Trait MessageOption

pub trait MessageOption {
    // Required methods
    fn number(&self) -> u16;
    fn value(&self) -> &[u8];

    // Provided methods
    fn value_str(&self) -> Option<&str> { ... }
    fn value_uint<U>(&self) -> Option<U>
       where U: Unsigned + FromBytes,
             U::Bytes: Sized + Default { ... }
}

Iteration item for option values

This is the trait of items produced by ReadableMessage::options().

An implementation needs to allow the user to get the value as a memory slice. This is trivial for messages that are stored in serialized form; there this can be a fat pointer. Implementations that store options semantically (eg. as a struct Block { n: usize, m: bool, szx: u8 }) will typically make their MessageOption large enough to contain serialized options, or heap-allocate for them.

Required Methods

fn number(&self) -> u16

Numeric option number

See OptionNumber on how to interpret them.

fn value(&self) -> &[u8]

Obtain the option’s raw value

This can be used directly for options with opaque value semantics; for other semantics, see the value_str and value_uint helper methods.

Provided Methods

fn value_str(&self) -> Option<&str>

Obtain the option’s value as a text string, or None if the option contains invalid UTF-8.

Implementations can override this to reduce the string checking overhead if they already have the value as a string internally.

fn value_uint<U>(&self) -> Option<U>

where U: Unsigned + FromBytes, U::Bytes: Sized + Default,

Obtain the option’s value as a number following the uint value format, or None if the option is too long for the requested number size.

Implementations can override this to reduce conversion overhead if they already have a numeric value internally as soon as U’s type is replaced with an equally capable public num trait.

Dyn Compatibility

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.

Implementors