Struct Output

pub struct Output(/* private fields */);

Represents an output sink, which can be either standard output or a file.

Examples

use std::io::{self, Write as _};

use clap::Parser as _;
use clap_file::Output;

#[derive(Debug, clap::Parser)]
struct Args {
    /// output file. If not provided, reads from standard output.
    output: Output,
}

fn main() -> io::Result<()> {
    let args = Args::parse();
    let mut output = args.output.lock();
    writeln!(&mut output, "Hello, world!")?;
    Ok(())
}

Implementations

impl Output

pub fn stdout() -> Self

Creates a new Output instance that writes to standard output.

pub fn create(path: PathBuf) -> Result<Self>

Creates a file at the given path and creates a new Output instance that writes to it.

pub fn is_stdout(&self) -> bool

Returns true if this Output writes to standard output.

pub fn is_file(&self) -> bool

Returns true if this Output writes to a file.

pub fn path(&self) -> Option<&Path>

Returns the path of the file this Output writes to.

Returns None if this Output writes to standard output.

pub fn lock(&self) -> LockedOutput<'_>

Locks this Output for writing and returns a writable guard.

This lock is released when the returned LockedOutput instance is dropped. The returned LockedOutput instance implements Write trait for writing data.

Trait Implementations

impl Clone for Output

fn clone(&self) -> Output

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Debug for Output

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

Formats the value using the given formatter.

impl FromStr for Output

type Err = Error

The associated error which can be returned from parsing.

fn from_str(s: &str) -> Result<Self, Self::Err>

Parses a string s to return a value of this type.

impl Write for Output

fn write(&mut self, buf: &[u8]) -> Result<usize>

Writes a buffer into this writer, returning how many bytes were written.

fn flush(&mut self) -> Result<()>

Flushes this output stream, ensuring that all intermediately buffered contents reach their destination.

fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> Result<usize>

Like write, except that it writes from a slice of buffers.

fn write_all(&mut self, buf: &[u8]) -> Result<()>

Attempts to write an entire buffer into this writer.

fn is_write_vectored(&self) -> bool

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

Determines if this Writer has an efficient write_vectored implementation.

fn write_all_vectored(&mut self, bufs: &mut [IoSlice<'_>]) -> Result<(), Error>

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

Attempts to write multiple buffers into this writer.

fn write_fmt(&mut self, args: Arguments<'_>) -> Result<(), Error>

Writes a formatted string into this writer, returning any error encountered.

fn by_ref(&mut self) -> &mut Self

where Self: Sized,

Creates a “by reference” adapter for this instance of Write.