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.

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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>>

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Implementors

impl<I> Size for Slice<I>

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

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