Template issue causes linker error (C++) [duplicate]

by

You have to have your template definitions available at the calling site. That means no .cpp files.

The reason is templates cannot be compiled. Think of functions as cookies, and the compiler is an oven.

Templates are only a cookie cutter, because they don’t know what type of cookie they are. It only tells the compiler how to make the function when given a type, but in itself, it can’t be used because there is no concrete type being operated on. You can’t cook a cookie cutter. Only when you have the tasty cookie dough ready (i.e., given the compiler the dough [type])) can you cut the cookie and cook it.

Likewise, only when you actually use the template with a certain type can the compiler generate the actual function, and compile it. It can’t do this, however, if the template definition is missing. You have to move it into the header file, so the caller of the function can make the cookie.

More Related Contents:

  1. “Undefined reference to” template class constructor [duplicate]
  2. “not declared in this scope” error with templates and inheritance [duplicate]
  3. Deciphering C++ template error messages
  4. SFINAE tried with bool gives compiler error: “template argument ‘T::value’ involves template parameter” [duplicate]
  5. Is it possible to pass a class as an argument of a function in C++
  6. Why do I have to access template base class members through the this pointer?
  7. Officially, what is typename for?
  8. Splitting templated C++ classes into .hpp/.cpp files–is it possible?
  9. Non-type template parameters
  10. Why C++ containers don’t allow incomplete types?
  11. What exactly is the “immediate context” mentioned in the C++11 Standard for which SFINAE applies?
  12. Why is the template argument deduction not working here?
  13. How does this template magic determine array parameter size?
  14. Specifying one type for all arguments passed to variadic function or variadic template function w/out using array, vector, structs, etc?
  15. using std::is_same, why my function still can’t work for 2 types
  16. How to write a type trait `is_container` or `is_vector`?
  17. Template partial ordering – why does partial deduction succeed here
  18. Matching alias template as template argument
  19. multiple definition of template specialization when using different objects
  20. Undefined reference error for template method [duplicate]
  21. How do compilers treat variable length arrays
  22. Templated class specialization where template argument is a template
  23. C++: How to require that one template type is derived from the other
  24. c++ –
  25. How does the linker handle identical template instantiations across translation units?
  26. C++ std::map holding ANY type of value
  27. details of std::make_index_sequence and std::index_sequence
  28. ‘auto’ as a template argument placeholder for a function parameter
  29. Calculating and printing factorial at compile time in C++
  30. Passing a lambda into a function template

Leave a Comment