A simple plugin that "takes over" the menu item in Goto -> Switch File -> Switch Header/Implementation. Actually, it takes over the command that gets invoked by that menu item.
Just use Switch Header/Implementation like you normally would. That is, either from the menu item in Goto -> Switch File -> Switch Header/Implementation, or by its keybinding, whatever that may be.
For example, if your header file lives in
$project_path/include/awesome/foo.hpp
and your implementation file lives in
$project_path/lib/foo.cpp
then this plugin will actually do the switch.
When you're in folder mode (you have not opened a .sublime-project file),
then the plugin will traverse parent directories. A sanity limit of going up
three parent directories is in place. You can change this number in the
settings of the plugin, but do not make this number too high, or Sublime might
freeze.
If your code base looks like this:
$project_path/include/foo/bar.hpp
$project_path/include/foo/baz/bar.hpp
$project_path/src/bar.cpp
then switching from src/bar.cpp, you'll most likely end up in
include/foo/bar.hpp, as that's the first good match. This is the downside of
folder mode.
When you're in project mode (you have opened a .sublime-project file),
then the plugin will assume that the project file is at the root of the
directory, and the search will start there. All candidate files are collected,
and if there's more than one candidate file, a quick panel will pop up asking
you to select the correct file. From that point on the plugin will always
choose your selection for switching. This mode is much more powerful. Use the
power of the sublime project file.
The plugin might come up with false positives. For example, if your code base looks like this:
$project_path/include/awesome/foo.hpp
$project_path/include/awesome/bar/foo.hpp
$project_path/src/bar/foo.cpp
then switching from include/awesome/foo.hpp, it will open src/bar/foo.cpp.
But src/bar/foo.cpp is probably paired with include/awesome/bar/foo.hpp.