Re: [Bug-gnulib] Re: linebreak.c proposed patches for size-calculation overflows

[Paul Eggert]

James Youngman <address@hidden> writes:

> I normally use void* to discourage the user from fiddling with my
> data.

You can prevent the user from fiddling with your data with struct, if
you put something like this in your .h file:

  struct foo;
  int access_function (struct foo *p);

and then put something like this in the corresponding .c file:

  struct foo { int x; }
  int access_function (struct foo *p) { return p->x; }

The advantage of this approach (as opposed to void *) is the improved
type-checking: you catch more dumb mistakes (e.g.,
access_function("oops")) at compile-time.

You can combine this idea with the typedef idea, e.g., by putting this
in your header:

struct foo;
typedef struct foo *foo;
int access_function (foo p);