extension-methods

问题 I can't quite come up with the solution to creating a generic method to handle the InvokeRequired for void methods (I'll deal with return values later). I was thinking something like: // Probably not the best name, any ideas? :) public static void CheckInvoke(this Control instance, ,Action<object, object> action) { if (instance.InvokeRequired) { instance.Invoke(new MethodInvoker(() => action)); } else { action() } } Then I could write something like: public partial class MyForm : Form {

问题 I have to implement generic extention deepclone method which can be used with any reference type instance to get its deep copy. I implement it as the following static class ClassCopy { static public T DeepClone<T> (this T instance) { if (instance == null) return null; var type = instance.GetType(); T copy; var flags = BindingFlags.FlattenHierarchy | BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance; var fields = type.GetFields(flags); // If type is serializable - create

问题 Sorry for this long question, it is flagged wiki since I'm asking for something that might not have a very concrete answer. If it is closed, so be it. My main question is this: How would you write a fluent interface that isn't fully defined in the base classes, so that programs that uses the fluent interfaces can tack on new words inside the existing structure, and still maintain a guiding interface so that after a dot, the intellisense only lists the keywords that actually apply at this

问题 I'm trying to write an extension method in .NET that will operate on a generic collection, and remove all items from the collection that match a given criteria. This was my first attempt: public static void RemoveWhere<T>(this ICollection<T> Coll, Func<T, bool> Criteria){ foreach (T obj in Coll.Where(Criteria)) Coll.Remove(obj); } However this throws an InvalidOperationException, "Collection was modified; enumeration operation may not execute". Which does make sense, so I made a second

问题 I found in MSDN's Linq samples a neat method called Fold() that I want to use. Their example: double[] doubles = { 1.7, 2.3, 1.9, 4.1, 2.9 }; double product = doubles.Fold((runningProduct, nextFactor) => runningProduct * nextFactor); Unfortunately, I can't get this to compile, either in their example or in my own code, and I can't find anywhere else in MSDN (like Enumerable or Array extension methods) that mention this method. The error I get is a plain old "don't know anything about that"

问题 Background: In the spirit of "program to an interface, not an implementation" and Haskell type classes, and as a coding experiment, I am thinking about what it would mean to create an API that is principally founded on the combination of interfaces and extension methods. I have two guidelines in mind: Avoid class inheritance whenever possible. Interfaces should be implemented as sealed class es. (This is for two reasons: First, because subclassing raises some nasty questions about how to

问题 I have a huge memory leak problem involving a C-extension I'm developing. In C, I have an array of doubles called A and an int variable called AnotherIntVariable that I want to pass to Python. Well, in my C-extension module I do the following: int i; PyObject *lst = PyList_New(len_A); PyObject *num; if(!lst) return NULL; for(i=0;i<len_A;i++){ num=PyFloat_FromDouble(A[i]); if(!num){ Py_DECREF(lst); return NuLL; } PyList_SET_ITEM(lst,i,num); } free(A); return Py_BuildValue("Oi",lst

问题 In our .aspx pages, we've got lots of this code: <%= CType(GetLocalResourceObject("key"), String)) %> I'd like to add an extension method that I can use in our .aspx views that allows me to do this: <%= GetLocalResourceString("key") %> The code isn't working, though: Imports System.Runtime.CompilerServices Imports System.Web.UI Module Extensions <Extension()> Public Function GetLocalResourceString(ByVal control as TemplateControl, ByVal resourceKey as String) as String Return CType(control

问题 The following code snippet is copied from the official document where it is used to demonstrate how to use the Extensions to add method to existing types. extension Int { func repetitions(task: () -> Void) { for _ in 0..<self { task()//what's going on here? } } } 3.repetitions { //why I don't have to call as `repetitions()` print("Hello!") } Question: The question is not asking how the extinsion extens. I just feel a bit confused about this code, why it looks like so? why use task() inside

问题 I have defined following code in C++ CLI. However when I want to call SetColor the first parameter which is supposed to appear as System.Drawing.Color; appears as ValueType. This also let me to pass any variable into it. No matter if it's Color or not. [System::Runtime::CompilerServices::ExtensionAttribute] public ref class MyExtensions abstract sealed { public: [System::Runtime::CompilerServices::ExtensionAttribute] static System::String^ SetColor(System::String^ in, System::Drawing::Color^