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  • How can I define multiple types with the same name and different type parameters using Reflection Em

    - by wawa
    How can I generate types like these using the System.Reflection.Emit libraries: public class Test<T> {} public class Test<T1, T2> {} When I call ModuleBuilder.DefineType(string) with the second type declaration, I get an exception because there is already another type in the module with the same name (I've already defined the type parameter on the first type). Any ideas?

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  • Suggestions on Working with this Inherited Generic Method

    - by blu
    We have inherited a project that is a wrapper around a section of the core business model. There is one method that takes a generic, finds items matching that type from a member and then returns a list of that type. public List<T> GetFoos<T>() { List<IFoo> matches = Foos.FindAll( f => f.GetType() == typeof(T) ); List<T> resultList = new List<T>(); foreach (var match in matches) { resultList.Add((T)obj); } } Foos can hold the same object cast into various classes in inheritance hierarchy to aggregate totals differently for different UI presentations. There are 20+ different types of descendants that can be returned by GetFoos. The existing code basically has a big switch statement copied and pasted throughout the code. The code in each section calls GetFoos with its corresponding type. We are currently refactoring that into one consolidated area, but as we are doing that we are looking at other ways to work with this method. One thought was to use reflection to pass in the type, and that worked great until we realized the Invoke returned an object, and that it needed to be cast somehow to the List <T>. Another was to just use the switch statement until 4.0 and then use the dynamic language options. We welcome any alternate thoughts on how we can work with this method. I have left the code pretty brief, but if you'd like to know any additional details please just ask.

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  • Why does Generic class signature requires specifying new() if type T needs instantiation ?

    - by this. __curious_geek
    I'm writing a Generic class as following. public class Foo<T> : where T : Bar, new() { public void MethodInFoo() { T _t = new T(); } } As you can see the object(_t) of type T is instantiated at run-time. To support instantiation of generic type T, language forces me to put new() in the class signature. I'd agree to this if Bar is an abstract class but why does it need to be so if Bar standard non-abstract class with public parameter-less constructor. compiler prompts following message if new() is not found. Cannot create an instance of the variable type 'T' because it does not have the new() constraint

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  • A strange error in java generic.

    - by ???
    This is ok: Class<? extends String> stringClass = "a".getClass(); But this gets error: <T> void f(T obj) { Class<? extends T> objClass = obj.getClass(); } I know I can cast it like: <T> void f(T obj) { @SuppressWarnings("unchecked") Class<? extends T> objClass = (Class<? extends T>) obj.getClass(); } But why the previous error? Will the next release of Java 7 will support such usage?

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  • is this possible: c# collection of Type with constrains, or collection of generic type?

    - by Jon
    I'm trying to store types in a collection, so that i can later instantiate objects of the types in the collection. But I'm not sure how to do this the best way. What i have so far: List<Type> list = new List<Type>(); list.Add(typeof(MyClass)); var obj = (MyClass)Activator.CreateInstance(list[0]); I would like to have some constrains on the Type, or better yet, just a generic type in the collection instead of an instantiated Type object. Is this possible?

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  • Decrement all int values in Dictionary

    - by Jon
    I have a Dictionary<string,int> and I simply want to decrement the value in my dictionary by one. I have this but not sure if its best practice. foreach (KeyValuePair<string, int> i in EPCs) { EPCs[i.Key] = i.Value - 1; }

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  • How can I define a constructor in an open generic type?

    - by Cort
    I am trying to create on open generic type that has a constructor to be used by derived types, but I either don't know how to do it or it is not possible -- not sure which. public struct DataType<T> : IDataType { private T myValue; private TypeState myState; private DataType<T>(T initialValue, TypeState state) { myValue = initialValue; myState = state; } } Any help much appreciated! Cort

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  • How to return a value based on the type of the generic T

    - by Blankman
    I have a method like: public T Get<T>(string key) { } Now say I want to return "hello" if the type is a string, and 110011 if it is type int. how can I do that? typeof(T) doesn't seem to work. I ideally want to do a switch statement, and return something based on the Type of the generic (string/int/long/etc). Is this possible?

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  • C# determining generic type

    - by Chris Klepeis
    I have several templated objects that all implement the same interface: I.E. MyObject<datatype1> obj1; MyObject<datatype2> obj2; MyObject<datatype3> obj3; I want to store these objects in a List... I think I would do that like this: private List<MyObject<object>> _myList; I then want to create a function that takes 1 parameter, being a datatype, to see if an object using that datatype exists in my list.... sorta clueless how to go about this. In Pseudo code it would be: public bool Exist(DataType T) { return (does _myList contain a MyObject<T>?); }

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  • Using overloaded operator== in a generic function

    - by Dimitri C.
    Consider the following code: class CustomClass { public CustomClass(string value) { m_value = value; } public static bool operator==(CustomClass a, CustomClass b) { return a.m_value == b.m_value; } public static bool operator!=(CustomClass a, CustomClass b) { return a.m_value != b.m_value; } public override bool Equals(object o) { return m_value == (o as CustomClass).m_value; } public override int GetHashCode() { return 0; /* not needed */ } string m_value; } class G { public static bool enericFunction1<T>(T a1, T a2) where T : class { return a1.Equals(a2); } public static bool enericFunction2<T>(T a1, T a2) where T : class { return a1==a2; } } Now when I call both generic functions, one succeeds and one fails: var a = new CustomClass("same value"); var b = new CustomClass("same value"); Debug.Assert(G.enericFunction1(a, b)); // Succeeds Debug.Assert(G.enericFunction2(a, b)); // Fails Apparently, G.enericFunction2 executes the default operator== implementation instead of my override. Can anybody explain why this happens?

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  • Generic collection class?

    - by Mark
    Is there anyway I can do this? class TSOC<TCollection, TValue> : ICollection<TValue>, INotifyCollectionChanged where TCollection : ICollection { private TCollection<TValue> collection; } It doesn't like my definition of collection. I'd prefer the definition to look like TSOC<TCollection> where the user can pass in List<int> or something, but then I need to pull out the "int" to know what interface to implement.

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  • How to get all possible generic type in StructureMap?

    - by Soul_Master
    I just used StructureMap few days ago. I use StructureMap for collecting all validator class like the following code. public class BaseClassA {} public class ClassB : BaseClassA {} public class ClassC : BaseClassB {} public BaseClassAValidator : IValidator<BaseClassA>() {} In StructureMap, I only register IValidator interface for BaseClassAValidator class. But I want to get the same result when I call IValidator or IValidator that mean StructureMap should return IValidator where T is requested class or parent class of requested class. Is it possible? Or I need to manually call it.

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  • Generic Event Generator and Handler from User Supplied Types?

    - by JaredBroad
    I'm trying to allow the user to supply custom data and manage the data with custom types. The user's algorithm will get time synchronized events pushed into the event handlers they define. I'm not sure if this is possible but here's the "proof of concept" code I'd like to build. It doesn't detect T in the for loop: "The type or namespace name 'T' could not be found" class Program { static void Main(string[] args) { Algorithm algo = new Algorithm(); Dictionary<Type, string[]> userDataSources = new Dictionary<Type, string[]>(); // "User" adding custom type and data source for algorithm to consume userDataSources.Add(typeof(Weather), new string[] { "temperature data1", "temperature data2" }); for (int i = 0; i < 2; i++) { foreach (Type T in userDataSources.Keys) { string line = userDataSources[typeof(T)][i]; //Iterate over CSV data.. var userObj = new T(line); algo.OnData < typeof(T) > (userObj); } } } //User's algorithm pattern. interface IAlgorithm<TData> where TData : class { void OnData<TData>(TData data); } //User's algorithm. class Algorithm : IAlgorithm<Weather> { //Handle Custom User Data public void OnData<Weather>(Weather data) { Console.WriteLine(data.date.ToString()); Console.ReadKey(); } } //Example "user" custom type. public class Weather { public DateTime date = new DateTime(); public double temperature = 0; public Weather(string line) { Console.WriteLine("Initializing weather object with: " + line); date = DateTime.Now; temperature = -1; } } }

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  • Call Generic method using runtime type and cast return object

    - by markpirvine
    I'm using reflection to call a generic method with a type determined at runtime. My code is as follows: Type tType = Type.GetType(pLoadOut.Type); MethodInfo method = typeof(ApiSerialiseHelper).GetMethod("Deserialise", new Type[] { typeof(string) }); MethodInfo generic = method.MakeGenericMethod(tType); generic.Invoke(obj, new object[] { pLoadOut.Data }); This works ok. However the generic.Invoke method returns an object, but what I would like is the type determined at runtime. Is this possible with this approach, or is there a better option? Mark

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  • Generic object comparison diff routine

    - by MicMit
    The question stems from database tables comparison. Let's say we put left row in the instance Left and the right one into instance Right of the same type. And we'got many tables and respective types. How to implement more or less generic routine resulting in a collection of diffs e.g. propertyName , leftValue , rightValue for each such a pair of instances of the same type.

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  • Why does my WCF service return and ARRAY instead of a List <T> ?

    - by user193189
    In the web servce I say public List<Customer> GetCustomers() { PR1Entities dc = new PR1Entities(); var q = (from x in dc.Customers select x).ToList(); return q; } (customer is a entity object) Then I generate the proxy when I add the service.. and in the reference.cd it say public wcf1.ServiceReference1.Customer[] GetCustomers() { return base.Channel.GetCustomers(); } WHY IS IT AN ARRAY? I asked for a List. help.

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  • List of Lists of different types

    - by themarshal
    One of the data structures in my current project requires that I store lists of various types (String, int, float, etc.). I need to be able to dynamically store any number of lists without knowing what types they'll be. I tried storing each list as an object, but I ran into problems trying to cast back into the appropriate type (it kept recognizing everything as a List<String>). For example: List<object> myLists = new List<object>(); public static void Main(string args[]) { // Create some lists... // Populate the lists... // Add the lists to myLists... for (int i = 0; i < myLists.Count; i++) { Console.WriteLine("{0} elements in list {1}", GetNumElements(i), i); } } public int GetNumElements(int index) { object o = myLists[index]; if (o is List<int>) return (o as List<int>).Count; if (o is List<String>) // <-- Always true!? return (o as List<String>).Count; // <-- Returning 0 for non-String Lists return -1; } Am I doing something incorrectly? Is there a better way to store a list of lists of various types, or is there a better way to determine if something is a list of a certain type?

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  • Operation Problems in Java Generic

    - by alantheweasel
    I got some problem when i was learning Java Generic : interface calculator<T, R> { public void execute(T t, R r); } class executeAdd<T, R> implements calculator<T, R> { private T first; private R second; public executeAdd(T first, R second) { super(); this.first = first; this.second = second; } @Override public void execute(T t, R r) { // TODO Auto-generated method stub Object o = t + r // ERROR ! What i could do it ? } }

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  • Generic type parameter naming convention for Java (with multiple chars)?

    - by chaper29
    In some interfaces i wrote I'd like to name generic type parameter with more than one character to make the code more readable. Something like.... Map<Key,Value> Instead of this... Map<K,V> But when it comes to methods, the type-parameters look like java-classes which is also confusing. public void put(Key key, Value value) This seems like Key and Value are classes. I found or thought of some notations, but nothing like a convention from sun or a general best-practice. Alternatives i guesed of or found... Map<KEY,VALUE> Map<TKey,TValue>

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