamic Languages in Microsoft .NET by Jim Hugunin.