Passing parameters to template constructor [duplicate] - c++

Question

This question already has an answer here:
Why class data members can't be initialized by direct initialization syntax?
(1 answer)
Closed 2 years ago.
In C++ I am having trouble passing parameters to the constructor for a template class.
it works when I instantiate from a function; but if I instantiate from a class, it gives "error C2059: syntax error: 'string'"
this is my very trimmed down example (names have been changed to protect the incent).
I am currently have std:latest enabled in Visual Studio 2019 and I've tried in 2017 as well.
#include <string>
#include <iostream>
template <class T>
class cap
{
public:
cap() : p(new(T)) {}
cap(const std::string& sfile, const std::string& sfunc, int line)
: m_file(sfile), m_func(sfunc), m_line(line) {}
~cap() {
delete p;
std::cout << "object freed: created in " << m_func << " line " << m_line << " of " << m_file;
}
private:
T* p{nullptr};
std::string m_file;
std::string m_func;
int m_line{0};
};
void foo()
{
cap<int> foo1("file", "func", 5); //<< compiles okay
}
class bar
{
cap<int> foo1("file", "func", 5); //<< "syntax error: 'string'"
};
IntelliSense says "expected a type specifier" when I hover the params used inside the class
My end goal is to have a macro to instantiate the object; passing in the location in source.The object thus knows where it was created.
#define CAP(type,var) cap<type> var(__FILE__, __func__, __LINE__)
CAP(somestruct, myvar);
// expands to:
cap<somestruct> myvar("file.cpp", "myfunc", 50);

Answer 1

For in-class initialization use the uniform initialization:
class bar
{
cap<int> foo1{"file", "func", 5};
};
#Alan has already provided a reference for why direct initialization using () don't work. It's also known as the C++ most vexed parse.