Struct Settings

pub struct Settings { /* private fields */ }

Settings used to control the parsers behaviour.

Implementations

impl Settings

pub fn new() -> Self

Create a new settings object.

pub fn ignore_unknown_options(self) -> Self

Specify that unknown options should be silently ignored (by default, the first unknown option will generate an error).

pub fn ignore_unknown_posn_args(self) -> Self

Specify that unknown positional arguments should be silently ignored (by default, they will generate an error).

pub fn no_strict_options(self) -> Self

By default, arguments are parsed as they would be by getopt(3) whereby if an option is marked as requiring a value (Need::Argument) and the option is found on the command line, the next argument (whether it starts with a dash or not!) is “consumed” as the options argument.

However, when this setting is enabled, option values cannot start with a dash.

Advice

• If you want to your program to behave like the traditional getopt(3), leave this setting unset.
• If you need your program to accept an argument starting with a dash (for example, you have an option which could accept a negative number), you should leave this setting unset.
• If your program provides options and flags and you wish to minimse the chance of a flag (particularly a numeric flag such as -1 or -2) being interpreted as an options value, consider setting this option to disable support for option values starting with a dash.

Example

If a program accepts a flag (-f) and an option that requires an value (-r <value>) and the following command-line is specified to the program…

$ prog -r -f

… the outcome of the parse will depend on this setting:

• If no_strict_options=false (the default), the command line will be passed successfully and the r option (Arg) will be given the value “-f” and the f option (Arg) will be considered to not have been specified.

  Note:

  This is how the POSIX command line argument getopt(3) works.

• If no_strict_options=true, the parse will fail with the error Error::MissingOptArg since in this mode, option values may not begin with a dash so the -f is treated as the next argument meaning the user forgot to specify a value for the previous argument (-r), which is an error.

  Note:

  This is an alternative behaviour adopted by some modern command line argument parsers.

Trait Implementations

impl Clone for Settings

fn clone(&self) -> Settings

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Settings

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for Settings

fn default() -> Settings

Returns the “default value” for a type.

impl Ord for Settings

fn cmp(&self, other: &Settings) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

where Self: Sized,

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

where Self: Sized,

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Self

where Self: Sized,

Restrict a value to a certain interval.

impl PartialEq for Settings

fn eq(&self, other: &Settings) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl PartialOrd for Settings

fn partial_cmp(&self, other: &Settings) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

fn lt(&self, other: &Rhs) -> bool

Tests less than (for self and other) and is used by the < operator.

fn le(&self, other: &Rhs) -> bool

Tests less than or equal to (for self and other) and is used by the <= operator.

fn gt(&self, other: &Rhs) -> bool

Tests greater than (for self and other) and is used by the > operator.

fn ge(&self, other: &Rhs) -> bool

Tests greater than or equal to (for self and other) and is used by the >= operator.

impl Copy for Settings

impl Eq for Settings

impl StructuralPartialEq for Settings