Why does TFS use bitwise shifting in enums?

[rwxsu]

Hello,

I'm just curious to why TFS chooses to use bitwise shifting in enumerations?

E.g.:

enum itemAttrTypes : uint32_t {
    ITEM_ATTRIBUTE_NONE,
    ITEM_ATTRIBUTE_ACTIONID = 1 << 0,
    ITEM_ATTRIBUTE_UNIQUEID = 1 << 1,
    ITEM_ATTRIBUTE_DESCRIPTION = 1 << 2,
    ITEM_ATTRIBUTE_TEXT = 1 << 3,
    ITEM_ATTRIBUTE_DATE = 1 << 4,
    ITEM_ATTRIBUTE_WRITER = 1 << 5,
    ITEM_ATTRIBUTE_NAME = 1 << 6,
    ITEM_ATTRIBUTE_ARTICLE = 1 << 7,
    ITEM_ATTRIBUTE_PLURALNAME = 1 << 8,
    ITEM_ATTRIBUTE_WEIGHT = 1 << 9,
    ITEM_ATTRIBUTE_ATTACK = 1 << 10,
    ITEM_ATTRIBUTE_DEFENSE = 1 << 11,
    ITEM_ATTRIBUTE_EXTRADEFENSE = 1 << 12,
    ITEM_ATTRIBUTE_ARMOR = 1 << 13,
    ITEM_ATTRIBUTE_HITCHANCE = 1 << 14,
    ITEM_ATTRIBUTE_SHOOTRANGE = 1 << 15,
    ITEM_ATTRIBUTE_OWNER = 1 << 16,
    ITEM_ATTRIBUTE_DURATION = 1 << 17,
    ITEM_ATTRIBUTE_DECAYSTATE = 1 << 18,
    ITEM_ATTRIBUTE_CORPSEOWNER = 1 << 19,
    ITEM_ATTRIBUTE_CHARGES = 1 << 20,
    ITEM_ATTRIBUTE_FLUIDTYPE = 1 << 21,
    ITEM_ATTRIBUTE_DOORID = 1 << 22,
    ITEM_ATTRIBUTE_CUSTOM = 1U << 31
};

in enums.h.

 

[oen432]

Because items can have multiple attributes and by using bits you can save them in a single integer.

 

[averatec]

Because items can have multiple attributes and by using bits you can save them in a single integer.

and it easier to write e.g.: 1 << 22 (equals to 4194304)
each of these numbers is the power of two, so it allows to use it like a bit flag (O.3.8a — Bit flags and bit masks | Learn C++ (https://www.learncpp.com/cpp-tutorial/3-8a-bit-flags-and-bit-masks/))