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  • Define Default constructor Structuremap in a Generic Repository

    - by Ricky
    Hello guys, I have a generic IRepository that has 2 constructors, one have none parameters, other has the datacontext as parameter. I want to define to structuremap to aways in this case use the parameterless constructor. I want a way to create a parameterless contructor, other solutions that I have seen, they create a new Datacontext and pass it to the constructor that has parameters.

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  • Why does this work?

    - by Fizz
    Why does this work? I'm not complaining, just want to know. void Test() { int a = 1; int b = 2; What<int>(a, b); // Why does this next line work? What(a, b); } void What<T>(T a, T b) { }

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  • VS2010 Implement Generic Interface expansion doesn't use specified type

    - by TJB
    Using the release version of Visual Studio 2010 I think there's a difference in the "Implement Interface" expansion from VS2008 If I speicify an interface and implement it in a class as so: public interface IRepository<T> where T : IModel { T Get<T>(int id); void Update<T>(); int Add<T>(T item); } public class MockRepository : IRepository<MockUser> { // ... } Then use the "Implement Interface" expansion and get this: public class MockRepository : IRepository<MockUser> { public T Get<T>(int id) { throw new NotImplementedException(); } public void Update<T>() { throw new NotImplementedException(); } public int Add<T>(T item) { throw new NotImplementedException(); } } Instead of what I expected public class MockRepository : IRepository<MockUser> { public MockUser Get<MockUser>(int id) { throw new NotImplementedException(); } public void Update<MockUser>() { throw new NotImplementedException(); } public int Add<MockUser>(MockUser item) { throw new NotImplementedException(); } } The IDE uses the type variable name from the generic interface definition T instead of the specified concrete type MockUser. Is this a bug? Or is something new just for VS2010 / .Net 4.0?

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  • Class hierarchy problem (with generic's variance!)

    - by devoured elysium
    The problem: class StatesChain : IState, IHasStateList { private TasksChain tasks = new TasksChain(); ... public IList<IState> States { get { return _taskChain.Tasks; } } IList<ITask> IHasTasksCollection.Tasks { get { return _taskChain.Tasks; } <-- ERROR! You can't do this in C#! I want to return an IList<ITask> from an IList<IStates>. } } Assuming the IList returned will be read-only, I know that what I'm trying to achieve is safe (or is it not?). Is there any way I can accomplish what I'm trying? I wouldn't want to try to implement myself the TasksChain algorithm (again!), as it would be error prone and would lead to code duplication. Maybe I could just define an abstract Chain and then implement both TasksChain and StatesChain from there? Or maybe implementing a Chain<T> class? How would you approach this situation? The Details: I have defined an ITask interface: public interface ITask { bool Run(); ITask FailureTask { get; } } and a IState interface that inherits from ITask: public interface IState : ITask { IState FailureState { get; } } I have also defined an IHasTasksList interface: interface IHasTasksList { List<Tasks> Tasks { get; } } and an IHasStatesList: interface IHasTasksList { List<Tasks> States { get; } } Now, I have defined a TasksChain, that is a class that has some code logic that will manipulate a chain of tasks (beware that TasksChain is itself a kind of ITask!): class TasksChain : ITask, IHasTasksList { IList<ITask> tasks = new List<ITask>(); ... public List<ITask> Tasks { get { return _tasks; } } ... } I am implementing a State the following way: public class State : IState { private readonly TaskChain _taskChain = new TaskChain(); public State(Precondition precondition, Execution execution) { _taskChain.Tasks.Add(precondition); _taskChain.Tasks.Add(execution); } public bool Run() { return _taskChain.Run(); } public IState FailureState { get { return (IState)_taskChain.Tasks[0].FailureTask; } } ITask ITask.FailureTask { get { return FailureState; } } } which, as you can see, makes use of explicit interface implementations to "hide" FailureTask and instead show FailureState property. The problem comes from the fact that I also want to define a StatesChain, that inherits both from IState and IHasStateList (and that also imples ITask and IHasTaskList, implemented as explicit interfaces) and I want it to also hide IHasTaskList's Tasks and only show IHasStateList's States. (What is contained in "The problem" section should really be after this, but I thought puting it first would be way more reader friendly). (pff..long text) Thanks!

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  • C# BinarySearch breaks when inheriting from something that implements IComparable<T>?

    - by Ender
    In .NET the BinarySearch algorithm (in Lists, Arrays, etc.) appears to fail if the items you are trying to search inherit from an IComparable instead of implementing it directly: List<B> foo = new List<B>(); // B inherits from A, which implements IComparable<A> foo.Add(new B()); foo.BinarySearch(new B()); // InvalidOperationException, "Failed to compare two elements in the array." Where: public abstract class A : IComparable<A> { public int x; public int CompareTo(A other) { return x.CompareTo(other.x); } } public class B : A {} Is there a way around this? Implementing CompareTo(B other) in class B doesn't seem to work.

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  • What is the "Dispatcher" design pattern?

    - by Ben Farmer
    What is the "dispatcher" pattern and how would I implement it in code? I have a property bag of generic objects and would like to have the retrieval delegated to a generic method. Currently, I have properties looking for a specific key in the bag. For example: private Dictionary<String, Object> Foo { get; set; } private const String WidgetKey = "WIDGETKEY"; public Widget? WidgetItem { get { return Foo.ContainsKey(WidgetKey) ? Foo[WidgetKey] as Widget: null; } set { if (Foo.ContainsKey(WidgetKey)) Foo[WidgetKey] = value; else Foo.Add(WidgetKey, value); } } It was suggested that this could be more generic with the "dispatcher" pattern, but I've been unable to find a good description or example. I'm looking for a more generic way to handle the property bag store/retrieve.

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  • How can i convert this to a factory/abstract factory?

    - by Amitd
    I'm using MigraDoc to create a pdf document. I have business entities similar to the those used in MigraDoc. public class Page{ public List<PageContent> Content { get; set; } } public abstract class PageContent { public int Width { get; set; } public int Height { get; set; } public Margin Margin { get; set; } } public class Paragraph : PageContent{ public string Text { get; set; } } public class Table : PageContent{ public int Rows { get; set; } public int Columns { get; set; } //.... more } In my business logic, there are rendering classes for each type public interface IPdfRenderer<T> { T Render(MigraDoc.DocumentObjectModel.Section s); } class ParagraphRenderer : IPdfRenderer<MigraDoc.DocumentObjectModel.Paragraph> { BusinessEntities.PDF.Paragraph paragraph; public ParagraphRenderer(BusinessEntities.PDF.Paragraph p) { paragraph = p; } public MigraDoc.DocumentObjectModel.Paragraph Render(MigraDoc.DocumentObjectModel.Section s) { var paragraph = s.AddParagraph(); // add text from paragraph etc return paragraph; } } public class TableRenderer : IPdfRenderer<MigraDoc.DocumentObjectModel.Tables.Table> { BusinessEntities.PDF.Table table; public TableRenderer(BusinessEntities.PDF.Table t) { table =t; } public MigraDoc.DocumentObjectModel.Tables.Table Render(Section obj) { var table = obj.AddTable(); //fill table based on table } } I want to create a PDF page as : var document = new Document(); var section = document.AddSection();// section is a page in pdf var page = GetPage(1); // get a page from business classes foreach (var content in page.Content) { //var renderer = createRenderer(content); // // get Renderer based on Business type ?? // renderer.Render(section) } For createRenderer() i can use switch case/dictionary and return type. How can i get/create the renderer generically based on type ? How can I use factory or abstract factory here? Or which design pattern better suits this problem?

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  • Do I have to allocate and free records when using TList<T> in Delphi?

    - by afrazier
    The question more or less says it all. Given the following record structure: type TPerson = record Name: string; Age: Integer; end; PPerson = ^TPerson; TPersonList = TList<TPerson>; Is the following code valid? procedure ReadPeople(DataSet: TDataSet; PersonList: TPersonList); begin PersonList.Count := DataSet.RecordCount; if DataSet.RecordCount = 0 then Exit; DataSet.First; while not DataSet.Eof do begin PersonList[DataSet.RecNo].Name := DataSet.FieldByName('Name').AsString; PersonList[DataSet.RecNo].Age := DataSet.FieldByName('Age').AsInteger; DataSet.Next; end; end; Do I have to use GetMem/FreeMem to allocate and free records an instance of TPersonList, or am I free to directly access the TPersonList entries directly? My gut says that the code should be valid, though I'm not sure if there's any wrinkles related to record initialization or finalization.

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  • generic programming in C with void pointer.

    - by Nyan
    Hi everyone, even though it is possible to write generic code in C using void pointer(generic pointer), I find that it is quite difficult to debug the code since void pointer can take any pointer type without warning from compiler. (e.g function foo() take void pointer which is supposed to be pointer to struct, but compiler won't complain if char array is passed.) What kind of approach/strategy do you all use when using void pointer in C?

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  • Why does this return zero results?

    - by Jon
    I have a List<List<string>> and when I try to search with the List<string> it returns no results. Any ideas? Thanks List<List<string>> test = new List<List<string>>(); List<string> ff = new List<string>(); ff.Add("1"); ff.Add("ABC 1"); test.Add(ff); ff = new List<string>(); ff.Add("2"); ff.Add("ABC 2"); test.Add(ff); var result = test.Where(x=>x.Contains("ABC")); //result.Count(); is 0

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  • Implementing IComparer<T> For IComparer<DictionaryEntry>

    - by Phil Sandler
    I am using the ObservableSortedDictionary from Dr. WPF. The constructor looks like this: public ObservableSortedDictionary(IComparer<DictionaryEntry> comparer) I am really struggling to create an implementation that satisfies the constructor and works. My current code (that won't compile) is: public class TimeCreatedComparer<T> : IComparer<T> { public int Compare(T x, T y) { var myclass1 = (IMyClass)((DictionaryEntry)x).Value; var myclass2 = (IMyClass)((DictionaryEntry)y).Value; return myclass1.TimeCreated.CompareTo(myclass2.TimeCreated); } } It says I can't cast from T to DictionaryEntry. If I cast directly to IMyClass, it compiles, but I get a runtime error saying I can't cast from DictionaryEntry to IMyClass. At runtime, x and y are instances of DictionaryEntry, which each have the correct IMyClass as their Value.

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  • How to perform a binary search on IList<T>?

    - by Daniel Brückner
    Simple question - given an IList<T> how do you perform a binary search without writing the method yourself and without copying the data to a type with build-in binary search support. My current status is the following. List<T>.BinarySearch() is not a member of IList<T> There is no equivalent of the ArrayList.Adapter() method for List<T> IList<T> does not inherit from IList, hence using ArrayList.Adapter() is not possible I tend to believe that is not possible with build-in methods, but I cannot believe that such a basic method is missing from the BCL/FCL. If it is not possible, who can give the shortest, fastest, smartest, or most beatiful binary search implementation for IList<T>? UPDATE We all know that a list must be sorted before using binary search, hence you can assume that it is. But I assume (but did not verify) it is the same problem with sort - how do you sort IList<T>? CONCLUSION There seems to be no build-in binary search for IList<T>. One can use First() and OrderBy() LINQ methods to search and sort, but it will likly have a performance hit. Implementing it yourself (as an extension method) seems the best you can do.

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  • Hot to get generic type from object type

    - by Murat
    My Classes are; class BaseClass { } class DerivedClass1 : BaseClass { } class GenericClass<T> { } class DerivedClass2 : BaseClass { GenericClass<DerivedClass1> subItem; } I want to access all fields of DerivedClass2 class. I use System.Reflection and FieldInfo.GetValue() method; Bu I cant get subItem field. FieldInfo.GetValue() method return type is "object". And I cant cast to GenericClass<DerivedClass1> or I cant get DerivedClass1 type. I try this with BaseClass BaseClass instance = FieldInfo.Getvalue(this) as GenericClass<BaseClass>; but instance is null. How to get instance with type or how to get only type?

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  • .net runtime type casting when using reflection

    - by Mike
    I have need to cast a generic list of a concrete type to a generic list of an interface that the concrete types implement. This interface list is a property on an object and I am assigning the value using reflection. I only know the value at runtime. Below is a simple code example of what I am trying to accomplish: public void EmployeeTest() { IList<Employee> initialStaff = new List<Employee> { new Employee("John Smith"), new Employee("Jane Doe") }; Company testCompany = new Company("Acme Inc"); //testCompany.Staff = initialStaff; PropertyInfo staffProperty = testCompany.GetType().GetProperty("Staff"); staffProperty.SetValue(testCompany, (staffProperty.PropertyType)initialStaff, null); } Classes are defined like so: public class Company { private string _name; public string Name { get { return _name; } set { _name = value; } } private IList<IEmployee> _staff; public IList<IEmployee> Staff { get { return _staff; } set { _staff = value; } } public Company(string name) { _name = name; } } public class Employee : IEmployee { private string _name; public string Name { get { return _name; } set { _name = value; } } public Employee(string name) { _name = name; } } public interface IEmployee { string Name { get; set; } } Any thoughts? I am using .NET 4.0. Would the new covariant or contravariant features help? Thanks in advance.

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  • XML Serializing a class with a Dictionary<string, List<string>> object

    - by Matt
    Is it possible to implement IXmlSerializable and in my XML file capture an object of type Dictionary ? I have the following public class coolio : IXmlSerializable { private int a; private bool b; private string c; private Dictionary<string, List<string>> coco; public coolio(int _a, bool _b, string _c, Dictionary<string, List<string>> _coco) { a=_a; b=_b; c=_c; coco=_coco; } public System.Xml.Schema.XmlSchema GetSchema() { return null; } public void WriteXml(XmlWriter writer) { const string myType = "coolio"; writer.WriteStartElement(myType); writer.WriteAttributeString("a", a.ToString()); writer.WriteAttributeString("b", b.ToString()); writer.WriteAttributeString("c", c); // How do I add a subelement for Dictionary<string, List<string>> coco? writer.WriteEndElement(); } public void ReadXml(XmlReader reader) { if (reader.MoveToContent() != XmlNodeType.Element || reader.LocalName != "coolio") return; a= int.Parse(reader["a"]); b = bool.Parse(reader["b"]); c= reader["c"]; // How do I read subelement into Dictionary<string, List<string>> coco? } } But I am stumped as to how I could add the Dictionary (XML seriliazed to my XML file)

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  • Type patterns and generic classes in Haskell

    - by finnsson
    I'm trying to understand type patterns and generic classes in Haskell but can't seem to get it. Could someone explain it in laymen's terms? In [1] I've read that "To apply functions generically to all data types, we view data types in a uniform manner: except for basic predefined types such as Float, IO, and ?, every Haskell data type can be viewed as a labeled sum of possibly labeled products." and then Unit, :*: and :+: are mentioned. Are all data types in Haskell automatically versions of the above mentioned and if so how do I figure out how a specific data type is represented in terms of :*:, etc? The users guide for generic classes (ch. 7.16) at haskell.org doesn't mention the predefined types but shouldn't they be handled in every function if the type patterns should be exhaustive? [1] Comparing Approaches to Generic Programming in Haskell, Ralf Hinze, Johan Jeuring, and Andres Löh

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  • Finding a sequence in a List

    - by user113164
    I have a list of integers that I would like to search for a sequence. For example, if i have a master list: 1, 2, 3, 4, 9, 2, 39, 482, 19283, 19, 23, 1, 29 And I want to find sequence: 1, 2, 3, 4 I would like some easy way to fill a subset list with: 1, 2, 3, 4 + the next five integers in the master list And then remove the integers in the subset list from the master list so at the end of the operation, my lists would look like this: Master list: 19, 23, 1, 29 Subset list: 1, 2, 3, 4, 9, 2, 39, 482, 19283 Hope that makes sense. I'm guessing maybe linq would be good for something like this, but I've never used it before. Can anyone help?

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  • Generic property- specify the type at runtime

    - by Lirik
    I was reading a question on making a generic property, but I'm a little confused at by the last example from the first answer (I've included the relevant code below): You have to know the type at compile time. If you don't know the type at compile time then you must be storing it in an object, in which case you can add the following property to the Foo class: public object ConvertedValue { get { return Convert.ChangeType(Value, Type); } } That's seems strange: it's converting the value to the specified type, but it's returning it as an object when the value was stored as an object. Doesn't the returned object still require un-boxing? If it does, then why bother with the conversion of the type? I'm also trying to make a generic property whose type will be determined at run time: public class Foo { object Value {get;set;} Type ValType{get;set;} Foo(object value, Type type) { Value = value; ValType = type; } // I need a property that is actually // returned as the specified value type... public object ConvertedValue { get { return Convert.ChangeType(Value, ValType); } } } Is it possible to make a generic property? Does the return property still require unboxing after it's accessed?

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  • Is there a way to achieve covariance of generic types in C# 3.0?

    - by nullDev
    This has been introduced in C# 4.0, but is there a way to achieve this in c# 3.0? For e.g., consider the following code: class Base { } class Derived1 : Base { } class Derived2 : Base { } class User<T> where T : Base { } class User1 : User<Derived1> { } Now, I would like to have a list of User<T>, in which I can store User<Derived1> as well as User<Derived2>, but the following code fails to compile in C# 3.0: List<User<Base>> users = new List<User<Base>>(); users.Add(new User1()); Any ideas?

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  • Generic overriding tells me this is the same function. Not agree.

    - by serhio
    base class: Class List(Of T) Function Contains(ByVal value As T) As Boolean derived class: Class Bar : List(Of Exception) ' Exception type as example ' Function Contains(Of U)(ByVal value As U) As Boolean compiler tells me that that two are the same, so I need to declare Overloads/new this second function. But I want use U to differentiate the type (one logic) like NullReferenceException, ArgumentNull Exception, etc. but want to leave the base function(no differentiation by type - other logic) as well.

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  • Generic Dictionary C#

    - by pm_2
    I have a class that inherits from a generic dictionary as follows: Class myClass : System.Collections.Generic.Dictionary<int, Object> I have added a list of values to this in a particular order, but I now wish to change that order. Is there any way (without removing and re-adding) that I could effectively re-index the values; so change the object at index 1 to now be at index 10 for example? For example, this doesn't work: myClass[1].Index = 10;

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