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#include <iostream>
#include <fstream>
#include <vector>
 
class IReadable
{
public:
	IReadable(){};
	virtual ~IReadable(){};
	virtual IReadable& read(char *p,int n) = 0;
};
 
class CFileReader: public IReadable
{
public:
	template <class T>
	CFileReader(T& v) : obj(&v) {};
	~CFileReader(){};
	IReadable& read(char *p,int n) {
		this->obj->read(p,n);
		return *(this->obj);
	}
private:
	IReadable* obj;
};
 
class CMemoryReader
{
public:
	CMemoryReader(){};
	~CMemoryReader(){};
	CMemoryReader& read(char *p,int n) { return *this; }; // do nothing
private:
	char *mem;
};
 
int main(int argc,char **argv)
{
	std::ifstream file("foo.bar",std::ifstream::binary);
	CFileReader file_reader(&file);
	CMemoryReader memory_reader;
	std::vector<IReadable*> vv;
	vv.push_back(&file_reader);
	vv.push_back(&memory_reader);
	char buff[8];
 
	for(auto& reader : vv)
	{
		reader->read(buff,4);
	}
	return 0;
}
 

prog.cpp: In function ‘int main(int, char**)’:
prog.cpp:40:26: error: invalid initialization of non-const reference of type ‘std::basic_ifstream<char>*&’ from an rvalue of type ‘std::ifstream* {aka std::basic_ifstream<char>*}’
  CFileReader file_reader(&file);
                          ^~~~~
prog.cpp:17:2: note:   initializing argument 1 of ‘CFileReader::CFileReader(T&) [with T = std::basic_ifstream<char>*]’
  CFileReader(T& v) : obj(&v) {};
  ^~~~~~~~~~~
prog.cpp:44:29: error: no matching function for call to ‘std::vector<IReadable*>::push_back(CMemoryReader*)’
  vv.push_back(&memory_reader);
                             ^
In file included from /usr/include/c++/6/vector:64:0,
                 from prog.cpp:3:
/usr/include/c++/6/bits/stl_vector.h:914:7: note: candidate: void std::vector<_Tp, _Alloc>::push_back(const value_type&) [with _Tp = IReadable*; _Alloc = std::allocator<IReadable*>; std::vector<_Tp, _Alloc>::value_type = IReadable*]
       push_back(const value_type& __x)
       ^~~~~~~~~
/usr/include/c++/6/bits/stl_vector.h:914:7: note:   no known conversion for argument 1 from ‘CMemoryReader*’ to ‘IReadable* const&’
/usr/include/c++/6/bits/stl_vector.h:932:7: note: candidate: void std::vector<_Tp, _Alloc>::push_back(std::vector<_Tp, _Alloc>::value_type&&) [with _Tp = IReadable*; _Alloc = std::allocator<IReadable*>; std::vector<_Tp, _Alloc>::value_type = IReadable*]
       push_back(value_type&& __x)
       ^~~~~~~~~
/usr/include/c++/6/bits/stl_vector.h:932:7: note:   no known conversion for argument 1 from ‘CMemoryReader*’ to ‘IReadable*&&’

Standard output is empty