Forward Declaration
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Abstract
- In Graphics
- Reduce the number of cpp files that get recompiled when you touch a header file.
- This happens by moving the
#includefrom the header file to the source file. - The cpp file still gets recompiled when you touch the header file, but the circular dependency is broken.
Definition
- Not
#includeing in header files. - Example:
class Ship* ship;. - Instead, telling the compiler hey, I promise, there will be this class definition!
- This only works when referring to a pointer or reference
- When there is no need to construct
- Calling function requires
#include. - Virtual functions are irrelevant with a forward declaration.
Benefits
- Compile time improvements
- Resolves circular dependency
#pragma oncesolves circular dependency but does not resolve the order dependency.
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