I has interface
public interface ITest
{
Task<bool> MyMethod1<T>(string key, out T value);
Task<bool> MyMethod2<T>(string key, out T value);
}
And they implementation
public class TestImpl : ITest
{
public Task<bool> MyMethod1<T>(string key, out T value) // Implements interface
{
// Skipped
}
public Task<bool> MyMethod1<T>(string key, T value) // Does not implements interface
{
// Skipped
}
public Task<bool> MyMethod2<T>(string key, out T value) // Implements interface
{
// Skipped
}
public Task<bool> MyMethod2<T>(string key, T value) // Does not implements interface
{
// Skipped
}
}
I need to check that specified instance of MethodInfo is method implementation of ITest interface.
For example:
void DoWork(MethodInfo methodInfo)
{
if (...) // Check methodInfo is implementation of any method declared in ITest interface
{
/* Do something */
}
}
How to do that?
I have an idea, but I don't know if it fits your situation
Why you don't get type of the implementation the class and then you get the interface you are interested in by its name nameof(ITest) and then you iterate through all methods of this interface which is implemented by that type like the following:
foreach(var methodInfo in typeof(TestImpl).GetInterface(nameof(ITest)).GetMethods())
{
}
This is very easy idea, the fact that you didn't hard-coded the interface name in the foreach loop it is good too.
If it didn't fit your situation, please consider adding more details to your question so I can think about a different idea and edit this answer, or someone can help you.
EDIT
Or you can get the concrete class type by the property ReflectedType and then you can get a 'reflection-mapping' of the methods of this type based on specific interface type using GetInterfaceMap method, this method will then returns the methods which is implemented for this interface type in this concrete class type, you can then simply use the method Contains to check for specific MethodInfo instance as you asked. Hope this helped you now.
static bool IsMethodImplementationOfInterface(Type interfaceType,MethodInfo method)
{
return method.ReflectedType.GetInterfaceMap(interfaceType).TargetMethods.Contains(method);
}
foreach (var methodInfo in typeof(TestImpl).GetMethods())
{
if (IsMethodImplementationOfInterface(typeof(ITest), methodInfo))
{
//Logic
}
}
You can use GetInterfaceMap:
var testImpl = new TestImpl();
var interfaceTargeMethods = testImpl.GetType().GetInterfaceMap(typeof(ITest)).TargetMethods;
foreach (var methodInfo in testImpl.GetType().GetMethods())
{
if (interfaceTargeMethods.Contains(methodInfo))
{
// do something...
}
}
Related
example
i have a class
using System;
namespace ConsoleApp1
{
public interface INode<T>
{
T Value { get; }
}
public class A
{
public void Do1(INode<string> node) { }
public void Do2<T>(INode<T> node) { }
}
public class Programm
{
public static void Main(string[] args)
{
A a = new A();
//now I want to pass this method to an another class as arguments
//it's OK here
var processor1 = new Proccessor(a.Do1);
//no idea how to achieve this without making class Proccessor generic type
var processor2 = new Proccessor(a.Do2);
}
}
public class Proccessor
{
//it's OK here
public Proccessor(Action<INode<string>> do1Action)
{
}
//no idea how to achieve this without making class Proccessor generic type
public Proccessor(Action<T><INode<T>> do2Action)
{
}
}
}
It looks like you're trying to pass an Action<T> to a method such that the method can then choose which T to invoke it for. That's simply not possible.
The easiest way around this is avoiding generics entirely, by making all BaseNodeViewModel<T, U> derive from a common non-generic BaseNodeViewModel type. Your OnNodeExpanded then looks like
private void OnNodeExpanded(BaseNodeViewModel node) { ... }
and it may cast node to the concrete type as needed in its implementation.
A more advanced way around this is creating a custom interface type
internal interface INodeExpanded {
void OnNodeExpanded<TNode>(BaseNodeViewModel<TNode, FolderTreeViewModel> node);
}
You can then manually create a class which implements this interface, and pass that to A instead of a delegate.
The answer to this question depends on what exactly you expect to be able to do with do2Action inside the class.
Do you to say "I want to accept and store an action that will be able to work with any INode"? Assuming that's the case, make INode covariant, and demand an Action<INode<object>>. Like so:
public interface INode<out T>
{
T Value { get; }
}
Then...
public Proccessor(Action<INode<object>> do2Action)
{
}
Now you can do:
var processor2 = new Proccessor((Action<INode<object>>)a.Do2(x));
The cast is required to disambiguate from the string overload, but if you remove the overloads and instead use distinctly named static methods to construct, you will find that this is type safe.
Note that an immense responsibility has now been pushed to a.Do2, it must be able to work with any INode whatsoever, without restriction.
You can't have a generic constructor for a non-generic class. You have at least 3 options (Asad's answer is also very good if your intentions are what he specified in his answer):
don't use generics. see hvd's answer.
make the class generic.
don't use T in the constructor, but in another method. You can have a static method that will create and return an instance of the class for you, there you can use the generic action:
public class Proccessor
{
//it's OK here
public Proccessor(Action<INode<string>> do1Action)
{
}
private Proccessor()
{
// a private constructor for the CreateProcessor static method
}
public static Proccessor CreateProccessor<T>(Action<INode<T>> do2Action)
{
var proccessor = new Proccessor();
// invoke action here
}
}
I'm currently have an implementation of Chain of Responsibility which return objects that implement IResponse.
public interface IRequest
{
}
public interface IResponse
{
}
public interface IFactory
{
bool CanHandle(IRequest request);
IResponse HandleRequest(IRequest request);
}
public class Foo : IResponse
{
public void SpecificMethod()
{
Console.WriteLine("SpecificMethod() only belongs to Foo");
}
}
public class FooRequest : IRequest
{
}
public class FooFactory : IFactory
{
public bool CanHandle(IRequest request)
{
return request is FooRequest;
}
public IResponse HandleRequest(IRequest request)
{
return new Foo();
}
}
public class FactoryManager
{
private readonly List<IFactory> _factoryImplementations = new List<IFactory>();
public void Register(IFactory factory)
{
_factoryImplementations.Add(factory);
}
public IResponse HandleRequest(IRequest request)
{
foreach (var factory in _factoryImplementations)
{
if (factory.CanHandle(request))
{
return factory.HandleRequest(request);
}
}
return null;
}
}
class Program
{
static void Main()
{
var manager = new FactoryManager();
manager.Register(new FooFactory());
var foo = (Foo) manager.HandleRequest(new FooRequest()); // How can I remove this cast?
foo.SpecificMethod();
Console.ReadLine();
}
}
The purpose of this implementation is to make it easy to replace implementations whenever I need. The problem is that I have to explicitly cast the type which I made the request for if I want to do anything specific with the object, like accessing foo.SpecificMethod().
Is there any way to have this (Foo) cast gone?
Edit: It's possible to solve this issue with a dynamic variable, but a statically typed way of solving it would be preferrable.
If you want to be able to call a unique function that isn't on the main interface, you will have to cast it (or request a more specific interface with that method on it).
Using an interface means "This method will have these available public methods". You can inherit from multiple interfaces (public interface IMoreSpeific : IGeneric) but you can't make calls to specific class implementations that have other methods without casting it.
You can make something generic like a DoWork() method on your interface, but the purpose of the interface is to have something reusable and generic.
i have this existing code
public interface IRepository<T>
{
void Create(T obj);
T Retrieve(string key);
}
public class ItemRepository : IRepository<Item>
{
public void Create(Item obj)
{
//codes
}
public Item Retrieve(string key)
{
//codes
}
}
i would like to create a General class repository where i have to inject a type of IRepository to the constructor then use its own implementation of the methods. i already have an existing code but it is currently wrong
public class Repository
{
IRepository<T> action = null;
public Repository(IRepository<T> concreteImplementation)
{
this.action = concreteImplementation;
}
public void Create(T obj)
{
action.Create(obj);
}
}
the classes are from EF. if there is no work around for this what will be the best approach?
If I understand you correctly you want a single repository which can create or retrieve an object of any type by delegating to a type specific repository implementation?
How do you imagine this working? you defined this Repository class, but you have to create a concrete implementation of the actual repository in order to use it, and then still have to create an instance of Repository anyway. Why not just use the generic implementation you have to create anyway?
And what about your Retrieve method? How will this look in your Repository class? Will you just return Object? or will you make your method generic?
Anyway to answer your question, you could do this I suppose:
public class Repository
{
IRepository action = null;
public Repository(IRepository concreteImplementation)
{
this.action = concreteImplementation;
}
public void Create<T>(T obj)
{
action.Create(obj);
}
}
but you have to introduce a non generic interface as well, as you can't require an interface with a generic parameter in the constructor without specifying the generic type on the class.
public interface IRepository
{
void Create(object obj);
object Retrieve(string key);
}
Or possibly you could pass in the type into the Create method instead of having a generic parameter:
public class Repository
{
IRepository action = null;
public Repository(IRepository concreteImplementation, Type respositoryType)
{
this.action = concreteImplementation;
expectedType=repositoryType;
}
public void Create(Type type, Object obj)
{
if(type==expected && obj.GetType()==type)
{
action.Create(obj);
}
}
}
but both of these are terrible ideas. Just use the generics and create a repository per type, it'll be best in the long run
I think you might just be missing the definition of T in the context of the general repository class.
Try adding <T> to the it like this:
public class Repository<T>
{
...
}
Sorry couldn't find a relevant SO question.
I use Reflection to get a property (which is another object) of an object using:
public static T GetPropertyValue<T>(this object obj, string propertyName)
{
PropertyInfo prop = obj.GetType().GetProperty(propertyName);
return (T)prop.GetValue(obj, null);
}
I have a (Xero) Api that looks like:
public class XeroCoreApi : XeroApi
{
public AccountsEndpoint Accounts { get; }
public ContactsEndpoint Contacts { get; }
// ...
}
Where the Endpoints inherit a class that looks like:
public abstract class XeroUpdateEndpoint
{
public TResult Update(TResult item);
// ...
}
i.e. I can call updates on the specific entities:
Contacts.Update(...);
When I do call the GetPropertyValue() method I get the Endpoint object from an instance of the XeroCoreApi but I don't know it's methods (really I do, but the compiler doesn't) until run-time.
To obtain the Endpoint I run the command similar to:
var endpoint = _api.GetPropertyValue<object>("Contacts");
// For the sake of this example the "Contacts" is manually
// entered, violating the whole idea of generics
The problem is I can't do something like endpoint.Update(...) (since the endpoint is a var and some endpoint don't particularly inherit the Update() method).
Is it possible to run the method using Reflection? What might the syntax look like?
Summary:
How to call a method (Update()) of an object of type T (i.e. we don't know the object until run-time) using reflection?
E.g. endpoint.Update(...)
If I understand you correctly, you want generic type constraints (not reflection). This gives the compiler the proof that your type satisfies some conditions.
For example, an interface:
public interface IUpdateStuff {
void Update();
}
public class XeroCoreApi : XeroApi, IUpdateStuff {
// implementation here
}
Then you can constrain your generic type:
public TResult Update(TResult item) where TResult : IUpdateStuff ;
Now the compiler will let you:
public TResult Update(TResult item) where TResult : IUpdateStuff {
item.Update(); // <-- this is okay now.
}
EDIT: This assumes your generic type comes from the enclosing class.. which it appears to in your example.
This is part of my code which I need help with:
// simple service locator
public class ServiceManager<TSvc> : IServiceManager<TSvc> where TSvc: class, IService
{
private Dictionary<object, TSvc> services;
public void RegisterService(TSvc service)
{
// omitted code here
this.services.Add(service.GetType(), service); // dictionary
}
public T GetService<T>() where T : TSvc
{
T result = default(T);
TSvc bufResult = null;
if (this.services.TryGetValue(typeof(T), out bufResult))
result = (T)bufResult;
return result;
}
public TSvc GetService(Type serviceType)
{
TSvc result = null;
this.services.TryGetValue(serviceType, out result);
return result;
}
}
Then my domain interfaces:
public interface IItem
{
string Name { get; set; }
}
public interface IRepository<TModel> where TModel : IItem
{
new IEnumerable<TModel> GetItems();
void InsertItem(TModel item);
void UpdateItem(TModel item);
void DeleteItem(TModel item);
}
public interface IService<TModel> where TModel : IItem
{
IRepository<TModel> Repository { get; }
}
Then some of my domain classes:
public class Book: IItem
{
public string Name { get; set; }
}
public class BookRepo: IRepository<Book>
{
new IEnumerable<Book> GetItems();
void InsertItem(Book item);
void UpdateItem(Book item);
void DeleteItem(Book item);
}
public class BookService: IService<Book>
{
IRepository<Book> IService<Book>.Repository { get { return this.Repository; } }
BookRepo Repository { get; set;}
}
Now, if I am interested to use 'BookService' and do something with it, I could get it from service locator like this:
public void DoSomething()
{
var bookService = serviceManager.GetService<BookService>();
bookService.Repository.Insert(new Book());
}
But the problem is that the type of the service is known only at runtime (eg. selection from combobox). So, how would DoSomething method look like?
public void DoSomething()
{
var typeOfService = combobox.SelectedValue.GetType(); // cbx of services
// ??? make use of serviceManager and typeOfService to get appropriate 'service'
service.Repository.Insert(/*new IITem here*/);
}
Also, I would like to know how would you connect IService to IService<TModel>... it could even get to the solution, but I have no idea how. My IService interface is blank for the moment...
I would really appreciate your time. Please let me know if there is something unclear! Thank you!
Update: Based on your answers, I guess the reflection part could be involved (something like NSGaga pointed out), but still, without connecting IService and IService<TModel> I cannot achieve what I want. Who has any idea how to redesign this?
Something like this should work (typing from my head, so you'd need to check the syntax details - but should give you the direction - or I'll add on later)
MethodInfo methodInfo = typeof(ServiceManager).GetMethod("GetService");
MethodInfo methodInfoGeneric = methodInfo.MakeGenericMethod(new[] { typeOfService });
methodInfoGeneric.Invoke(serviceManager, new object[] { });
To call a generic method where the type is only known at runtime requires using reflection.
For example, in your last code sample, you rightly imply that you can't call GetService<BookService>, but you are still adding new Book() to the service. You would also have to use reflection to instantiate the new object, because, again, you don't know the type at compile time. So you would need to use reflection at least three times: Once to call the method that returns the service, once to create the new object, and once to call the insert method on the service.
You can isolate some of this complexity with dependency injection and inversion of control. For example, create a generic method like this:
void CreateNewObject<T>() where T : new()
{
var service = GetServiceFor<T>();
service.Repository.Insert(new T());
}
Now, you only need to use reflection once, to call that method, instead of three times.