This is a family of functions which return a specified attribute
value for an Object using one of several different data
types. The type is selected by replacing <X> in the function name
by C, D, F, I or L, to obtain a result in const char* (i.e. string),
double, float, int, or long format, respectively.
If possible, the attribute value is converted to the type you
request. If conversion is not possible, an error will result.