C++ Template Class with Template Constructor

Question

I tried to implement Properties in c++. I don't no why but if I want to compile my code there are quite a lot of errors. The main Idea was, that a template class and the tamplate constructor will give the requirement Informations.

I would be grateful if somebody could help me!

Compiling Message:

pi@raspberrypi ~/dev/property $ gcc -std=c++0x -o PropertyTest2 PropertyTest2.cpp
PropertyTest2.cpp:22:16: error: expected ‘;’ at end of member declaration
PropertyTest2.cpp:22:19: error: expected unqualified-id before ‘<’ token
PropertyTest2.cpp: In function ‘int main()’:
PropertyTest2.cpp:34:20: error: use of deleted function ‘PropertyTestClass::PropertyTestClass()’
PropertyTest2.cpp:8:7: error: ‘PropertyTestClass::PropertyTestClass()’ is implicitly deleted because the default definition would be ill-formed:
PropertyTest2.cpp:8:7: error: no matching function for call to ‘Property<int>::Property()’
PropertyTest2.cpp:8:7: note: candidates are:
Property4.cpp:21:2: note: template<int (** G)(), void (** S)(int&)> Property::Property()
Property4.cpp:6:7: note: constexpr Property<int>::Property(const Property<int>&)
Property4.cpp:6:7: note:   candidate expects 1 argument, 0 provided
Property4.cpp:6:7: note: constexpr Property<int>::Property(Property<int>&&)
Property4.cpp:6:7: note:   candidate expects 1 argument, 0 provided
PropertyTest2.cpp:38:20: error: no matching function for call to ‘Property<int>::Set(int)’
PropertyTest2.cpp:38:20: note: candidate is:
Property4.cpp:30:7: note: void Property<T>::Set(T&) [with T = int]
Property4.cpp:30:7: note:   no known conversion for argument 1 from ‘int’ to ‘int&’

Property Class (Property.cpp)

#ifndef __PROPERTY_FH__
#define __PROPERTY_FH__


template <class T>
class Property {
private:
    typedef T (*TGetter)(void);
    typedef void (*TSetter)(T &);

    TGetter Getter;
    TSetter Setter;


public:
    typedef T type;

    template<TGetter *G,
             TSetter *S
            >
    Property() {
        this->Getter = G;
        this->Setter = S;
    }

    T Get(void) {
        return (this->Getter)();
    }

    void Set(T &value) {
        (this->Setter)(value);
    }
};

#endif

Testing file (PropertyTest.cpp):

#ifndef __PROPERTY_TEST_FH__
#define __PROPERTY_TEST_FH__

#include <iostream>
#include "Property.cpp"


class PropertyTestClass {
private:
    // ReadWrite Property for age
    int _age;
    int AgeGetter(void) {
        return this->_age;
    }
    void AgeSetter(int &value) {
        this->_age = value;
    }


public:
    // ReadWrite Property for age
    Property<int> age<&PropertyTestClass::AgeGetter, &PropertyTestClass::AgeSetter>;
};

#endif


/**
 * Program Entry
**/
int main() {
    std::cout << "Property Test Programm\n\n";

    PropertyTestClass propTest;


    std::cout << "ReadWrite Property for age\n";
    propTest.age.Set(5);
    std::cout << propTest.age.Get() << "\n";


    return 0;
}

First, `TGetter` and `TSetter` are not defined in `Property.cpp`. Second, that file should not have the extension `.cpp`. Your compiler/IDE might try to compile it by itself. — juanchopanza, Jan 19 '14 at 17:20
Possible duplicate of http://stackoverflow.com/questions/2861839/can-the-template-parameters-of-a-constructor-be-explicitly-specified — Constructor, Jan 19 '14 at 17:38
Don't use `(void)` for zero parameters functions, just use `()`. `(void)` is there for C compatibility only. — Manu343726, Jan 19 '14 at 18:51

score 0 · Accepted Answer · answered Jan 19 '14 at 18:37

Ok, this time fixed all the problems in your code.

Property.cpp:

#ifndef __PROPERTY_FH__
#define __PROPERTY_FH__

#include <boost/function.hpp>

template <class T>
class Property {
private:

    typedef boost::function <T()> TGetter;
    typedef boost::function <void(const T&)> TSetter;

    TGetter Getter;
    TSetter Setter;


public:
    typedef T type;

    Property(TGetter G, TSetter S) {
        this->Getter = G;
        this->Setter = S;
    }

    T Get(void) {
        return (this->Getter)();
    }

    void Set(const T &value) {
        (this->Setter)(value);
    }
};

#endif

PropertyTests.cpp:

#ifndef __PROPERTY_TEST_FH__
#define __PROPERTY_TEST_FH__

#include <iostream>
#include <boost/bind.hpp>
#include "Property.cpp"


class PropertyTestClass {
private:
    // ReadWrite Property for age
    int _age;
    int AgeGetter() {
        return this->_age;
    }
    void AgeSetter(const int &value) {
        this->_age = value;
    }


public:
    // ReadWrite Property for age
    Property<int> age;
    PropertyTestClass() : age(
        boost::bind(&PropertyTestClass::AgeGetter, this),
        boost::bind(&PropertyTestClass::AgeSetter, this, _1))
    {}
};

#endif


/**
 * Program Entry
**/
int main() {
    std::cout << "Property Test Programm\n\n";

    PropertyTestClass propTest;


    std::cout << "ReadWrite Property for age\n";
    propTest.age.Set(5);
    std::cout << propTest.age.Get() << "\n";


    return 0;
}

Output:

$ ./a.out 
Property Test Programm

ReadWrite Property for age
5

Thank you very much. Now I understand what you mean. – Heinrich Jan 19 '14 at 19:37 — Heinrich, Jan 19 '14 at 19:37

C++ Template Class with Template Constructor

1 Answers1