Trait tracing_subscriber::fmt::FormatFields[][src]

pub trait FormatFields<'writer> {
    fn format_fields<R: RecordFields>(
        &self,
        writer: &'writer mut dyn Write,
        fields: R
    ) -> Result; fn add_fields(
        &self,
        current: &'writer mut String,
        fields: &Record<'_>
    ) -> Result { ... } }
This is supported on crate feature fmt only.
Expand description

A type that can format a set of fields to a fmt::Write.

FormatFields is primarily used in the context of FmtSubscriber. Each time a span or event with fields is recorded, the subscriber will format those fields with its associated FormatFields implementation.

Required methods

Format the provided fields to the provided writer, returning a result.

Provided methods

Record additional field(s) on an existing span.

By default, this appends a space to the current set of fields if it is non-empty, and then calls self.format_fields. If different behavior is required, the default implementation of this method can be overridden.

Implementors