Struct core::fmt::rt::Argument

pub struct Argument<'a> {
    value: &'a Opaque,
    formatter: fn(_: &Opaque, _: &mut Formatter<'_>) -> Result,
}

🔬This is a nightly-only experimental API. (fmt_internals)

This struct represents the generic “argument” which is taken by format_args!(). It contains a function to format the given value. At compile time it is ensured that the function and the value have the correct types, and then this struct is used to canonicalize arguments to one type.

Argument is essentially an optimized partially applied formatting function, equivalent to exists T.(&T, fn(&T, &mut Formatter<'_>) -> Result.

Fields

value: &'a Opaque

🔬This is a nightly-only experimental API. (fmt_internals)

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

🔬This is a nightly-only experimental API. (fmt_internals)

Implementations

impl<'a> Argument<'a>

fn new<'b, T>( x: &'b T, f: fn(_: &T, _: &mut Formatter<'_>) -> Result ) -> Argument<'b>

🔬This is a nightly-only experimental API. (fmt_internals)

pub fn new_display<'b, T: Display>(x: &'b T) -> Argument<'_>

🔬This is a nightly-only experimental API. (fmt_internals)

pub fn new_debug<'b, T: Debug>(x: &'b T) -> Argument<'_>

🔬This is a nightly-only experimental API. (fmt_internals)

pub fn new_octal<'b, T: Octal>(x: &'b T) -> Argument<'_>

🔬This is a nightly-only experimental API. (fmt_internals)

pub fn new_lower_hex<'b, T: LowerHex>(x: &'b T) -> Argument<'_>

🔬This is a nightly-only experimental API. (fmt_internals)

pub fn new_upper_hex<'b, T: UpperHex>(x: &'b T) -> Argument<'_>

🔬This is a nightly-only experimental API. (fmt_internals)

pub fn new_pointer<'b, T: Pointer>(x: &'b T) -> Argument<'_>

🔬This is a nightly-only experimental API. (fmt_internals)

pub fn new_binary<'b, T: Binary>(x: &'b T) -> Argument<'_>

🔬This is a nightly-only experimental API. (fmt_internals)

pub fn new_lower_exp<'b, T: LowerExp>(x: &'b T) -> Argument<'_>

🔬This is a nightly-only experimental API. (fmt_internals)

pub fn new_upper_exp<'b, T: UpperExp>(x: &'b T) -> Argument<'_>

🔬This is a nightly-only experimental API. (fmt_internals)

pub fn from_usize(x: &usize) -> Argument<'_>

🔬This is a nightly-only experimental API. (fmt_internals)

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

🔬This is a nightly-only experimental API. (fmt_internals)

pub(super) fn as_usize(&self) -> Option<usize>

🔬This is a nightly-only experimental API. (fmt_internals)

pub fn none() -> [Self; 0]

🔬This is a nightly-only experimental API. (fmt_internals)

Used by format_args when all arguments are gone after inlining, when using &[] would incorrectly allow for a bigger lifetime.

This fails without format argument inlining, and that shouldn’t be different when the argument is inlined:

let f = format_args!("{}", "a");
println!("{f}");

Trait Implementations

impl<'a> Clone for Argument<'a>

fn clone(&self) -> Argument<'a>

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<'a> Copy for Argument<'a>