flams_router_vscode::server_fn::inventory::core::fmt

Trait Debug

1.6.0 · Source

pub 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 };

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

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 DebugCopy item path

§Stability

§Examples

Required Methods§

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

§Errors

§Examples

Trait Implementations§

impl<'v, 'u> From<&'v &'u dyn Debug> for ValueBag<'v>where 'u: 'v,

fn from(v: &'v &'u dyn Debug) -> ValueBag<'v>

impl<'v> From<&'v dyn Debug> for ValueBag<'v>

fn from(v: &'v dyn Debug) -> ValueBag<'v>

Implementors§

impl Debug for UserError

impl Debug for LoginError

impl Debug for OAuthError

impl Debug for flams_git::gl::Err

impl Debug for ArchiveDatum

impl Debug for ArchiveIndex

impl Debug for DocumentKind

impl Debug for Institution

impl Debug for flams_ontology::content::declarations::symbols::AssocType

impl Debug for ModuleLike

impl Debug for ArgMode

impl Debug for Informal

impl Debug for flams_ontology::content::terms::Term

impl Debug for flams_ontology::content::terms::Var

impl Debug for SlideElement

impl Debug for FTMLKey

impl Debug for flams_ontology::languages::Language

impl Debug for LOKind

impl Debug for NotationComponent

impl Debug for PresentationError

impl Debug for ParagraphFormatting

impl Debug for ParagraphKind

impl Debug for AnswerKind

impl Debug for CheckedResult

impl Debug for CognitiveDimension

impl Debug for FillInSolOption

impl Debug for FillinFeedbackKind

impl Debug for ProblemResponseType

impl Debug for QuizElement

impl Debug for SolutionData

impl Debug for SectionLevel

impl Debug for SearchIndex

impl Debug for SearchResult

impl Debug for SearchResultKind

impl Debug for ContentURI

impl Debug for ContentURIRef<'_>

impl Debug for URI

impl Debug for URIRef<'_>

impl Debug for URIParseError

impl Debug for NarrativeURI

impl Debug for NarrativeURIRef<'_>

impl Debug for TermURI

impl Debug for TermURIRef<'_>

impl Debug for LoginState

impl Debug for flams_system::backend::archives::Archive

impl Debug for ArchiveOrGroup

impl Debug for FileState

impl Debug for SourceEntry

impl Debug for AnyBackend

impl Debug for BackendChange

impl Debug for SandboxedRepository

impl Debug for flams_system::building::Dependency

impl Debug for QueueMessage

impl Debug for TaskState

impl Debug for QueueName

impl Debug for CSS

impl Debug for CowStr

impl Debug for LogFileLine

impl Debug for LogLevel

impl Debug for LogTreeElem

impl Debug for ThemeType

impl Debug for FromToBytesCodecError

impl Debug for Env

impl Debug for FromFormDataError

impl Debug for flams_router_vscode::FromUtf8Error

impl Debug for ReloadWSProtocol

impl Debug for ServerFnErrorErr

Trait Debug

impl<'v, 'u> From<&'v &'u dyn Debug> for ValueBag<'v>
where 'u: 'v,