Trait tor_hsservice::internal_prelude::Debug

1.0.0 · source ·

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

Expand description

? formatting.

Debug should format the output in a programmer-facing, debugging context.

Generally speaking, you should just derive a Debug implementation.

When used with the alternate format specifier #?, the output is pretty-printed.

For more information on formatters, see the module-level documentation.

This trait can be used with #[derive] if all fields implement Debug. When derived for structs, it will use the name of the struct, then {, then a comma-separated list of each field’s name and Debug value, then }. For enums, it will use the name of the variant and, if applicable, (, then the Debug values of the fields, then ).

§Stability

Derived Debug formats are not stable, and so may change with future Rust versions. Additionally, Debug implementations of types provided by the standard library (std, core, alloc, etc.) are not stable, and may also change with future Rust versions.

§Examples

Deriving an implementation:

#[derive(Debug)]
struct Point {
    x: i32,
    y: i32,
}

let origin = Point { x: 0, y: 0 };

assert_eq!(format!("The origin is: {origin:?}"), "The origin is: Point { x: 0, y: 0 }");

Manually implementing:

use std::fmt;

struct Point {
    x: i32,
    y: i32,
}

impl fmt::Debug for Point {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.debug_struct("Point")
         .field("x", &self.x)
         .field("y", &self.y)
         .finish()
    }
}

let origin = Point { x: 0, y: 0 };

assert_eq!(format!("The origin is: {origin:?}"), "The origin is: Point { x: 0, y: 0 }");

There are a number of helper methods on the Formatter struct to help you with manual implementations, such as debug_struct.

Types that do not wish to use the standard suite of debug representations provided by the Formatter trait (debug_struct, debug_tuple, debug_list, debug_set, debug_map) can do something totally custom by manually writing an arbitrary representation to the Formatter.

impl fmt::Debug for Point {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(f, "Point [{} {}]", self.x, self.y)
    }
}

Debug implementations using either derive or the debug builder API on Formatter support pretty-printing using the alternate flag: {:#?}.

Pretty-printing with #?:

#[derive(Debug)]
struct Point {
    x: i32,
    y: i32,
}

let origin = Point { x: 0, y: 0 };

assert_eq!(format!("The origin is: {origin:#?}"),
"The origin is: Point {
    x: 0,
    y: 0,
}");

Required Methods§

1.0.0 · source

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

Formats the value using the given formatter.

§Errors

This function should return Err if, and only if, the provided Formatter returns Err. String formatting is considered an infallible operation; this function only returns a Result because writing to the underlying stream might fail and it must provide a way to propagate the fact that an error has occurred back up the stack.

§Examples

use std::fmt;

struct Position {
    longitude: f32,
    latitude: f32,
}

impl fmt::Debug for Position {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.debug_tuple("")
         .field(&self.longitude)
         .field(&self.latitude)
         .finish()
    }
}

let position = Position { longitude: 1.987, latitude: 2.983 };
assert_eq!(format!("{position:?}"), "(1.987, 2.983)");

assert_eq!(format!("{position:#?}"), "(
    1.987,
    2.983,
)");

Trait tor_hsservice::internal_prelude::DebugCopy item path

§Stability

§Examples

Required Methods§

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

§Errors

§Examples

Implementors§

impl Debug for fs_mistrust::err::Error

impl Debug for TrustedGroup

impl Debug for TrustedUser

impl Debug for safelog::err::Error

impl Debug for ChanProvenance

impl Debug for ChannelUsage

impl Debug for Dormancy

impl Debug for tor_chanmgr::err::Error

impl Debug for ConnBlockage

impl Debug for tor_chanmgr::transport::proxied::Protocol

impl Debug for ProxyError

impl Debug for tor_circmgr::err::Error

impl Debug for StreamIsolationBuilderError

impl Debug for tor_circmgr::timeouts::Action

impl Debug for AnonymizedRequest

impl Debug for RequestError

impl Debug for tor_geoip::err::Error

impl Debug for BridgeParseError

impl Debug for BridgeDescEvent

impl Debug for ExternalActivity

impl Debug for GuardRestriction

impl Debug for GuardUsageKind

impl Debug for RetireCircuits

impl Debug for VanguardMode

impl Debug for GuardMgrConfigError

impl Debug for GuardMgrError

impl Debug for PickGuardError

impl Debug for GuardStatus

impl Debug for Layer

impl Debug for VanguardMgrError

impl Debug for ArtiPathSyntaxError

impl Debug for tor_keymgr::err::Error

impl Debug for KeystoreCorruptionError

impl Debug for RawComponentParseResult

impl Debug for ArtiPathUnavailableError

impl Debug for InvalidKeyPathComponentValue

impl Debug for KeyPathError

impl Debug for KeyPathPattern

impl Debug for tor_keymgr::key_type::KeyType

impl Debug for KeyMgrBuilderError

impl Debug for SshKeyAlgorithm

impl Debug for ChanTargetDecodeError

impl Debug for Strictness

impl Debug for RelayId

impl Debug for RelayIdError

impl Debug for RelayIdType

impl Debug for LinkSpec

impl Debug for BridgeAddrError

impl Debug for ChannelMethod

impl Debug for PtTargetAddr

impl Debug for PtTargetInvalidSetting

impl Debug for TransportIdError

impl Debug for InstallRuntimeError

impl Debug for DirEvent

impl Debug for HsDirOp

impl Debug for RelayLookupError

impl Debug for tor_netdir::err::Error

impl Debug for OnionDirLookupError

impl Debug for WeightRole

impl Debug for LockStatus

impl Debug for ErrorSource

impl Debug for BadSlug

impl Debug for Liveness

impl Debug for tor_protover::ParseError

impl Debug for SleepError

impl Debug for tor_socksproto::err::Error

impl Debug for SocksAddr

impl Debug for SocksAuth

impl Debug for SocksVersion

impl Debug for tor_units::Error

impl Debug for Anonymity

impl Debug for AuthorizedClientConfig

Trait tor_hsservice::internal_prelude::Debug