given the following classes:
class SomeBuilder<T>
{
public static object Build(int index)
{
...
}
}
class SomeHelper
{
public object GetBuildObj(object value)
{
var valuetype = value.GetType();
var methodinfo = typeof(SomeBuilder<>).MakeGenericType(valuetype).GetMethod("Build");
var handler = SomeDynamicHelper.GetMethodInvoker(methodinfo);
var result = hander(null, new object[]{1});
}
}
SomeBuilder was a generic type so i need a call to MakeGenericType() to make things right.
when i pass a normal type like 'class person' for the value, everything just works, that`s fine.
but when i pass a anonymous type like: new { id=1 }, the handler was successfully created. but invoke this dynamic handler i got a MethodAccessException with these messages:
"method "SomeDynamicHelper.(System.Object, System.Objec[])" try to access method "SomeBuilder'1<<>f__AnonymousType0'1<System.Int32>>.Build(int)" failed.
any help would be appreciated, thx.
btw, if you are interested in SomeDynamicHelper, plz see:
http://www.codeproject.com/Articles/14593/A-General-Fast-Method-Invoker
edit1:
i did the call in main like this:
static void Main(string[] args)
{
// pass a normal class, this will be fine
var value = new Person { id = 1};
new SomeHelper().GetBuildObj(value);
// pass a anonymous type
var value = new { id = 1};
new SomeHelper().GetBuildObj(value); // oops, got a exception here!
}
edit2:
based on the comment i changed my code:
class SomeHelper
{
public object GetBuildObj(object value)
{
//this time i do not use the value, but create a new inner value:
var valuenew = new { id = 1 };
var valuetype = valuenew.GetType();
var methodinfo = typeof(SomeBuilder<>).MakeGenericType(valuetype).GetMethod("Build");
var handler = SomeDynamicHelper.GetMethodInvoker(methodinfo);
var result = hander(null, new object[]{1});
}
}
well, this time there is no exception, but...unfortunately a new problem occured...may be i should open a new thread for the new problem.
thank you guys, for your attentions.
edit3:
hi, after some digging, i also found some useful information. say, the SomeDynamicHelper.GetMethodInvoker() code as below:
DynamicMethod dynamicMethod = new DynamicMethod(string.Empty, typeof(object), new Type[] { typeof(object), typeof(object[]) }, methodInfo.DeclaringType.Module);
this is the core we used here to dynamic create a method. for our context, we need to declare the anonymous type in same assembly with the SomeHelper and SomeBuilder. but, if we can`t do the declaration, what should we do?
ok, you can call DynamicMethod() with last parameter(the skipVisibility), set to true!
hope this will help others with the same problem :)
"method "SomeDynamicHelper.(System.Object, System.Objec[])" try to access method "SomeBuilder'1<<>f__AnonymousType0'1>.Build(int)"
From this you can see that dynamic method try to run an internal\private method called Build, for that you got MethodAccessException.
(The anonymous type is kept in a new generated class)
Adding InternalVisibleTo not always helping because it's helping only if you can rewrite the anonymous type assembly (manually or with interception) and only if the type and method are internals and not private.
In dynamic method you can bind the method to type\module, and to skip visibility check, but this help to access private members of the specified module, so again if the type you trying to access is in a different assembly and the type\method are private you can't do anything.
Well almost. There is a "secret" attribute that you inject to your assembly, called IgnoreAccessChecksTo and then in addition to bounded module and skip visibility maybe it will work.
You can try using [assembly: InternalsVisibleTo("Anonymously Hosted DynamicMethods Assembly")] in the same project where you define the anonymous type.
I had a similar error with a C# class I tried to inject using IKVM-converted Guice. The fix was simply making the affected class (in this case probably SomeBuilder) public and everything worked fine.
Related
I have the following code
Driver Code
var provider = DataManager.BuildDatabase<FileDatabase>(config,false,dbPath).Result;
DataManager.cs
public static async Task<IStorageProvider> BuildDatabase<TStorageProvider>(DbConfig config,
bool isBuildUniqueAddress = false,params object[] buildParam) where TStorageProvider : IStorageProvider
{
var t = typeof(TStorageProvider);
//merging params
var buildConfig= new DbData(config);
buildParam= buildParam.ToList().Prepend(buildConfig).ToArray();
Console.WriteLine($"Building Database of type:{t.FullName}");
IStorageProvider? storageProvider = (IStorageProvider?)Activator.CreateInstance(t,buildParam);
}
and Here is my Constructor for type FileDatabase
FileDatabase.cs
public FileDatabase(DbConfig config,string dbPath)
{
_dbData = new DbData(config);
DbPath=dbPath;
if (!File.Exists(dbPath))
{
Flush().RunSynchronously();
}
}
When I try to execute code above, it gives me:
MissingMethodException: Constructor on type 'assertUpdaterRefactor.StorageProvider.FileDatabase' not found.\
I tried to debug content of variable buildParam
.
The debugger shows the buildParam is an object array and exactly matches the constructor. I just can't figure out the reason causing this problem. Please help
UPDATE:
When I tried to create a new object array. The issue fixed magically
IStorageProvider? storageProvider = (IStorageProvider?)Activator.CreateInstance(t, new object[]{config,"someStringValue"});
Here is the original code copied from above just for reference
IStorageProvider? storageProvider = (IStorageProvider?)Activator.CreateInstance(t,buildParam);
I want to know the causes and why the original code does not work.
The first argument of the FileDatabase is DbConfig, in your BuildDatabase you use a type DbData.
So instead of passing an instance of var buildConfig= new DbData(config); pass the config directly.
Would be something like:
public static async Task<IStorageProvider> BuildDatabase<TStorageProvider>(DbConfig config,
bool isBuildUniqueAddress = false,params object[] buildParam) where TStorageProvider : IStorageProvider
{
var t = typeof(TStorageProvider);
//merging params
buildParam= buildParam.ToList().Prepend(config).ToArray();
Console.WriteLine($"Building Database of type:{t.FullName}");
IStorageProvider? storageProvider = (IStorageProvider?)Activator.CreateInstance(t,buildParam);
}
I want to make a deep Copy for my Class TreeNode. Here is my code:
public TreeNode(TreeNode node, GUIStyle inPointStyle, GUIStyle outPointStyle, Action<ConnectionPoint> OnClickInPoint, Action<ConnectionPoint> OnClickOutPoint)
{
this.rect = new Rect(node.rect);
this.style = new GUIStyle(node.style);
this.inPoint = new ConnectionPoint(this, ConnectionPointType.In, inPointStyle, OnClickInPoint);
this.outPoint = new ConnectionPoint(this, ConnectionPointType.Out, outPointStyle, OnClickOutPoint);
this.defaultNodeStyle = new GUIStyle(node.defaultNodeStyle);
this.selectedNodeStyle = new GUIStyle(node.selectedNodeStyle);
this.allDecorations = new List<GameObject>(node.allDecorations);
this.objs = new Dictionary<GameObject, IndividualSettings>(node.objs);
this.name = String.Copy(node.name);
this.RemoveClonedObj = new Action(node.RemoveClonedObj);
this.OnChangeView = new Action<TreeNode>(node.OnChangeView);
this.OnRemoveNode = new Action<TreeNode>(node.OnRemoveNode);
this.OnCopyNode = new Action<TreeNode>(node.OnCopyNode);
this.PreviewTree = new Action<TreeNode, bool> (node.PreviewTree);
}
However, the Rider gave me the warning:
It seems the Rider was saying that my "new" is meaningless.
If I follow Rider's instruction, usethis.RemoveClonedObj = node.RemoveClonedObj; what will happen for my copyed TreeNode's Actions aftering removing the orginal TreeNode? Will they be removed as well? If so, why does Rider give me such warning?
In C# 2.0 or above, the following codes are equivalent (DelegateType is a delegate type, as its name suggests):
newDelegate = new DelegateType(oldDelegate);
newDelegate = oldDelegate;
(See MSDN - How to: Declare, Instantiate, and Use a Delegate (C# Programming Guide))
Also, Microsoft specifies (see here) that such operation will always create a new instance of DelegateType, which has the same invocation list as the oldDelegate. They do not refer to the same object (don't be confused by the = assignment):
The binding-time processing of a delegate_creation_expression of the form new D(E), where D is a delegate_type and E is an expression, consists of the following steps:
If E is a method group, the delegate creation expression is processed in the same way as a method group conversion (Method group conversions) from E to D.
If E is an anonymous function, the delegate creation expression is processed in the same way as an anonymous function conversion (Anonymous function conversions) from E to D.
If E is a value, E must be compatible (Delegate declarations) with D, and the result is a reference to a newly created delegate of type D that refers to the same invocation list as E. If E is not compatible with D, a compile-time error occurs.
So regarding your question
What will happen for my copyed TreeNode's Actions aftering removing the orginal TreeNode? Will they be removed as well?
Nothing will happen to them. They will not be removed.
By the way, since you are trying to make a deep copy of your tree-node, I suspect whether it is the correct way. Though you have created a new instance of your delegate, the class instance associated with it (the instance on which member methods will be invoked) stays the same.
Do not link instance methods to each other. This will lead to memory leaks.
Even after the original node is removed and no longer needed by your code, due to the reference from the copy the original instance will live in the memory and not be garbage collected.
I suspect this is not what you want, Test code for this
class Program
{
static void Main(string[] args)
{
First t = new First();
Second s = new Second();
t.Print = s.TestMethod;
s.test = "change";
s = null;
t.Print("Hell"); // can debug and see that the function call goes through and string test is = "change"
}
}
public class First
{
public string s;
public Action<string> Print;
}
public class Second
{
public string test = "created";
public void TestMethod (string test)
{
var res = "hello" + test + test;
}
}
Either your methods on the node should be part of the Node object, this way you do not have to assign them to new nodes, or they should be in a separate class, preferably static, so that creation of new nodes does not lead to a memory issue.
I imported the taglib-sharp dll (that had been copied to the bin/debug folder of my project) in my C# application and then used types and methods from the library in the following way:
using TagLib;
private void method()
{
TagLib.File file = TagLib.File.Create("C:\\temp\\some.mp3");
TagLib.Tag tag = file.GetTag(TagLib.TagTypes.Id3v2);
}
Now I want to link the dll dynamically. How can I implement the same functional in this case?
That, what I've tried:
using System.Reflection
private void method()
{
Assembly TagLib = Assembly.Load("taglib-sharp");
Type TagLibFile = TagLib.GetType("File");
dynamic LibFile = Activator.CreateInstance(TagLibFile);
TagLibFile file = LibFile.Create("c:\\temp\\some.mp3");
}
In this implementation, VisualStudio says that I can't use the tagLibFile variable as a type. I supposed that when I get a type from dll, I will be able to create variables of this type.
By the way, is this approach is correct?
P.S. Also, I tried to use the invoke method, but I was not sure what object I should pass as a first argument.
UPD
Based on #nawfal's awnser below, I've got the following working code:
using System.Reflection
private void method()
{
Assembly TagLib = Assembly.Load("taglib-sharp");
// get the File type
var fileType = TagLib.GetType("TagLib.File");
// get the overloaded File.Create method
var createMethod = fileType.GetMethod("Create", new[] { typeof(string) });
// get the TagTypes method that contains Id3v2 field
Type tagTypes = TagLib.GetType("TagLib.TagTypes");
// get the overloaded File.GetTag method
var getTagMethod = fileType.GetMethod("GetTag", new[] {tagTypes});
// obtain the file
dynamic file = createMethod.Invoke(null, new[] { "C:\\temp\\some.mp3" });
// obtain the Id3v2 field value
FieldInfo Id3TagField = tagTypes.GetField("Id3v2");
var Id3Tag = Id3TagField.GetValue(tagTypes);
// obtain the actual tag of the file
var tag = getTagMethod.Invoke(file, new[] { Id3Tag });
}
You should be doing something like this:
private void method()
{
var assembly = Assembly.Load("taglib");
var type = assembly.GetType("namespace.File"); // namespace qualified class name
// assuming you only have one Create method, otherwise use reflection to resolve overloads
var method = type.GetMethod("Create");
dynamic file = method.Invoke(null, new[] { "C:\\temp\\some.mp3" }); // null for static methods
var tag = file.GetTag(TagLib.TagTypes.Id3v2); // not sure if you can pass those params,
// may be do reflection to get them too
}
Kindly rethink if you want it to be dynamic. If you can reference the dll then you can still get the benefits of strong typing.
Save it as object.
object file = LibFile.Create(fi.FullName);
Should work.
Dynamic loading dlls works much different.
I was looking at the question Use 'dynamic' throw a RuntimeBinderException. I face a similar problem:
Basically, I want to create a "HTML helper" in ASP.NET MVC that uses dynamic arguments, akin to the htmlArguments parameter for many of the existing helpers (more code below):
public BootstrapCell(Action<string> emitContentAction, dynamic args)
View:
#using (grid.Cell(ViewContext.Writer.Write, new {Position = 4}))
{
<p>zomg!</p>
}
However in the naive approach, i get RuntimeBinderException thrown at me, declaring that 'object' does not contain a definition for 'Position', even though when debugging and hovering over the _args variable, it clearly does have a Position property.
The caller and the callee are in separate assemblies. Why is that problem happening?
(The solution to that has been shown in the same question: Manually create an ExpandoObject to hold the args.)
Implementation:
public class Cell
{
private readonly string _tagName;
private dynamic _args;
private Action<string> EmitContentAction;
public BootstrapCell(Action<string> emitContentAction, dynamic args) : DisposableBaseClass
{
_args = args;
EmitContentAction = emitContentAction;
OnContextEnter();
}
protected void OnContextEnter()
{
var sb = new StringBuilder("<");
sb.Append(_tagName);
if (_args.Position > 0)
{
sb.Append(" class=\"offset");
sb.Append(args.Position);
sb.Append("\"");
}
sb.Append(">");
EmitContentAction(sb.ToString());
}
}
[Edited to make clearer that my problem arises when "obviously" the Position property is set. I am aware that if the property never was defined in the first place, an exception must be raised.]
That code is fatally flawed.
It does work, as long as you specify that property:
void Bar()
{
Foo(new {Position = 0});
}
void Foo(dynamic args)
{
Console.WriteLine(args.Position);
}
That will output 0, it will not throw a RuntimeBinderException.
But the purpose of such code is the possibility for the caller to specify only the properties needed and omit the rest.
You are trying to check for this omission via if(args.Position != null). But that doesn't work, it already requires Position to exist.
When you have a look at the routing API of ASP.NET that also supports those anonymous configuration objects you will notice that the type of the parameter is object and not dynamic.
Using object instead of dynamic will enable your API to be used across assembly boundaries.
So how does it work?
Just like in the linked answer, you need to manually create a dictionary of the properties. Whether you use a plain old Dictionary<string, object> or an ExpandoObject is a matter of preference.
Using ExpandoObject will make your code a bit simpler to read and write, but it is not required.
About the actual exception you are getting:
Please note that it tells you it can't find the Position property on object. If it would be an anonymous type that was missing the Position property the exception message wouldn't refer to object but to an anonymous type. Something like this:
'<>f__AnonymousType0' does not contain a definition for 'Position'
I have a class which has the following constructor
public DelayCompositeDesigner(DelayComposite CompositeObject)
{
InitializeComponent();
compositeObject = CompositeObject;
}
along with a default constructor with no parameters.
Next I'm trying to create an instance, but it only works without parameters:
var designer = Activator.CreateInstance(designerAttribute.Designer);
This works just fine, but if I want to pass parameters it does not:
var designer = Activator.CreateInstance(designerAttribute.Designer, new DelayComposite(4));
This results in an MissingMethodException:
Constructor voor type
Vialis.LightLink.Controller.Scenarios.Composites.DelayCompositeDesigner
was not found
Any ideas here?
The problem is I really need to pass an object during construction.
You see I have a designer which loads all the types that inherit from the CompositeBase. These are then added to a list from which the users can drag them to a designer. Upon doing so an instance of the dragged is added to the designer. Each of these classes have custom properties defined on them:
[CompositeMetaData("Delay","Sets the delay between commands",1)]
[CompositeDesigner(typeof(DelayCompositeDesigner))]
public class DelayComposite : CompositeBase
{
}
When the user selects an item in the designer, it looks at these attributes in order to load up a designer for that type. For example, in the case of the DelayComposite it would load up a user control which has a label and a slider which allow the user to set the "Delay" property of the DelayComposite instance.
So far this works fine if I don't pass any parameters to the constructor. The designer creates an instance of the DelayCompositeDesigner and assigns it to the content property of a WPF ContentPresenter.
But since that designer needs to modify the properties of the selected DelayComposite
in the designer, I have to pass this instance to it. That is why the constructor looks lie this:
public DelayCompositeDesigner(DelayComposite CompositeObject)
{
InitializeComponent();
compositeObject = CompositeObject;
}
Suggestions are welcome
#VolkerK
The result of your code is this:
<---- foo
Vialis.LightLink.Controller.Scenarios.Composites.DelayCompositeDesignerVoid
.ctor()
Vialis.LightLink.Controller.Scenarios.Composites.DelayCompositeDesignerVoid
.ctor(Vialis.LightLink.Controller.Scenarios.Composites.DelayComposite)
param:Vialis.LightLink.Controller.Scenarios.Composites.DelayComposite
foo ---->
Leppie, you were correct, I had for some reason referenced the Composites assembly in my UI application... which is not something I should have done as I was loading it at runtime. The following code works:
object composite = Activator.CreateInstance(item.CompositType,(byte)205);
var designer = Activator.CreateInstance(designerAttribute.Designer, composite);
As you can see the code does not have knowledge of the DelayComposite type.
This solves the current problem, but introduces many new ones for what I want to achieve,
either way thank you and thank you to everyone who has replied here.
As for the following code, suggested by multiple people:
var designer = Activator.CreateInstance(
designerAttribute.Designer,
new object[] { new DelayComposite(4) }
);
The Activator.CreateInstance has a signature that looks like this:
Activator.CreateInstance(Type type, params object[] obj)
So it should accept my code, but I will try the suggested code
UPDATE:
I've tried this as suggested:
var designer = Activator.CreateInstance(designerAttribute.Designer, new object[] { new DelayComposite(4)});
The result is the same.
I would think that your call would need to be:
var designer = Activator.CreateInstance(designerAttribute.Designer, new object[] { new DelayComposite(4) });
Unless, of course, it is that, in which case the answer is not immediately obvious.
I think you are dealing with a Type mismatch.
Likely the assembly is referenced in different places, or they are compiled against different versions.
I suggest you iterate through the ConstructorInfo's and do a paramtype == typeof(DelayComposite) on the appropriate parameter.
Though I hate printf-like debugging ...
public static void foo(Type t, params object[] p)
{
System.Diagnostics.Debug.WriteLine("<---- foo");
foreach(System.Reflection.ConstructorInfo ci in t.GetConstructors())
{
System.Diagnostics.Debug.WriteLine(t.FullName + ci.ToString());
}
foreach (object o in p)
{
System.Diagnostics.Debug.WriteLine("param:" + o.GetType().FullName);
}
System.Diagnostics.Debug.WriteLine("foo ---->");
}
// ...
foo(designerAttribute.Designer, new DelayComposite(4));
var designer = Activator.CreateInstance(designerAttribute.Designer, new DelayComposite(4));
What does that print in the visual studio's output window?
If you want to call this contructor...
public DelayCompositeDesigner(DelayComposite CompositeObject)
...just use this:
var designer = Activator.CreateInstance(typeof(DelayCompositeDesigner), new DelayComposite(4));
or
var designer = Activator.CreateInstance<DelayCompositeDesigner>(new DelayComposite(4));
I had a similar issue, however my problem was due to the visibility of the constructor. This stack overflow helped me:
Instantiating a constructor with parameters in an internal class with reflection
I discovered another way of creating an instance of an object without calling the constructor at all while answering another question on SF.
In the System.Runtime.Serialization namespace there is a function FormatterServices.GetUninitializedObject(type) that will create an object without calling constructor.
If you look at that function in Reflector you will see it is making an external call. I don't know how black magic is actually happening under the hood. But I did prove to myself that the constructor was never called but the object was instantiated.
When I encountered this problem, I was using a method that returned the parameter list to plug in to Activator.CreateInstance and it had a different number of arguments than the constructor of the object I was trying to create.
In my case, this code work good with .NET Framework but does not work in .NET Core 3.1. It throws ExecutionEngineException which is uncatchable. But when I change target to .NET 5, it works perfectly. Hope this help some one.
Type type = assembly.GetType(dllName + ".dll");
Activator.CreateInstance(type ), new Stream[] { stream };
You can use the following overload on CreateInstance:
public static Object CreateInstance(
Type type,
Object[] args
)
And in your case it'd be (I think):
var designer = Activator.CreateInstance(
typeof(DelayCompositeDesigner),
new object[] { new DelayComposite(4) }
);
I found a solution to the problem, I was struggling with the same issue.
Here is my activator:
private void LoadTask(FileInfo dll)
{
Assembly assembly = Assembly.LoadFrom(dll.FullName);
foreach (Type type in assembly.GetTypes())
{
var hasInterface = type.GetInterface("ITask") != null;
if (type.IsClass && hasInterface)
{
var instance = Activator.CreateInstance(type, _proxy, _context);
_tasks.Add(type.Name, (ITask)instance);
}
}
}
And here is my class to activate, note that I had to change the constructor params to objects, the only way I could get it to work.
public class CalculateDowntimeTask : Task<CalculateDowntimeTask>
{
public CalculateDowntimeTask(object proxy, object context) :
base((TaskServiceClient)proxy, (TaskDataDataContext)context) { }
public override void Execute()
{
LogMessage(new TaskMessage() { Message = "Testing" });
BroadcastMessage(new TaskMessage() { Message = "Testing" });
}
}