C++ :: Declaration Of Template Specialized Classes

Aug 12, 2014

class intClass{};
class stringClass{};

template <typename T>
class Mediator {
// bunch of code
};

I want Mediator<int> to declare intClass friend, Mediator<std::string> to declare stringClass friend etc..., without having to redefine the entire specialization

template<>
Mediator<int>::friend intClass;

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C++ :: Template With A Specialized Template Class Parameter?

Nov 2, 2014

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;

[Code].....

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C++ :: Calling Method Of Specialized Template Base Class In Subclass

Feb 10, 2013

class IFoo {
virtual void Bar() = 0;
};

class FooAbstract {
virtual void Bar() {}

[Code] .....

How to call the Bar() method from FooTemplate in FooDerived::Bar()?

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C++ ::  typedef As Data Type For Specialized Template Function In Class From Shared Library

Jul 19, 2013

I have a class "Result" with a single template function Set(const std::string& arName, T& val) and a specialization of this function Set<Real>(const std::string& arName, Real& val) where Real is a typedef for double. The class is in a shared library and I use it in my main program. If I do result->Set<GLOBAL::Real>("U", 100.0); the wrong template function is called!

I check this by the output with std::cout.

Maybe it's a problem with the typedef.

If I link the object file of the Result class directly to my main program (no shared library), it works.

typedefs.hpp:
namespace GLOBAL {
typedef double Real;
} results.hpp
#include <iostream>

[Code] ....

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Visual C++ :: Vendor Classes - Conflicting Declaration Of Objects

Jan 22, 2013

The Light and Fan are two different vendor classes and they are not derived from any base class. I am trying to implement the Command design pattern but with generic implementation, so it should work in future with any new vendor class like Door, Window etc without much change in client code. I have thought about a Factory method but it will not work because it needs a Base class. I am trying to learn the design patterns.

Light *myobj;
Fan *myobj;
int choice;
cout<<"Select Light (1): ";
cout<<"Select Fan (2): ";

[Code] ....

Error:conflicting declaration 'Fan*myobj'

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C++ :: Object And Classes - Declaration Of Variable Using User Defined Type

Mar 17, 2013

I am getting a compilation error from the code below. It is when i am naming a variable with my user defined type.

#include<iostream>
#include<cstring>
#include<cstdlib>
using namespace std;
class person {

[Code] .....

C:Dev-CppTRIAL.PASS.!!!.cpp In function `int main()':
66 C:Dev-CppTRIAL.PASS.!!!.cpp expected primary-expression before "p"
66 C:Dev-CppTRIAL.PASS.!!!.cpp expected `;' before "p"
74 C:Dev-CppTRIAL.PASS.!!!.cpp `p' undeclared (first use this function)
(Each undeclared identifier is reported only once for each function it appears in.)
83 C:Dev-CppTRIAL.PASS.!!!.cpp `X' undeclared (first use this function)

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C++ :: Use Of Template Classes In Other Template Classes

Jan 24, 2012

I'm trying to make a template class which holds a template list I made. The list consists of template nodes (another template class I made).

My problem is that in some places (not everywhere) the compiler says that I'm trying to access private members of the node's class.

For example, if I define my node like this:
template<class T>
class CoefNode {
private:
T coef;

[Code]....

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C++ :: Using Template Class - Unable To Match Function Definition To Existing Declaration

May 12, 2013

I am just learning using class template but I keep getting error unable to match function definition to an existing declaration

template <typename T>
class Homework {
private:
string name;
public:
template <typename T>
void SetName(T val);

[Code] ....

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C++ :: Template Classes And Inline Methods

Aug 17, 2012

I have a template class which defines a few heavy methods. For now, they are defined in the same .h file as the class definition, but i`d like to have them in a separate .cpp file.

A situation i find you describe in the FAQs arises: [URL] ....

Problem: the export keyword has been deprecated in c++0x, if i recall correctly, and has never been implemented in any of the compilers i am using (msvc, gcc).

#Including the the .cpp file after the class definition (as described in the second post of the FAQ) works.

another question: i have methods that dont use any template code. Can i somehow declare them as such? (more of an esthecial question, which would make it easier to distinguish between template and non.template code).

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C++ :: How To Prevent Someone Passing Classes To Function Template

Sep 13, 2013

Let say i have a following scenario:

a function like this.

Code:
template <typename T1>
print (T1 x){
cout << x << "
";
}

How do I prevent user passing a class or a structure or aanoter function to my function print. I mean i know if a wrong thing is passed that i'll get an error eventually but is there a way to explicitly check what has been passed. How is this done usually ?

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C++ :: Way To Restrict A Template-capture To Certain Types / Classes

Nov 16, 2014

I was creating a template and I realized that certain data-types/structs/classes would not be applicable to my template.This would cause bugs and errors if used incorrectly. Is there a way to restrict a template-capture to certain types/classes?

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C++ :: Two Classes Derived From Same Template Class And Operator

Mar 11, 2013

class A {
// is abstract
};

class B : public A {
// ...
};

[Code] ....
[Code] ....

main3.cpp: In member function ‘FooB& FooB::operator=(const FooC&)’:
main3.cpp:46:44: error: expected ‘(’ before ‘other’
main3.cpp:46:49: error: no matching function for call to ‘Foo<C>::Foo(const FooC&)’
main3.cpp:46:49: note: candidates are:
main3.cpp:19:2: note: Foo<T>::Foo() [with T = C]
main3.cpp:19:2: note: candidate expects 0 arguments, 1 provided
main3.cpp:16:25: note: Foo<C>::Foo(const Foo<C>&)
main3.cpp:16:25: note: no known conversion for argument 1 from ‘const FooC’ to ‘const Foo<C>&’

Is there any way to make it work?

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C++ :: Creating Template Of Array To Use For Classes Line And Point

Jun 14, 2012

I want to create template of of Array in order to have possibility use this template for classes Line and Point.

Code:
// Array.h
// Templated Array class containging Ts
#ifndef Array_H
#define Array_H
template <class T=double> class Array {

[Code] .....

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C++ :: Array Of Classes With Classes Inside

Oct 5, 2013

I have an array of (Student)classes created in Manager.h, which contains a new instance of class Name (name),(in Student.h)How would I go about accessing the SetFirstName method in Name.cpp if I was in a class Manager.cpp? I have tried using Students[i].name.SetFirstName("name");

// In Manager.h
#include"Student.h"
class Manager
{

[Code]....

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C++ ::  how To Declare Template Function Inside Template Class

Dec 5, 2013

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 ?

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C++ :: Use Of Class Template Requires Template Argument List

Nov 6, 2013

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>

[Code]....

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C++ :: Partial Template Specialization With Template Class

May 27, 2013

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.

Here is the example:

#include <stdio.h>
template<typename Type>
class Obj1 {
public:
void ID() { printf("Object 1, size = %zu

[Code] .....

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)?

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C++ ::  Writing A Function Template With Template Arguments?

Mar 14, 2014

I have a function:

template<class Iterator, class T>
void a(Iterator, Iterator, const T&);

and I want to be able to simplify calls to 'a' with calls like

a(someIteratableContainer);

instead of having to call:

a(someIteratableContainer.begin(), someIteratableContainer.end(), valueOfTheContainersElementType);

I also want to be able to generalize the function to handle any of the standard iteratable contains: array, vector, deque, whatever.

I was under the impression I could write:

template<template<class T> class U> a(U<T>& container) {
a(container.begin(), container.end(), g(T()));
}

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.

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C++ :: Use External Template With Template Specialization?

Nov 17, 2013

[URL]

#include <iostream>
struct Outer {
template<typename T>
void go() {
std::cout << Test<T>::f() << std::endl;

[Code] .....

I have tried several variants on this code to no avail. Outer is in a header, along with the extern template statements, and the specializations after main are in their own cpp file. Main is in a different cpp file.

What do have to do to make this work? I cannot bring the definitions of f() into the header, and they will be different for different template parameters. Ideally, I want Test to remain a private member of Outer, though this can change if it's the only option.

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C++ :: Passing Same Template Value To Two Different Template Functions

Dec 11, 2014

I have been trying to get a hang on templates. I have the two following functions that that could be consolidated in a single template function:

void Attractor::updateFamilies(FamiliesController *_tmp, int _counter){

center.x = ofGetWidth()/2;
center.y = ofGetHeight()/3;
attractorCounter = _counter;
if(attractorCounter == 1){

[Code] .....

NotesController and FamiliesController have the same parent. The thing that I'm trying to grasp with templates is that is could something like:

template<class TYPE>
void Attractor::updateData(TYPE* *_tmp, int _counter){
center.x = ofGetWidth()/2;
center.y = ofGetHeight()/3;
attractorCounter = _counter;

[Code] ....

And then have another template function declaration for all the attractor functions where I pass the same template value as in the first one.

As you can see, I'm calling another functions inside called attractors(_tmp). I know that one way around it could be to get rid of that function and just do all the logic inside of each if statement. Is there any way to pass the same template function parameter within a template function parameter?

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C++ :: Template Class With Template Members

Feb 9, 2015

I have a class like this

PHP Code:
template<class X>
class A {
  X m_x;
public:
    X* foo();
    X* bar();
    //others are not related to X
}; 

I would like to get rid of

PHP Code: template<class X> 

For class level but still use it for members. Like this

PHP Code:
class A {
  X m_x;
public:
    template<class X>
    X* foo();
    template<class X>
    X* bar();
    //others are not related to X
}; 

However, I am still stuck at

PHP Code: X m_x; 

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C++ :: Declare Template Type Object Inside Template Type Class Definition

Oct 12, 2013

Let me put it into the code snippet:

/**
This class build the singleton design pattern.
Here you have full control over construction and deconstruction of the object.
*/
template<class T>
class Singleton

[Code]....

I am getting error at the assertion points when i call to the class as follows:

osgOpenCL::Context *cxt = osgOpenCL::Singleton<osgOpenCL::Context>::getPtr();

I tried commenting assertion statements and then the debugger just exits at the point where getPtr() is called.

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C++ :: Vector Of Template In Template

Aug 29, 2014

Given:

#include <string>
template <class T>
class basic_container{

[Code] .....

is this possible:

#include "../basic_container/basic_container.hpp"
template <class T>
class container_vector{

[Code] .....

If not, what do I need to do to achieve my goal?

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C++ :: Using Same Declaration Value More Than Once

Oct 11, 2014

I am trying to make a menu program and was wondering if there is a way to declare something more than once without using a different word.

ex.

#include <iostream>
using namespace std;
double grams, ounces, inches, feet, meters; //units to convert
int choice; //menu choice
int main() {
cout << "Welcome to Measurement Converter" << endl;

[Code] .....

I dont really know how to explain it but im trying to use int choice to make choose a program from a simple list.

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C++ :: Different Array Declaration

Jan 7, 2013

I would like to know the difference between the following two forms of array declaration:

(1)double myArray[3] = {1.0, 2.0, 3.0};

(2)array<double,3> myArray = {1.0, 2.0, 3.0};

If I say the second one allows to use different functions like .begin(), am I right? Is there any other difference between these two declaration?

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C++ :: Using Declaration Within Name Space Scope

Mar 16, 2013

Can we use using declaration within name space scope? is it safe to use it?

I think we can use using declaration for class scope and function scope only.

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