late-binding

问题 I am trying to create an application that creates objects from data that is read from an XML file. Using reflection I have managed to create the objects I need and assign some of the properties like primitive types and ENUM types. For primitive types where property is a Dictionary entry with the Property name to change and the value to set type.GetProperty((string)property.Key).SetValue(control, Convert.ChangeType((string)property.Value, propertyType, null), null); and for ENUM types object

问题 I've seen both used interchangebly but do they really mean the same? From my understanding, Polymorphism stretches the fact that you could exchange an instance of a class by an instance of a subclass, and Late Binding means that when you call a method of an instance, the type decides which method (subclass/superclass) gets called. 回答1: Wikipedia has a very nice article about this: http://en.wikipedia.org/wiki/Polymorphism_in_object-oriented_programming Summary: Late binding is a way to

问题 Starting with version 5.3, PHP supports late binding for static methods. While it's an undoubtedly useful feature, there are only several cases where its use is really necessary (e.g. the Active Record pattern). Consider these examples: 1. Convenience constructors ( ::create() ) class SimpleObject { public function __construct() { /* ... */ } public static function create() { return new static; // or: return new self; } } If this class may be extended (however, it's not extended by any class

问题 I have a question on C++ double dispatch. In the code below, I want the results from the second set to match the results from the first set. I don't know the actual type (unless I try dynamic_cast) but I do know that the object inherited from the BaseClass type. What is the most efficient (performance-wise) way to accomplish this? After googling around for a while I found out about double dispatch and the loki multimethods. The problem I have with the Shape examples is that in my application,

问题 Can I make an Extension method for all the subclasses of System.Object (everything)? Example: <Extension> Public Function MyExtension(value As Object) As Object Return value End Function The above functions won't work for object instance: Dim myObj1 As New Object() Dim myObj2 = myObj1.MyExtension() The compiler does not accept it, is the problem in my computer? :) UPDATE The problem seems to occur only in VB, where members of object are looked-up by reflection (late-bound). UPDATE AFTER

问题 The following test fails: #!/usr/bin/env python def f(*args): """ >>> t = 1, -1 >>> f(*map(lambda i: lambda: i, t)) [1, -1] >>> f(*(lambda: i for i in t)) # -> [-1, -1] [1, -1] >>> f(*[lambda: i for i in t]) # -> [-1, -1] [1, -1] """ alist = [a() for a in args] print(alist) if __name__ == '__main__': import doctest; doctest.testmod() In other words: >>> t = 1, -1 >>> args = [] >>> for i in t: ... args.append(lambda: i) ... >>> map(lambda a: a(), args) [-1, -1] >>> args = [] >>> for i in t: ..

问题 From wikipedia: Dynamic loading is a mechanism by which a computer program can, at run time, load a library (or other binary) into memory, retrieve the addresses of functions and variables contained in the library, execute those functions or access those variables, and unload the library from memory. Late binding is a computer programming mechanism in which the method being called upon an object is looked up by name at run-time. In my opinion, A similarity is they are both mechanisms in which

问题 I've done this before in C# for a plugin system which works fine, which is why I'm puzzled as to why this new, separate plugin system is not working the way I would expect. I have my plugin assembly - let's call it "plugin.dll" and I have my main assembly - let's call it App.exe. I have an interface called IMyObject and its implementation, MyObject and both are defined in plugin.dll. I've copied the exact code file for IMyObject (which the plugin developer has provided to me) into my main App

问题 The question is intended for lazy VB programmers. Please. In vb I can do and I won't get any errors. Example 1 Dim x As String = 5 Dim y As Integer = "5" Dim b As Boolean = "True" Example 2 Dim a As EnumType = 4 Dim v As Integer = EnumType.EnumValue Example 3 Private Sub ButtonClick(sender As Object, e As EventArgs) Dim btn As Button = sender End Sub Example 4 Private Sub ButtonClick(sender As Button, e As EventArgs) Dim data As Contact = sender.Tag End Sub If I surely know the expected

问题 About the limitation As per Microsoft's official docs, late binding only works on public methods. Late binding can only be used to access type members that are declared as Public. Accessing members declared as Friend or Protected Friend results in a run-time error. I've been curious as to why this restriction was put in. It seems a bit strange from a language design perspective that early binding respects access rights for methods, but late binding only supports public methods. Example