6 releases (3 stable)
2.0.0 | Jul 11, 2024 |
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2.0.0-rc1 | Jul 10, 2024 |
1.0.1 | Jan 18, 2022 |
1.0.0 | Oct 23, 2021 |
0.1.0-rc2 | Oct 23, 2021 |
#380 in Rust patterns
119,005 downloads per month
Used in 63 crates
(3 directly)
11KB
59 lines
::ext-trait
Annotation to easily define ad-hoc / one-shot extension traits.
Examples
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Also
#[macro_use] extern crate ext_trait; #[extension(trait Also)] impl<T> T { fn also (mut self, f: impl FnOnce(&mut Self)) -> Self { f(&mut self); self } } fn main () { use ::std::{collections::HashMap, ops::Not}; let /* immut */ map = HashMap::with_capacity(2).also(|m| { m.insert("foo", 42); m.insert("bar", 27); }); assert!(map.contains_key("foo")); assert!(map.contains_key("bar")); assert!(map.contains_key("baz").not()); }
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WithPath
#[macro_use] extern crate ext_trait; use ::std::{error::Error, path::{Path, PathBuf}}; #[extension(trait WithPath)] impl PathBuf { fn with (mut self, segment: impl AsRef<Path>) -> PathBuf { self.push(segment); self } } fn main () -> Result<(), Box<dyn Error>> { let some_dir = PathBuf::from(::std::env::var("MY_LIB_SOME_DIR")?); // Contrary to chaining `.join()`, this reuses the memory! let some_subdir = some_dir.with("some").with("sub").with("dir"); // … Ok(()) }
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Context
#[macro_use] extern crate ext_trait; use ::std::{error::Error, fmt::Display}; #[extension(trait Context)] impl<Ok, Err : Display> Result<Ok, Err> { fn context (self, prefix: impl Display) -> Result<Ok, String> { self.map_err(|err| format!("{}: {}", prefix, err)) } } fn main () -> Result<(), Box<dyn Error>> { let file_contents = ::std::fs::read_to_string("some/file") .context("Error when opening some/file")? ; // … Ok(()) }
Similar to https://docs.rs/extension-trait, but for the following:
Features
-
Supports generics (see
Context
) -
search/
grep 'trait TraitName'
-friendly!
Dependencies
~1.5MB
~37K SLoC