Trait Expected 

pub trait Expected {
    // Required method
    fn fmt(&self, formatter: &mut Formatter<'_>) -> Result<(), Error>;
}

Expected represents an explanation of what data a Visitor was expecting to receive.

This is used as an argument to the invalid_type, invalid_value, and invalid_length methods of the Error trait to build error messages. The message should be a noun or noun phrase that completes the sentence “This Visitor expects to receive …”, for example the message could be “an integer between 0 and 64”. The message should not be capitalized and should not end with a period.

Within the context of a Visitor implementation, the Visitor itself (&self) is an implementation of this trait.

fn visit_bool<E>(self, v: bool) -> Result<Self::Value, E>
where
    E: de::Error,
{
    Err(de::Error::invalid_type(Unexpected::Bool(v), &self))
}

Outside of a Visitor, &"..." can be used.

return Err(de::Error::invalid_type(
    Unexpected::Bool(v),
    &"a negative integer",
));

Required Methods

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

Format an explanation of what data was being expected. Same signature as the Display and Debug traits.

Trait Implementations

impl Display for dyn Expected + '_

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

Formats the value using the given formatter.

Dyn Compatibility

This trait is dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety".

Implementations on Foreign Types

impl Expected for &str

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

Implementors

impl<'de, T> Expected for T

where T: Visitor<'de>,