Редактирование: Binary flags (раздел)

=== Setting a bitflag ===

Above we did the following:

  var/f = 255 //0b11111111
  v3 = c & f

What happened was that completely irrespective of what c was, v3 became 0b11111111, since anything OR 1 = 1.

But we don't have to have the entire row of ones. What if we just add a single 1 in there. After all 0 OR anything = anything. The 0 doesn't change the value.

So let's write a proc, where ''dis'' is the disability we want to add (DISABILITY_EYE, DISABILITY_EAR, etc):

  mob/proc/add_disability(var/dis)
    disabilities = disabilities | dis

So if disabilities were 0b0000 before we called it, and we called it with DISABILITY_EAR, which is 2, we would get the following calculation

calling M.add_disability(DISABILITY_EAR)

disabilities = 0b0000 | 0b0010

     0b0000
  OR 0b0010
   = 0b0010

So the ''disabilities'' variable now becomes 0010, which indicates it has the poor hearing disability. But what if we called the same proc again, with the same argument DISABILITY_EAR, would anything change?

calling M.add_disability(DISABILITY_EAR)

disabilities = 0b0010 | 0b0010

     0b0010
  OR 0b0010
   = 0b0010

Nope. It remains the same, as it should.

And if we want to add another leg disability (DISABILITY_LEG)?

calling M.add_disability(DISABILITY_LEG)

disabilities = 0b0010 | 0b0100

     0b0010
  OR 0b0100
   = 0b0110

The old ear disability remains untouched, and the new leg disability is added.