reference

问题 We all know that things like this are valid in c++: const T &x = T(); while: T &x = T(); is not. In a recent question the conversation lead to this rule. The OP had posted some code which clearly evokes UB. But I would have expect a modified version of it to work (This is the modified version): #include <iostream> using namespace std; class A { public: A(int k) { _k = k; }; int get() const { return _k; }; int _k; }; class B { public: B(const A& a) : _a(a) {} void b() { cout << _a.get(); }

问题 I'm having a hard time finding the answer to this question I assume is not that hard. How can I reference methods and properties defined on a viewcontroller from a SKScene ? And building on that: How can you reference the ViewController from a SKScene that was loaded from within another SKScene? 回答1: A better option than my "back reference" answer is to use a protocol to explicitly define the methods that a SKScene subclass expects the UIViewController subclass to implement. Here are the

问题 I'm pretty new to this, so I'm sorry if I screw up any of the lingo. Thanks a bunch for anybody's help or thoughts. I have the following wrong code: Sub ExampleSub(text As String) ClassObject." & text & "_attribute = 1 End Sub So if I call ExampleSub("cheese"), I would like it to set ClassObject.cheese_attribute equal to 1. Any thoughts? I'm not even sure it's possible. Thanks so much! 回答1: Here is another method that might work. Use a scripting dictionary object as one of the classobject's

问题 What is value semantics and reference semantics and what is the difference between them? Can you please show me with an example in c. I guess in reference semantics that you just send an pointer to another function then it is reference semantics? I find it hard to grasp what value semantics is? If I only use an int as an argument and then let say return an int from that function then the function uses value semantics? And how does side effects affect this? There must be other examples of

问题 I'm looking for a way to essentially give an item in a ResourceDictionary multiple keys. Is there a way to do this? <DataTemplate x:Key="myTemplate" ... /> <AliasedResource x:Key="myTemplateViaAlias" Target="myTemplate" OR_Target={StaticResource myTemplate} /> When I call TryFindResource("myTemplateViaAlias") I want to get myTemplate out. I suppose I could create an AliasedResource class myself and dereference it in code when I get it out of the dictionary, but I'd rather not do that if there

问题 I have a Java class with native functions implemented in C++ which is called nz.ac.unitec.BigInteger . The native implementation of nz.ac.unitec.BigInteger is simple, just wraps the java.math.BigInteger and call its constructor and add , subtract , multiply ... functions. A field mNativeContext in nz.ac.unitec.BigInteger is used to store a global reference to a java.math.BigInteger object. The object has a finalizer that should destroy the global reference when the object is garbage collected

问题 So this works.. public MyClass(ref Apple apple) { apple = new Apple("Macintosh"); // Works fine } But is it possible to do something like this? private Apple myApple; public MyClass(ref Apple apple) { myApple = apple; } public void ModifyApple() { myApple = new Apple("Macintosh"); // does not change the input variable like the first example did } When the ref variable is copied to the member variable myApple it appears to lose it's 'ref-ness' and re-assigning it no longer changes the input

问题 When you unload a project in Visual Studio, any referencing projects get warning triangles on their reference to the unloaded project. I've written myself a macro to do clever stuff (detect add/remove of project and transform any references from-to file/project dependency), but I can't believe that I'm not missing something much simpler. How can the unload function be any use if I have to go around manually changing references (and it breaks the 'personal solutions/shared projects' team

问题 When you unload a project in Visual Studio, any referencing projects get warning triangles on their reference to the unloaded project. I've written myself a macro to do clever stuff (detect add/remove of project and transform any references from-to file/project dependency), but I can't believe that I'm not missing something much simpler. How can the unload function be any use if I have to go around manually changing references (and it breaks the 'personal solutions/shared projects' team

问题 I would like to patch some text data extracted from web pages. sample: t="First sentence. Second sentence.Third sentence." There is no space after the point at the end of the second sentence. This sign me that the 3rd sentence was in a separate line (after a br tag) in the original document. I want to use this regexp to insert "\n" character into the proper places and patch my text. My regex: t2=t.gsub(/([.\!?])([A-Z1-9])/,$1+"\n"+$2) But unfortunately it doesn't work: "NoMethodError: