Discussion on: Bitmasks: A very esoteric (and impractical) way of managing booleans

I think you wrote an explanation of bitfields that is both accessible and in depth, well done.

I think that the best use case for bitfields/bitmasks are found where the various "flags" you toggle on and off are not independent of each other, but have some meaningful relationship, e.g. the values in the field are "additive" in a sense.

For example, log levels are considered additive by some applications: if you log at "info" level, then you also log "error" and "warn" level messages, this relationship between the different possible values is well captured by bitfields by representing the "lowest" value as the smallest value in the field:

enum LogLevel {
  Error = 0b0001,
  Warn = 0b0011,
  Info = 0b0111,
  Debug = 0b1111
}

setLogLevel(LogLevel.Info);

Then whatever is logging can decide whether to log a message or not based on whether the configured log level "has" the specified flag by using bitwise and (&) as you mentioned, or making a numeric comparison:

if (message.level <= this.highestLogLevel) {
  this.doLog(message);
}

Another example is configuring media "directions" (you can run into this with webrtc):

enum MediaDirection {
  Send = 0b01,
  Receive = 0b10,
  All = 0b11
}

In these cases, the values have some meaningful relationship with each other and using bitfields feels quite natural to me to represent these relationships.