When I'm using VB.NET to use subsonic, It seems to have problem marking records as Old and Clean. Whenever I query using ExecuteSingle or ExecuteTypedList, i need to manually MarkClean and MarkOld, else whenever I save it will save as a new record.
Am I the only one facing this problem ? I'm using SubSonic 2.2 btw.
I checked the source code of SubSonic.. and I found that the VB class generator doesn't implements the IActiveRecord. I think most likely is because VB.Net doesn't seem to support 're-implementation' of inheritance or whatever you call that...
So when I debug, I found that Utility.IsSubSonicType returns false (because the ActiveRecord class returns as IReadOnlyRecord, but IsSubSonicType checks for IActiveRecord and IRecordBase) and thus doesn't call the SetLoadState and MarkClean.
So I'm not sure if this is a bug or it is intentional. Any way to solve this?
When you use ExecuteSingle or ExecuteTypedList, you could be doing with a class that didnt have those properties, I think the intention is that you are populating a POCO and not (necessarily) an Entity or other ORM object.
ExecuteAsCollection and all of the .Load methods behave as you expect because they call SetLoadState() and/or MarkClean().
Personally, I dont face this problem because I use Subsonic purely as a (smart) DAL (CRUD Only) and my own entity layer takes care of things like dirty/new.
Yes, I had the same problem. MarkClean and MarkOld before setting properties and saving fixed the issue. see this
Related
I have one VB6 ActiveX DLL that exposes a class INewReport. I added some new methods to this class and I was able to rebuild it and keep binary compatibility.
I have a second DLL that exposes a class clsNewReport, which implements the first class using:
Implements RSInterfaces.INewReport
Since I added new methods to INewReport, I had to also add those new methods to clsNewReport.
However, when I try to compile the second DLL, I get the binary-compatibility error "...class implemented an interface in the version-compatible component, but not in the current project".
I'm not sure what is happening here. Since I'm only adding to the class, why can't I maintain binary compatibility with the second DLL? Is there any way around this?
I think this is a correct explanation of what is happening, and some potential workarounds.
I made up a test case which reproduced the problem in the description and then dumped the IDL using OLEView from the old & new DLL which contained the interface.
Here is a diff of the old (left) and new IDL from INewReport:
Important differences:
The UUID of interface _INewReport has changed
A typedef called INewReport___v0 has been added which refers to the original UUID of the interface
(I assume that this is also what is happening to the code referred to in the question.)
So now in the client project the bincomp DLL refers to the original interface UUID; but that UUID only matches against a different name (INewReport___v0 instead of INewReport) than it did originally. I think this is the reason VB6 thinks there is a bincomp mismatch.
How to fix this problem? I've not been able to do anything in VB6 that would allow you to use the updated interface DLL with the client code without having to break bincomp of the client code.
A (bad) option could be to just change the client DLL to use project compatibility... but that may or may not be acceptable in your circumstances. It could cause whatever uses the client DLL to break unless all the consumers were also recompiled. (And this could potentially cause a cascade of broken bincomp).
A better but more complex option would be to define the interface in IDL itself, use the MIDL compiler to generate a typelib (TLB file), and reference that directly. Then you would have full control over the interface naming, etc. You could use the IDL generated from OLEView as a starting point for doing this.
This second option assumes that the interface class is really truly an interface only and has no functional code in it.
Here's how I setup a case to reproduce this:
Step 1. Original interface definition - class called INewReport set to binary compatible:
Sub ProcA()
End Sub
Sub ProcB()
End Sub
Step 2. Create a test client DLL which implements INewReport, also set to binary compatible:
Implements INewReport
Sub INewReport_ProcA()
End Sub
Sub INewReport_ProcB()
End Sub
Step 3: Add ProcC to INewReport and recompile (which also registers the newly built DLL):
(above code, plus:)
Sub ProcC()
End Sub
Step 4: Try to run or compile the test client DLL - instantly get the OP's error. No need to change any references or anything at all.
I was able to recreate your problem, using something similar to DaveInCaz's code. I tried a number of things to fix it, probably repeating things you've already tried. I came up with a possible hypothesis as to why this is happening. It doesn't fix the problem, but it may throw some additional light on it.
Quoting from This doc page:
To ensure compatibility, Visual Basic places certain restrictions on changes you make to default interfaces. Visual Basic allows you to add new classes, and to enhance the default interface of any existing class by adding properties and methods. Removing classes, properties, or methods, or changing the arguments of existing properties or methods, will cause Visual Basic to issue incompatibility warnings.
Another quote:
The ActiveX rule you must follow to ensure compatibility with multiple interfaces is simple: once an interface is in use, it can never be changed. The interface ID of a standard interface is fixed by the type library that defines the interface.
So, here's a hypothesis. The first quote mentions the default interface, which suggests that it may not be possible to alter custom interfaces in any way. That's suggested by the second quote as well. You're able to alter the interface class, because you are essentially altering its default interface. However, when you attempt to alter the implementing class in kind, to reflect the changes in your interface, your implementation reference is pointing to the older version of the interface, which no longer exists. Of course, the error message doesn't hint at this at all, because it appears to be based on the idea that you didn't attempt to implement the interface.
I haven't been able to prove this, but looking at DaveInCaz's answer, the fact that the UUID has changed seems to bear this idea out.
Is something like this possible? If so, could you point me in the right direction for learning how?
applicationx tries to run the method start() in dll_one.dll
dll_one.dll runs the command
applicationx tries to run the method run() in dll_one.dll
dll_one.dll doesn't have a method run() and hasn't prepared for such an occurance.
dll_one.dll asks dll_two.dll if it has a run()
dll_two runs run()
Basically, I want it so if dllA doesn't have a method that the application is looking for, it asks dllB. This is assuming, as well, that ApplicationX and dllB don't know anything about dllA and dllA kind of just appeared out of nowhere (I want dlls dynamically like a patch to my applications without having to rewrite ALL of the methods, properties, etc. in the dll and have everything else just routed to the old dll).
Any ideas? Keep in mind, I'm using vb.net so a .net reference is appreciated.
It seems like you're asking for a plug-in architecture for your app (except that "patch" part is bothering me). If so, you can try MEF, which solves this exact problem.
The specific thing you ask for isn't possible. You can't have a non-existent method call automatically re-routed to a different dll. You can't "run the method run() in dll_one.dll" unless you've compiled that code, and it won't compile if the method doesn't exist. You also can't compile code against dllB and then drop dllA in and have it intercept method calls. Reflection could conceivably solve part of your problem, but you'd not want to base your code around calling all methods by reflection - it'd be horrendously unperformant and not very maintainable.
As Anton suggests, a plugin approach might work. However, this would rely on you being able to specify up-front the interface for your plugin, which sounds like it would contradict your original requirement.
Another problem: if you'd not deployed dllA until later, how would your ApplicationX know to call method start() in dll_one.dll anyway? You'd surely need to re-deploy at least the base application for that part to work.
These kinds of problem are often best solved by having a more specific set of requirements to work to: what functionality are you likely to want to extend or change in the future? Could you support a common set of interfaces that allow extensibility via plugins, or can you need to redeploy encapsulated chunks of your application with new functionality? Is there UI involved or is this just to change back-end logic? Questions like this could help to suggest more viable solutions.
I'm about to start translating my vb.net application, and I don't want to use the default methods provided by Visual Studio to do so. I need my application to be very light, and it nearly doubles it size to use the resources option.
Therefore, I'm planning to use some thing like a class, of which I would have one instance per language. Since I don't want to distribute language files as separate files (I'd rather have them hard-coded), I would like to find an easy way to check if every field of the class is initialized. I was thinking of something like an Interface, where I would do something like this:
Public Interface Language
Dim HelloMsg As String
Dim GoodbyeMsg As String
End Interface
Public class English Implements Language
HelloMsg = "Hello!"
GoodbyeMsg = "Goodbye!"
End Class
It's obviously not the right way to do it (although I could use properties instead of vars), but I was wondering whether the was a way to have the compiler check that everything is translated and warn about it if not.
Anyway, maybe is there a much better way to handle this problem ?
Thanks a lot!
CFP.
I'm not convinced that you should dump the resource-based localization approach just because your app has grown in size. Indeed, it could've grown from 100 Kb to 200 Kb, but this is it! It won't grow this much more. And 200 Kb is nothing nowadays.
So my advice is to reconsider and go resource-based route.
I've decided to use a singleton class that loads a translation file, with a method that loops through all items on a form and translate on-the-fly. See Create Synchronicity source code for more details (more specifically TranslateControl in this code file)
Do you have a naming convention for APIs or Classes that are being phased in to replace an older version that performed the same function / filled the same role?
E.g. Windows does this by adding "Ex" to the end of the function:
ShellExecute // old
ShellExecuteEx // new
What do you prefer, and what are you reasonings?
Appending 2, V2, New, NowInStereo?
Doing a one-time rename of the old API from Something to SomethingOld and using Something for the new stuff? This option worries me when it comes to version control, but it also seems the least likely to be burdened with a V3 or ReallyNew problem in the future.
Making up a completely different name that may describe the function less accurately, but at least is different.
Much of the time you can get away with changing the package name, rather than the class name itself.
If the new class performs the same function as the old one, I remove the old one and replace it with the new one with same name. I can still consult the old one in version control if needed.
Why change it at all? Interfaces being the contracts that they are, why would you break the interface after everything is using it.
Edit: Sorry to botch your comment Josh...
I think that if you've gone to the trouble to create the interface you need to do everything you can to maintain it. What kind of bad choice were you thinking about when you commented before?
You only need to create a new function if the arguments to the function are changed due to new requirements for the function.
The best naming convention for an API is the one the users of the API would expect. If the API is used only on Windows then adding an Ex (or Ex2 for the next rev) may be appropriate. I'm not aware of other conventions on other platforms. Also, your programming language may have a convention for extending API methods.
If you are using an object oriented language and this is an object method, you do not have to change the name because you can have methods with the same name and different signatures. However, it may still make sense to provide a new name to let users know that you want them to migrate to the new method.
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.