No, this has not to do with C++’s grammar, but with lazy instantiation of C++ templates and two phase lookup. In C++, a dependent name is a name or symbol whose meaning depends on one or more template parameters: template <typename T> struct Foo { Foo () { const int x = 42; T::Frob (x); … Read more
Unfortunately, what you want to do is not possible in XAML (from MSDN): Your custom class must not be a nested class. Nested classes and the “dot” in their general CLR usage syntax interfere with other WPF and/or XAML features such as attached properties.
Drink.COFFEE.getGroupName(); Drink.COFFEE.COLUMBIAN.getLabel(); First off, that sample code you gave violates the “law of demeter” somewhat – as the COLUMBIAN instance field is only used to retrieve the label. Also, with that structure, COLUMBIAN has to be an instance of the COFFEE enum, but I don’t think that’s what you’re really going for here. someMethod(Drink type) … Read more
You’ve answered your own question. Use nested classes when you need a helper class that is meaningless outside the class; particularly when the nested class can make use of private implementation details of the outer class. Your argument that nested classes are useless is also an argument that private methods are useless: a private method … Read more
This question is pretty old, and I don’t know if it would have worked with the version of WPF back in 2010, but now you can make it work by using the “real” (internal) name of the nested type: <local:A+B /> If you’ve ever looked a disassembled code, that’s how nested types look like: ParentTypeName+Nested
Actually there is a complete and simple solution to this problem that doesn’t involve modifying the client code or creating an interface. This solution is actually faster than the interface-based solution for most cases, and easier to code. public class Journal { private static Func<object, JournalEntry> _newJournalEntry; public class JournalEntry { static JournalEntry() { _newJournalEntry … Read more
After having asked more or less the same question here myself, I wanted to share the (apparently) updated answer for C++11: Quoted from https://stackoverflow.com/a/14759027/1984137: standard $11.7.1 “A nested class is a member and as such has the same access rights as any other member. The members of an enclosing class have no special access to … Read more
A pattern that I particularly like is to combine nested classes with the factory pattern: public abstract class BankAccount { private BankAccount() {} // prevent third-party subclassing. private sealed class SavingsAccount : BankAccount { … } private sealed class ChequingAccount : BankAccount { … } public static BankAccount MakeSavingAccount() { … } public static BankAccount … Read more