NAME
type_field - bit field used for optimizations

DESCRIPTION
Type fields are used by arrays, mappings and some svalue operations for optimization. The type field consists of OR:ed bits, one for each type. The bit for an array is 1<<T_ARRAY (same as BIT_ARRAY) The bit for a string is 1<<T_STRING (or BIT_STRING) etc.

A bit field never has to be exact, it needs to have at least those bits that are present in the operation. It is never harmful to have too many bits though. It seldom pays off to calculate the bit field explicitly, so if you don't know what types are involved you should use -1 for the type field.

KEYWORDS
data_types

SEE ALSO
mapping, array and svalue