::ext-trait

Annotation to easily define ad-hoc / one-shot extension traits.

Examples

• Also

  ```rust ,no_run

  [macro_use]

  extern crate ext_trait;

  [extension(trait Also)]

  impl 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());
  

  } ```

• WithPath

  ```rust ,no_run

  [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) -> PathBuf { self.push(segment); self } }

  fn main () -> Result<(), Box> { let somedir = PathBuf::from(::std::env::var("MYLIBSOMEDIR")?); // No unnecessary clones! let somesubdir = somedir.with("some").with("sub").with("dir"); // … Ok(()) } ```

• Context

  ```rust ,no_run

  [macro_use]

  extern crate ext_trait;

  use ::std::{error::Error, fmt::Display};

  [extension(trait Context)]

  impl Result { fn context (self, prefix: impl Display) -> Result { self.map_err(|err| format!("{}: {}", prefix, err)) } }

  fn main () -> Result<(), Box> { let filecontents = ::std::fs::readto_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!