Struct deterministic::file::OpenOptions
source · pub struct OpenOptions { /* private fields */ }
Expand description
Options and flags which can be used to configure how a file is opened.
This builder exposes the ability to configure how a File
is opened and
what operations are permitted on the open file. The File::open
and
File::create
methods are aliases for commonly used options using this
builder.
Generally speaking, when using OpenOptions
, you’ll first call new
,
then chain calls to methods to set each option, then call open
,
passing the path of the file you’re trying to open. This will give you a
io::Result
with a File
inside that you can further
operate on.
Examples
Opening a file to read:
use std::fs::OpenOptions;
let file = OpenOptions::new().read(true).open("foo.txt");
Opening a file for both reading and writing, as well as creating it if it doesn’t exist:
use std::fs::OpenOptions;
let file = OpenOptions::new()
.read(true)
.write(true)
.create(true)
.open("foo.txt");
Implementations
sourceimpl OpenOptions
impl OpenOptions
sourcepub fn new() -> OpenOptions
pub fn new() -> OpenOptions
Creates a blank new set of options ready for configuration.
All options are initially set to false
.
Examples
use std::fs::OpenOptions;
let mut options = OpenOptions::new();
let file = options.read(true).open("foo.txt");
sourcepub fn read(&mut self, read: bool) -> &mut OpenOptions
pub fn read(&mut self, read: bool) -> &mut OpenOptions
Sets the option for read access.
This option, when true, will indicate that the file should be
read
-able if opened.
Examples
use std::fs::OpenOptions;
let file = OpenOptions::new().read(true).open("foo.txt");
sourcepub fn write(&mut self, write: bool) -> &mut OpenOptions
pub fn write(&mut self, write: bool) -> &mut OpenOptions
Sets the option for write access.
This option, when true, will indicate that the file should be
write
-able if opened.
If the file already exists, any write calls on it will overwrite its contents, without truncating it.
Examples
use std::fs::OpenOptions;
let file = OpenOptions::new().write(true).open("foo.txt");
sourcepub fn create(&mut self, create: bool) -> &mut OpenOptions
pub fn create(&mut self, create: bool) -> &mut OpenOptions
Sets the option for creating a new file.
This option indicates whether a new file will be created if the file does not yet already exist.
In order for the file to be created, write
or append
access must
be used.
Examples
use std::fs::OpenOptions;
let file = OpenOptions::new().write(true).create(true).open("foo.txt");
sourcepub fn truncate(&mut self, truncate: bool) -> &mut OpenOptions
pub fn truncate(&mut self, truncate: bool) -> &mut OpenOptions
Sets the option for truncating a previous file.
If a file is successfully opened with this option set it will truncate the file to 0 length if it already exists.
The file must be opened with write access for truncate to work.
Examples
use std::fs::OpenOptions;
let file = OpenOptions::new().write(true).truncate(true).open("foo.txt");
sourcepub fn open<P: AsRef<Path>>(&self, path: P) -> Result<File>
pub fn open<P: AsRef<Path>>(&self, path: P) -> Result<File>
Opens a file at path
with the options specified by self
.
Errors
This function will return an error under a number of different
circumstances. Some of these error conditions are listed here, together
with their ErrorKind
. The mapping to ErrorKind
s is not part of
the compatibility contract of the function, especially the Other
kind
might change to more specific kinds in the future.
- [
NotFound
]: The specified file does not exist and neithercreate
orcreate_new
is set. - [
NotFound
]: One of the directory components of the file path does not exist. - [
PermissionDenied
]: The user lacks permission to get the specified access rights for the file. - [
PermissionDenied
]: The user lacks permission to open one of the directory components of the specified path. - [
AlreadyExists
]:create_new
was specified and the file already exists. - [
InvalidInput
]: Invalid combinations of open options (truncate without write access, no access mode set, etc.). - [
Other
]: One of the directory components of the specified file path was not, in fact, a directory. - [
Other
]: Filesystem-level errors: full disk, write permission requested on a read-only file system, exceeded disk quota, too many open files, too long filename, too many symbolic links in the specified path (Unix-like systems only), etc.
Examples
use std::fs::OpenOptions;
let file = OpenOptions::new().open("foo.txt");
Trait Implementations
sourceimpl Clone for OpenOptions
impl Clone for OpenOptions
sourcefn clone(&self) -> OpenOptions
fn clone(&self) -> OpenOptions
1.0.0 · sourcefn clone_from(&mut self, source: &Self)
fn clone_from(&mut self, source: &Self)
source
. Read more