How would one add a template constructor to the class so that copy initialization from complex to complex is performed explicitly and without ambiguity? Is there a solution that is compiler and C version/standard agnostic? Is there an approach that only requires definition of a constructor without an additional operator overload?
I included the template copy constructor and operator overload (last two methods defined in the class) but the compiler gives me the following message.
Compilation error
main.cpp: In function ‘void testTemplateConstructor()’:
main.cpp:74:27: error: conversion from ‘complex<float>’ to ‘complex<double>’ is ambiguous
complex<double> cd = cf;
^~
main.cpp:35:5: note: candidate: complex<T>::operator complex<X>() [with X = double; T = float]
operator complex<X>(){
^~~~~~~~
main.cpp:29:5: note: candidate: complex<T>::complex(complex<X>&) [with X = float; T = double]
complex(complex<X>& arg) {
^~~~~~~
This is the test case being utilized.
void testTemplateConstructor() {
complex<float> cf{1.0f, 2.0f};
complex<double> cd = cf;
Assert(cf.real()==cd.real(), "Real parts are different.");
Assert(cf.imag()==cd.imag(), "Imaginary parts are different.");
}
template <typename T> class complex{
private:
typedef complex<T> complexi;
T real_;
T imag_;
public:
complex(){
real_ = 0;
imag_ = 0;
}
complex(T a, T b){
real_ = a;
imag_ = b;
}
complex(T a){
real_ = a;
}
complex(complex<T>& comp){
real_ = comp.real_;
imag_ = comp.imag_;
}
template <typename X>
complex(complex<X>& arg) {
real_ = arg.real_;
imag_ = arg.imag_;
}
template <typename X>
operator complex<X>(){
return complex<T>();
}
};
CodePudding user response：
so that copy initialization from complex to complex is performed explicitly and without ambiguity? Is there a solution that is compiler and C version/standard agnostic?
Yes, in this particular example, you can add a low level const to the parameter of the ctors.
template <typename T> class complex{
public:
typedef complex<T> complexi;
T real_;
T imag_;
public:
complex(){
real_ = 0;
imag_ = 0;
}
complex(T a, T b){
real_ = a;
imag_ = b;
}
complex(T a){
real_ = a;
}
complex(const complex<T>& comp){
std::cout<<"nornal version";;
real_ = comp.real_;
imag_ = comp.imag_;
}
template <typename X>
complex(const complex<X>& arg) {
std::cout<<"template version";;
real_ = arg.real_;
imag_ = arg.imag_;
}
};
void testTemplateConstructor() {
complex<float> cf{1.0f, 2.0f};
complex<double> cd = cf;
}