Enum Part 

#[non_exhaustive]
pub enum Part<'p> {
    Text(&'p str),
    BidiIsolation(Isolation),
    Expression(ExpressionPart<'p>),
    Markup(MarkupPart<'p>),
    Fallback(FallbackSource<'p>),
}

A part of a formatted message. Concatenated, the parts are the string output.

Variants (Non-exhaustive)

Non-exhaustive enums could have additional variants added in future. Therefore, when matching against variants of non-exhaustive enums, an extra wildcard arm must be added to account for any future variants.

Text(&'p str)

Literal text.

BidiIsolation(Isolation)

A bidi isolation control (the Default Bidi Strategy).

Expression(ExpressionPart<'p>)

A formatted placeholder.

Markup(MarkupPart<'p>)

Markup (it writes no text).

Fallback(FallbackSource<'p>)

A placeholder that resolved to a fallback value: {source}.