Trait Expected

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

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

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

Formats the value using the given formatter.

Implementations on Foreign Types

impl Expected for &str

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

Implementors

impl<'de, T> Expected for T

where T: Visitor<'de>,