Crate io_providers [−] [src]
Defines "provider" traits and implementations for different types of I/O operations.
The purpose of this is mainly for dependency injection: by having your code depend on a generic provider, it can be tested by giving it a virtual, inspectable implementation of that provider. In production, the "real" implementation can be used.
Each type of provider exists in its own submodule and can be used independently. However,
this module also contains the all-encompassing IoProvider
trait which provides access to
all of them. If you have a lot of I/O dependencies, it might be easier to create and pass
around one &mut IoProvider
rather than several different providers.
Examples
extern crate io_providers; use std::io::Write; use std::path::Path; use io_providers::{IoProvider, LocalIoProvider, VirtualIoProvider}; use io_providers::env::Provider as EnvProvider; use io_providers::stream::Provider as StreamProvider; /// Gets the current working directory and prints it to stdout. fn do_work<P: IoProvider>(io: &mut P) { let cur_dir = io.env().current_dir().unwrap(); let stdout = io.stream().output(); writeln!(stdout, "The current directory is: {}", cur_dir.to_str().unwrap()).unwrap(); } fn main() { test_do_work_prints_current_dir(); // Use a local I/O provider here to get real interaction with the system let mut io = LocalIoProvider::new(); do_work(&mut io); } fn test_do_work_prints_current_dir() { // Use a virtual I/O provider here so we can verify how it was used let mut virtual_io = VirtualIoProvider::new(); virtual_io.env().set_current_dir(Path::new("/foo/bar")).unwrap(); do_work(&mut virtual_io); assert_eq!( "The current directory is: /foo/bar\n", ::std::str::from_utf8(virtual_io.stream().read_output()).unwrap()); }
Modules
env |
Providers of environment data, such as the working directory and environment variables. |
stream |
Providers of input/output/error streams (i.e. stdin, stdout and stderr). |
Structs
LocalIoProvider |
"Real" implementer of |
VirtualIoProvider |
Virtual implementer of |
Traits
IoProvider |
Provides access to an environment provider and a stream provider. |