optparse has six built-in option types: string, int, long,
choice, float and complex. If you need to add new option
types, see section
Arguments to string options are not checked or converted in any way: the text on the command line is stored in the destination (or passed to the callback) as-is.
Integer arguments are passed to int() to convert them to Python
integers. If int() fails, so will optparse, although with a more
useful error message. (Internally, optparse raises OptionValueError;
OptionParser catches this exception higher up and terminates your
program with a useful error message.)
Likewise, float arguments are passed to float() for conversion,
long arguments to long(), and complex arguments to
complex(). Apart from that, they are handled identically to integer
arguments.
choice options are a subtype of string options. The choices
option attribute (a sequence of strings) defines the set of allowed
option arguments. optparse.check_choice() compares
user-supplied option arguments against this master list and raises
OptionValueError if an invalid string is given.
See About this document... for information on suggesting changes.