Today I faced a problem where I had circular dependency in my template arguments. I was trying to make a class hierarchy similar to:
template<class BType>
class A_base {
public:
BType* getB();
};
[Code] .....
Basically I had objects that were of type A<B<A<B<...
Basically I have a tree like structure of heterogeneous types that must facilitate two-way interactions where A's can call B's and B's can call A's. This structure is useful in many contexts the difference is the methods A and B provide are different in each of these contexts. Instead of adding the getA and getB and all the other connectivity methods in every version of A and every version of B, I wanted to create a base class that managed this automatically.
Another piece of advice was break up your code so there is a forward-only and backwards-only dependent types. This is not a complete solution because the two cannot know about the other and this does not really facilitate arbitrary two-way communication (where A calls B then B calls A back). It also makes the code more complicated in that I have two sets of objects and interfaces.
So the solution was to make the template arguments specific to the things I wanted to be flexible. The connectivity interface of A_base and B_base should be constant. Hence that cannot be in the template parameter. It was merely the traits that I wanted to make flexible so... I came up with this solution:
#include <iostream>
template<class aTraitType,class bTraitType>
class A;
template<class aTraitType,class bTraitType>
class B;
[Code] ....
Now this compiles and works great. The problem is that aObj and bObj cannot call their opposite within a trait method because print() does not know anything about the connectivity. So the solution there was to make traits an abstract base class. Then magically everything works!
#include <iostream>
template<class aTraitType,class bTraitType>
class A_base;
template<class aTraitType,class bTraitType>
class B_base;
[Code] .....
So this outputs the following. Clearly there is two-way communication!
Class A is not connected to B
Class B is not connected to A
Class A at 0x7fff25d1aa10 reporting for duty
Class B at 0x7fff25d1aa00 reporting for duty
Class B at 0x7fff25d1aa00 reporting for duty
Class A at 0x7fff25d1aa10 reporting for duty
Class A at 0x7fff25d1aa10 reporting for duty
Class B at 0x7fff25d1aa00 reporting for duty
where 'g()' returns an object of the element type. However, the compiler is claiming, no matter how I write a call to the overload, the original template is selected and/or the overload is invalid, depending on the various ways I attempt to write said overload.
I'm trying to create a callback wrapper for pointers to member functions of any class by using templates, std::function and std::bind. This will be used to send incoming sf::Event's to classes who register callbacks with an event manager. I based my code off of the example on this page: URL.....Here's what I have:
class EventCallback { std::function<bool(const sf::Event&)> func;
that successfully allows me to enable the function foo() only if FIRST is convertible to Base*, but I also only want foo() enabled if each type in REST... meets the same condition. What is the syntax for that? If no such syntax exists, how to achieve that effect?
I have an exercise from my text that defines a StrBlob class, then a StrBlobPtr class to hold weak pointers to the StrBlobs. This is from C++ Primer (5th Edition) and coincidentally, the entire chapter is available on-line at here.
My problem is that the begin and end functions of StrBlob can't be defined until the entire StrBlobPtr class is defined. Forward declarations don't cut it, since begin and end need more than pointers.
The solution (if you also look at the errata for the book) seems to be to define StrBlob, leave begin and end undefined, then full define StrBlobPtr, and following that, finally define StrBlob::begin() and StrBlob::end().
Anyhow, the above works, as I show in the included code below - but it seems like a hack and messy. What would be the proper way to do this? My text may be obfuscating the issue in the pursuit of pedagogy.
Additionally, how would one separate StrBlob and StrBlobPtr into there own headers? I'd think it impossible, since the StrBlob would have to nestle an "#include "StrBlobPtr.hpp" in the center of it's own definition...?
I have function that returns historical data. I can access it, using file name. If I use file name, it reads that file and saves it to dictionary, so that in the future, if historical data is required for the same file, it does not read it again (it's lazy loading). If no file is supplied to the function, it tries to read file which is given in app settings.
However, for unit testing, I do not want to read any file. Instead, I want it to use small sample of hardcoded historical data. In order to do that, I think, I need to introduce interface to it. Then I can use some IoC to choose between different implementation for unit testing purpose and ordinary launch of application.
Function to get history is given as follows:
public static class Auxiliary { private static Dictionary<string, MyData> _myData; public static MyData GetData(string fileName = null) { // ... } }
I have created default Unit Test project with Visual Studio so, as far as I know, by default it uses MSTest as test runner and MSUnit as unit testing framework but it does not have any IoC container so I should manage NuGet packages for solution and install Unity.
As far as I know, MSUnit (aka Moles) can unit test static methods (it's unconstrained isolation framework, like Typemock Isolator, unlike NUnit) but still many people suggest not to use any static methods for unit testing.
Should I use shim or stub [URL] Stubs should be used for faking external dependencies and here it is not external library, but my own code.
I'm trying to implement a simple template array class, but when i came into the operator< i actually have to use a template :
my code is something like :
template<typename _Type, std::size_t _Size> class array { public :
[Code] ......
but i am having an error of shadows template param 'class _Type' is it w/ the name conflict between the array template parameter and the function template parameter ?
Error1error C2955: 'DoubleLinkedListInterface' : use of class template requires template argument listdoublelinkedlist.h10 Error2error C2244: 'DoubleLinkedList<T>::DoubleLinkedList' : unable to match function definition to an existing declaration doublelinkedlist.cpp7
Error3 .cpperror C2244: 'DoubleLinkedList<T>::~DoubleLinkedList' : unable to match function definition to an existing declaration 12
.h
#pragma once #include "DoubleLinkedListInterface.h" #include "Node.h" #include <iostream>
Let's say I have unsigned char test[10] = "HELLO!!!"; How would I go about circularly shifting this to the right? Inline assembly instructions would be ok too
Any algorithm or function to rotate a displayed circle. To turn it 360 degrees like a car-tire. (It's needed to turn a turn-table in a model-railrod control program) .....
It's compiling but it's not working, it enters in stack overflow. It's a Doubly Linked List I'm compiling in Visual Studio. I think there's nothing wrong with this declaration, but there's just might be it:
class ListItem; class List { public: ListItem *firstItemRef;
I need to create such a function that the content of the first is put into the second, the content of the second into the third and the content of the third into the first.
For example, output should be like this 3 2 1 But the code below prints out: 1 2 2 Where am I making a mistake?
I have a generic template class with another template in one of its types. Now I want to specialize one of its methods for a particular (template) class, which leads to a compile error, however.
GCC ends with: :35:27: error: type/value mismatch at argument 2 in template parameter list for ‘template<class Type, template<class> class O> class Foo’ :35:27: error: expected a class template, got ‘Obj2<Type>’
What is wrong with the specialization? Can it even be achieved and how (if so)?
how I want the code to look. Only problem is it doesn't work (Line 11). I have some experience with templates but I'm not a pro.
Basically I want the "Channels<3>" to be a type that I can use to specify a Cable with similar to vector<float/int> it would be Cable<Channels<2 or 3>>.
What have I messed up with the syntax?
#include <iostream> #include <vector> using namespace std;
I am stuck with how to make a circular queue that are based on a struct. Have been reading about the implementation but cant really understand it fully. Here is what i got so far.
Code: #define SIZE 10 typedef struct { char reg; char brand; int modelyear; int mileage;
I've been making a project that requires different files to have access to objects declared in other files such that circular dependencies are created. I've done some research and discovered that pointers and forward declarations should be able to fix this.
Example:
File 1 declares variable x, must edit x and y
File 2 must edit x and y, declares variable y
I know this isn't the best example, as you could probably declare x and y in the same file, but please suffice it to say that I'm unable to do that in my project.
I have this program. I am trying to do this Circular List but i think something going wrong. The first of all is the list.The second is if my code for delete and select function are correct and the third i would like my program getting a "n" number of names and then make the circural list then print it and then when i select a number delete every node until give us the only one left.
Now the problem is in the core 1. Here I am unable to read the values from the specific memory location. I am getting garbage value. Where I am doing some stupid error.. I did not understand
Code: (front->ptr) = (unsigned int *) memory_location;
When I print the (front->ptr) it shows correct memory address but inside the De-queue function in core 1, I am getting wrong value..
Code: int deq(int buf[n]) { front1 = front; printf("Val %d ", front->info); // showing wrong value if (front1 == NULL) { printf("
Error: Trying to display elements from empty queue"); return 0;
