[ANSWERED] Overloading the << operator for conducting checks before output to STDOUT

Question

I am trying to make a Button Class to print certain boxes on a text based console window in Windows that may be interfaced with by the user by actions like hovering on it, clicking it, etc. I also made a Console class to handle console properties like Size, Foreground and Background Text Colors, Cursor Positions for Printing, etc. Now, I want to prevent the << operator to print on the button or any such element. So, I created a vector of 4 points to store the area of the Button and tried to overload << to check before output that the current cursor position does not lie on the buttons :

template <typename T> std::ostream& operator<<(std::ostream& os, T obj)
{
// SMALL_RECT is a struct of 4 points. Console::Reserved() returns the vector with all
// the saved area points.
std::vector<SMALL_RECT> Res = Console::Reserved();
CONSOLE_SCREEN_BUFFER_INFO cb;
GetConsoleScreenBufferInfo(Console::Out(),&cb); COORD c = cb.dwCursorPosition;
for(SMALL_RECT s : Res)
{
if((c.X>=s.Left||c.X<=s.Right)||(c.Y>=s.Top||c.Y<=s.Right))
throw std::logic_error(">> Console : Space reserved for UI Element!");
}
os<<obj; return os;
}

However, the overload failed, as when I tried printing a single character somewhere else on the console, I got a lot of errors, like the following :

error: ambiguous overload for 'operator<<' (operand types are 'std::ostream {aka std::basic_ostream<char>}' and 'const unsigned char')
error: ambiguous overload for 'operator<<' (operand types are 'std::ostream {aka std::basic_ostream<char>}' and 'std::__cxx11::string {aka std::__cxx11::basic_string<char>}')

Why do these errors occur? Is there a solution? If not, is there another way I can achieve a similar result?

Answer 1

I think David Rodriguez's answer, ( the second answer ) here is a good explanation as to why the ambiguity is triggered.
https://stackoverflow.com/questions/5319190/ambiguous-overload-for-operator-in-stdcout

You could make a wrapper which temporarily holds the value and write the operator<< overload for that wrapper which does the appropriate checks and then calls the temporarily holded values' operator<<. No ambiguity there.

Or you could scrap the operator<< entirely and go for a Console::Write function or something.

Anyway here is kinda the idea:
#include <iostream>

template<typename T>
struct wrapper
{
const T& obj;

template<typename U>
friend std::ostream& operator<<( std::ostream& os, const wrapper<U>& o );
};

template<typename U>
std::ostream& operator<<( std::ostream& os, const wrapper<U>& o )
{
if( 0 )
throw std::logic_error( "Blablabla" );

return os << o.obj;
}

int main()
{
wrapper<char> w{ 'T' };
std::cout << w;
}

Answer 2

Dennis Thank you very much for answering my question. I'll try this approach and let you know.

Edit : The wrapper approach worked for me. Thanks a lot.