[C++] Coding convention - prefix k and What

• trace Android code時, 常會看到如下的 code

•     enum {
          kWhatSetDataSource              = '=DaS',
          kWhatPrepare                    = 'prep',
          kWhatSetVideoSurface            = '=VSu',
          kWhatSetAudioSink               = '=AuS',
          kWhatMoreDataQueued             = 'more',
          kWhatConfigPlayback             = 'cfPB',
          ...
  

• 這個 k代表什麼意思呢? => konstant, 因為 c的 prefix 已經被 char 用掉了, 用了 Germany的 konstant, 至於全大寫與 Hungarian notation 就不在這戰了
• 至於 What, 則猜測這些 enum 主要是用來在 message中傳遞, 對應 message.what 的 int值, 所以在 handler中常會看到自行定義的 enum 用 kWhat當 prefix
• 節錄 Android doc Message.what

• what
  int what
  User-defined message code so that the recipient can identify what this message is about. 

Each Handler has its own name-space for message codes, 

so you do not need to worry about yours conflicting with other handlers.

• Reference:
• Where does the k prefix for constants come from?