C++ writing an assign procedure for a container - c++

Question

I have a container, a class, and I would like to provide it with a method assign like STL do.
class myclass {
public:
//...
template < typename InputIterator >
void assign(InputIterator first, InputIterator last);
// ...
private:
// ...
std::vector<int> mystlcont;
// ...
};
template < typename InputIterator >
myclass::assign(InputIterator first, InputIterator last) {
this->mystlcont.clear();
this->mystlcont.assign(first, last);
}
Ok. Well I compile, ok.
I use it now...
myclass m;
std::vector<int> vect;
vect.push_back(1);
vect.push_back(1);
vect.push_back(2);
vect.push_back(3);
vect.push_back(5);
vect.push_back(8);
vect.push_back(13);
m.assign(vect.begin(), vect.end()); // Line X
When calling function at line X, compiler returns a very very ugly error.
workflow_test.hpp: In function ‘void
middleware::WorkflowSerializationTest()’:
workflow_test.hpp:114: error: invalid
cast from type
‘__gnu_cxx::__normal_iterator
’ to type ‘middleware::TaskDescriptor*’
workflow_test.hpp:114: error: invalid
cast from type
‘__gnu_cxx::__normal_iterator
’ to type ‘middleware::TaskDescriptor*’
workflow_test is the file where I am calling the function assign, myclass repreents Workflow class in workflow.hpp and workflow.cpp... TaskDescriptor is the element in the vector (the type in the collection in myclass).
Do you know why this happens?
I suspect that there must be some operator to overload in my class to let this mechanism work correctly.... becaue it is not method implementation the problem, even if I write
template < typename InputIterator >
void myclass::assign(InputIterator first, InputIterator last) {
// NOTHING WRITTEN IN THE BODY
}
When called raises the same exact "exception".

Answer 1

What you have is not your own container, but rather container wrapper.
But I see only one problem with your code: your myclass::assign definition does not have a return type specified.
This code actually works for me:
#include <vector>
#include <algorithm>
#include <iostream>
class MyWrapper {
public:
template <typename InputIterator>
void assign(InputIterator first, InputIterator last);
const std::vector<int>& container() const { return container_m; }
private:
std::vector<int> container_m;
};
template <typename InputIterator>
void MyWrapper::assign(InputIterator first, InputIterator last)
{
container_m.assign(first, last);
}
template <typename T>
void print(const T& x)
{
std::cout << x << " ";
}
int main()
{
MyWrapper mw;
std::vector<int> vect;
vect.push_back(1);
vect.push_back(2);
vect.push_back(3);
vect.push_back(4);
vect.push_back(5);
vect.push_back(6);
vect.push_back(7);
mw.assign(vect.begin(), vect.end());
std::for_each(mw.container().begin(), mw.container().end(), print<int>);
}
Output:
1 2 3 4 5 6 7