# IDEs and header files

**URL:** https://discourse.cmake.org/t/ides-and-header-files/2665
**Category:** Code
**Tags:** gen:vs, gen:xcode
**Created:** [February 1, 2021, 4:47am UTC](https://discourse.cmake.org/t/ides-and-header-files/2665 "2021-02-01T04:47:17Z")
**Posts on this page:** 1
**Showing post:** 2

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### Author: ![Angew](https://discourse.cmake.org/user_avatar/discourse.cmake.org/angew/32/229_2.png) [@Angew](https://discourse.cmake.org/u/Angew)
#### Post date: [February 1, 2021, 8:40am UTC](https://discourse.cmake.org/t/ides-and-header-files/2665/2 "2021-02-01T08:40:40Z")

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`target_sources` adds source files to a target, just like `target_compile_options` adds compilation options to it etc.

With all these commands, `PRIVATE` means “this applies only to the target itself” and `PUBLIC` means “this applies both to the target itself and to anyone who links to it.”(1)

In other words, marking a source files as `PUBLIC` means “add this source file to this target and also to all targets which link to it.” In particular, it does _not_ mean “this header is intended for public consumption.”

So, it’s very rarely useful to mark a source file as `PUBLIC`, and I can’t think of a situation where it would make sense to do so for a _header_. In particular, note that it does _not_ give the consuming target any include-path access to the file.

As a rule of thumb, don’t mark source files as anything other than `PRIVATE`. If you do encounter a situation where you need to deviate from that, you will probably know it by just how extraordinary it is.

If you wanted to signal "`a.h` is a public API header of the library," you’d actually do that by setting the library’s `target_include_directories(a PUBLIC ...)` so that whoever links against `a` gets the correct paths to be able to do `#include "a.h"`.

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(1) And for completeness, `INTERFACE` means "this applies only to those who link against the target. So `PUBLIC` is the union of `PRIVATE` and `INTERFACE`.

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