circular-dependency | 易学教程

C++ circular include

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问题 I can't solve this circular dependency problem; always getting this error: "invalid use of incomplete type struct GemsGame" I don't know why the compiler doesn't know the declaration of GemsGame even if I included gemsgame.h Both classes depend on each other (GemsGame store a vector of GemElements, and GemElements need to access this same vector) Here is partial code of GEMELEMENT.H: #ifndef GEMELEMENT_H_INCLUDED #define GEMELEMENT_H_INCLUDED #include "GemsGame.h" class GemsGame; class

Can dependency injection prevent a circular dependency?

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问题 Project#1 has some interfaces and classes that project#2 references. Now I want to use the implementation of Project#2 in Project#1 but vs.net complains about a circular dependency. If I was to use dependancy injection in Project#1 and bind to the implementation in Project#2 (since it adheres to the interface contract), will this work or I will still get the circular dependency error message at runtime? 回答1: You probably could solve this with DI, but you shouldn't . If I understand correctly,

Circular C++ Header Includes

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In a project I have 2 classes: // mainw.h #include "IFr.h" ... class mainw { public: static IFr ifr; static CSize=100; ... }; // IFr.h #include "mainw.h" ... class IFr { public float[mainw::CSize]; }; But I cannot compile this code, getting an error at the static IFr ifr; line. Is this kind of cross-inclusion prohibited? Is this kind of cross-inclusions are prohibited? Yes. A work-around would be to say that the ifr member of mainw is a reference or a pointer, so that a forward-declaration will do instead of including the full declaration, like: //#include "IFr.h" //not this class IFr; //this

Circular dependency in java classes

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I have the following classes. public class B { public A a; public B() { a= new A(); System.out.println("Creating B"); } } and public class A { public B b; public A() { b = new B(); System.out.println("Creating A"); } public static void main(String[] args) { A a = new A(); } } As can be clearly seen, there is a circular dependency between the classes. if I try to run class A, I eventually get a StackOverflowError . If a dependency graph is created, where nodes are classes, then this dependency can be easily identified (at least for graphs with few nodes). Then why does the JVM not identify this

How to solve circular reference?

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How do you solve circular reference problems like Class A has class B as one of its properties, while Class B has Class A as one of its properties? How to do architect for those kind of problems? If you take an example of NHibernate, there will be a parent-child relationship between objects. How is it able to handle those parent child scenarios? In most cases when I've had to have two things reference each other, I've created an interface to remove the circular reference. For example: BEFORE public class Foo { Bar myBar; } public class Bar { Foo myFoo; } Dependency graph: Foo Bar ^ ^ | | Bar

Pros & Cons of putting all code in Header files in C++?

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问题 You can structure a C++ program so that (almost) all the code resides in Header files. It essentially looks like a C# or Java program. However, you do need at least one .cpp file to pull in all the header files when compiling. Now I know some people would absolutely detest this idea. But I haven't found any convincing downsides of doing this. I can list some advantages: [1] Faster compile times. All header files only get parsed once, because there is only one .cpp file. Also, one header file

Python mutually dependent classes (circular dependencies)

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问题 I've searched a lot, but what I find is mainly examples of recursive programming in python. So here goes the question: How can I achieve this? class A: b = B() class B: a = A() 回答1: Everything is dynamic in Python - even the class declarations. There's nothing to stop you modifying the contents of a class after the initial declaration: class A: pass class B: a = A() A.b = B() NB: If you're not that familiar with Python, the pass keyword simply allows you to say 'nothing here' - it's not

Circular Dependency in C++

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问题 The facts: I have two predominant classes: Manager and Specialist. There are several different types of Specialists. Specialists often require the help of other Specialists in order to get their job done. The Manager knows all of the Specialists, and initially each Specialist knows only their Manager. (This is the problem.) At runtime, the Manager creates and stores a list of Specialists. Then the Manager iterates through the list and asks each Specialist to initialize. During their

Does Objective-C allow circular dependencies?

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问题 I'm rewriting a Java library in Objective-C and I've come across a strange situation. I've got two classes that import each other. It's a circular dependency. Does Objective-C support such a situation? If not, how do you recommend I rewrite it? 回答1: Importing a class is not inheritance. Objective-C doesn't allow circular inheritance, but it does allow circular dependencies. What you would do is declare the classes in each other's headers with the @class directive, and have each class's

forward declaration with vector of class type - pointer to incomplete class type not allowed

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问题 I have two classes, foo and bar . foo.h #include s bar.h and contains a std::vector of pointers to bar objects. At some point during runtime, bar has to access this vector of pointers to other bar objects. Therefore, foo contains a method named getBarObjects() that returns the array of pointers. Therefore, I forward declare foo in bar.h. I obviously also have to forward declare the method I'm using - foo::getBarObjects() . As this returns the array of pointers to bar , I get into a vicious