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6.21.3.6 Standard option types

`optparse` has six built-in option types: `string`, `int`, `long`, `choice`, `float` and `complex`. If you need to add new option types, see section , Extending `optparse`.

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.