C++ why the #include on the bottom of header for templates?

Question

If I have a program header file named program.h and a template named program.template, I learned that you need to #include "program.template" at the bottom of the program.h file before #endif. This seems inconsistent with previous methods of having #include on the top of the file. Why is this?

My other question is, do you need #include "program.h" in the program.template file? Why or why not? If so, on the top or on the bottom of the file?

Thanks!

Related: http://stackoverflow.com/questions/495021/why-can-templates-only-be-implemented-in-the-header-file — juanchopanza, Sep 21 '14 at 17:26
All `#include` does is basically copy-paste the file contents there. — chris, Sep 21 '14 at 17:41

score 1 · Answer 1 · answered Sep 21 '14 at 17:42

1

#include is a C/C++ preprocessor directive. It tells the compiler (pre processor component) to dump the contents of file X (e.g. a header file) into the source code of the current file at the #include location.

The #include directive can be used in many ways which require placing it at the start, end or the middle of another header/C/CPP file.

Without seeing your code, it's hard to tell what or why it was done.

answered Sep 21 '14 at 17:42

egur

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It is actually really simple to tell why it was done: `template` bodies usually need to be visible to consumers of said functions. – Yakk - Adam Nevraumont Sep 21 '14 at 18:33

C++ why the #include on the bottom of header for templates?

1 Answers1