template class instantiation in another class in c++ - c++

Question

I have a template class that when I instantiate in main doesn't have any issues but when i try instantiating the same in another class is giving issues. can someone please enlighten me on the solution for this
#include<iostream>
#include<string>
using namespace std;
template <class T>
class property {
public:
property(string name)
{
propertyName= name;
}
private:
T item;
string propertyName;
};
main()
{
property<int> myIntProperty("myIntProperty");
}
the above code compiles with out any issue.
but
#include<iostream>
#include<string>
using namespace std;
template <class T>
class property {
public:
property(string name)
{
propertyName= name;
}
private:
T item;
string propertyName;
};
class propertyHolder
{
property<int> myIntProperty("myIntProperty");
};
this code is not getting compiled.
giving me error like
main.cpp|19|error: expected identifier before string constant|
main.cpp|19|error: expected ',' or '...' before string constant|
Thanks,
Harish

Answer 1

property<int> myIntProperty("myIntProperty");
This is a function declaration, so it expects you to insert a default argument after identifying it, like string s = "myIntProperty".
Perhaps you want to initialize an object called myIntProperty,
property<int> myIntProperty {"myIntProperty"};
This can be done in C++11, but you can also initialize it in the constructor initializer list,
// Header
class propertyHolder {
public:
propertyHolder( string s );
private:
property<int> myIntProperty;
};
// Source
propertyHolder::propertyHolder( string s ) :
myIntProperty( s )
{
}

Answer 2

You wanted to declare field in class propertyHandler. That syntax is not working because you cannot declare a field and assing it value at the same spot.
You can delcare it, and initialise in constructor:
property<int> myIntProperty;
propertyHolder(): myIntProperty("name") {}
or with c++11 syntax:
property<int> myIntProperty{"name"};
or declare it static, and them declare like that:
static property<int> myIntProperty;
and after class declaration:
property<int> propertyHolder::myIntProperty("name");