multiple-inheritance

Is __init__ a class method?

由 若如初见. 提交于 2019-12-05 02:56:44
I was looking into Python's super method and multiple inheritance. I read along something like when we use super to call a base method which has implementation in all base classes, only one class' method will be called even with variety of arguments. For example, class Base1(object): def __init__(self, a): print "In Base 1" class Base2(object): def __init__(self): print "In Base 2" class Child(Base1, Base2): def __init__(self): super(Child, self).__init__('Intended for base 1') super(Child, self).__init__()# Intended for base 2 This produces TyepError for the first super method. super would

vb.net: multiple inheritance in an interface

由 房东的猫 提交于 2019-12-05 01:35:06
I'm facing a problem regarding multiple inheritance in VB.net: As far as I know VB.net does not support multiple inheritance in general but you can reach a kind of multiple inheritance by working with interfaces (using “Implements” instead of “Inherits”): Public Class ClassName Implements BaseInterface1, BaseInterface2 End Class That works fine for classes but I’d like to have an interface inheriting some base interfaces. Something like that: Public Interface InterfaceName Implements BaseInterface1, BaseInterface2 End Interface But the “Implements” keyword is not allowed for interfaces (what

Why doesn't OrderedDict use super?

由 半城伤御伤魂 提交于 2019-12-05 00:51:37
问题 We can create an OrderedCounter trivially by using multiple inheritance: >>> from collections import Counter, OrderedDict >>> class OrderedCounter(Counter, OrderedDict): ... pass ... >>> OrderedCounter('Mississippi').items() [('M', 1), ('i', 4), ('s', 4), ('p', 2)] Correct me if I'm wrong, but this crucially relies on the fact that Counter uses super: class Counter(dict): def __init__(*args, **kwds): ... super(Counter, self).__init__() ... That is, the magic trick works because >>>

Multiple inheritance pointer comparison

由 只愿长相守 提交于 2019-12-04 23:13:06
I have a class Derived that inherits directly from two base classes, Base1 and Base2 . I'd like to know if it's safe, in general, to compare pointers to the base classes to determine if they are the same Derived object: Base1* p1; Base2* p2; /* * Stuff happens here. p1 and p2 now point to valid objects of either their * base type or Derived */ //assert(p1 == p2); //This is illegal assert(p1 == static_cast<Base1*>(p2)); //Is this ok? assert(static_cast<Derived*>(p1) == static_cast<Derived*>(p2)); //How about this? The pointers are guaranteed to be valid, but not necessarily to point to a

Multiple inheritance of interfaces in C++

由 元气小坏坏 提交于 2019-12-04 22:01:57
问题 I have an object interface and a open ended collection of interfaces that a derived object might want to support. // An object class IObject { getAttribute() = 0 } // A mutable object class IMutable { setAttribute() = 0 } // A lockable object class ILockable { lock() = 0 } // A certifiable object class ICertifiable { setCertification() = 0 getCertification() = 0 } Some derived objects might look like this: class Object1 : public IObject, public IMutable, public ILockable {} class Object2 :

Concerning Struct Constructor and Destructor behavior - C++

由 天涯浪子 提交于 2019-12-04 20:34:41
问题 I don't understand why the output of this program is as follows. Why isn't there a compilation error? I thought when trying to construct B, the compiler would find no function called foo() and report an error. #include <iostream> using namespace std; struct A{ int a; A(int i=0) : a(i) { cout << "A" << endl; } ~A() { cout << "Bye A" << endl; } int foo() { return a; } }; struct B{ int b; B(int i=0) : b(i) { cout << "B" << endl; } ~B() { cout << "Bye B" << endl; } int bar() { return b; } };

Java: how do you call this multiple inheritance ambiguity?

由 安稳与你 提交于 2019-12-04 19:17:30
问题 Here's an example using multiple interface inheritance in Java and there's an issue. Note that I fully know why there's an issue and this is not the point of my question. The question is about how you name this particular multiple interface inheritance ambiguity, if there's a name for it. For example, in C++, the ambiguity that arises when you use multiple implementation inheritance and cannot determine which overridden method to use is called the "diamond problem": http://en.wikipedia.org

Java: Why multiple interfaces instead of multiple inheritance? [duplicate]

由 為{幸葍}努か 提交于 2019-12-04 19:12:04
Possible Duplicates: Why does Java allow multiple inheritance from interfaces but not from abstract/concrete classes Why there is no multiple inheritance in Java, but implementing multiple interfaces is allowed Instead of inheriting from multiple classes (which Java doesn't allow), why are we told to implement multiple interfaces instead? Surely the point of inheriting from multiple classes is the inherit their functionality - if you have to manually re-insert functionality (for each class extending a set of interfaces) what's the point of using the interfaces? There's no guarantee that two

Virtual Inheritance and dreaded diamond

由 家住魔仙堡 提交于 2019-12-04 18:35:18
问题 I am having a hard time with a dreaded diamond problem. For a reminder, here is the classical class hierarchy of this problem: B / \ C1 C2 \ / D To solve it, the standard solution is to make C1 and C2 use virtual inheritance to inherit from B. My problem is that B and C1 are from an SDK that I cannot modify. Example below where I cannot make SubClassB inherit virtually from Base . Classes: PureVirtualBase, Base and SubClassB are from the SDK I use. I cannot modify them. SubClassA and Leaf are

subclassing from OrderedDict and defaultdict

由 ℡╲_俬逩灬. 提交于 2019-12-04 18:10:34
问题 Raymond Hettinger showed a really cool way to combine collection classes: from collections import Counter, OrderedDict class OrderedCounter(Counter, OrderedDict): pass # if pickle support is desired, see original post I want to do something similar for OrderedDict and defaultdict. But of course, defaultdict has a different __init__ signature, so it requires extra work. What's the cleanest way to solve this problem? I use Python 3.3. I found a good solution here: https://stackoverflow.com/a
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