Templates(Chapter 13 of The C++ Programming Language)

　　[1] Use templates to express algorithms that apply to many argument types; 

　　[2] Use templates to express containers; 

　　[3] Provide specializations for containers of pointers to minimize code size; 

　　[4] Always declare the general form of a template before specializations; 

　　[5] Declare a specialization before its use; 

　　[6] Minimize a template definition’s dependence on its instantiation contexts;

　　[7] Define every specialization you declare; 

　　[8] Consider if a template needs specializations for C-style strings and arrays; 

　　[9] Parameterize with a policy object; 

　　[10] Use specialization and overloading to provide a single interface to implementations of the same concept for different types; 

　　[11] Provide a simple interface for simple cases and use overloading and default arguments to express less common cases; 

　　[12] Debug concrete examples before generalizing to a template; 

　　[13] Remember to e x p o r t template definitions that need to be accessible from other translation units; 

　　[14] Separately compile large templates and templates with nontrivial context dependencies; 

　　[15] Use templates to express conversions but define those conversions very carefully;

　　[16] Where necessary, constrain template arguments using a constraint() member function;

　　[17] Use explicit instantiation to minimize compile time and link time;

　　[18] Prefer a template over derived classes when runtime efficiency is at a premium;

　　[19] Prefer derived classes over a template if adding new variants without recompilation is important;

　　[20] Prefer a template over derived classes when no common base can be defined; 

　　[21] Prefer a template over derived classes when built-in types and structures with compatibility constraints are important;