Trait positioned_io_preview::Size

pub trait Size {
    fn size(&self) -> Result<Option<u64>>;
}

Trait to get the size in bytes of an I/O object.

Implementing this for a types with ReadAt or WriteAt makes it easier for users to predict whether they will read past end-of-file. However, it may not be possible to implement for certain readers or writers that have unknown size.

Examples

use std::fs::File;
use positioned_io::Size;

let file = File::open("tests/pi.txt")?;
let size = file.size()?;
assert_eq!(size, Some(1000002));

// some special files do not have a known size
let file = File::open("/dev/stdin")?;
let size = file.size()?;
assert_eq!(size, None);

Required Methods

fn size(&self) -> Result<Option<u64>>

Get the size of this object, in bytes.

This function may return Ok(None) if the size is unknown, for example for pipes.

Implementations on Foreign Types

impl Size for File

fn size(&self) -> Result<Option<u64>>

impl<'a> Size for &'a [u8]

fn size(&self) -> Result<Option<u64>>

impl<'a> Size for &'a mut [u8]

fn size(&self) -> Result<Option<u64>>

impl Size for Vec<u8>

fn size(&self) -> Result<Option<u64>>

impl<'a, S: Size + ?Sized> Size for &'a S

fn size(&self) -> Result<Option<u64>>

impl<'a, S: Size + ?Sized> Size for &'a mut S

fn size(&self) -> Result<Option<u64>>

impl<'a, S: Size> Size for &'a RefCell<S>

fn size(&self) -> Result<Option<u64>>

Implementors

impl<I> Size for Slice<I>