C/C++: Using `extern const` in header files to make global variables read only

I was experimenting with GCC and found out that you can declare variables const in header files but keep them mutable in implementation files.

header.h:

#ifndef HEADER_H_
#define HEADER_H_

extern const int global_variable;

#endif

header.c:

int global_variable = 17;

This makes global_variable modifiable to the implementation but const to every file that includes header.h.

#include "header.h"

int main(void)
{
    global_variable = 34; /* This is an error and will not compile! */
    return 0;
}

Is this technique used in practise?

People often recommend using get-functions to retrieve global state when building interfaces in C. Are there any advantages to that approach over this?

To me this approach seems to be a lot more clearer and does not have the added overhead of a function call each time someone tries to access global_variable.