1.0.29

• Documentation improvements

1.0.28

• Documentation improvements (#73, #78)

1.0.27

• Improve documentation of backtrace environment variable combinations (#69)

  • If you want panics and errors to both have backtraces, set RUST_BACKTRACE=1;
  • If you want only errors to have backtraces, set RUST_LIB_BACKTRACE=1;
  • If you want only panics to have backtraces, set RUST_BACKTRACE=1 and RUST_LIB_BACKTRACE=0.

1.0.26

• Fix indentation when printing causes that have a multiline error message (#54, thanks @yaahc)

1.0.25

• Add no-std support (#53)

  In no_std mode, the same API is almost all available and works the same way. To depend on Anyhow in no_std mode, disable our default enabled "std" feature in Cargo.toml. A global allocator is required.

  [dependencies]
  anyhow = { version = "1.0", default-features = false }

  Since the ?-based error conversions would normally rely on the std::error::Error trait which is only available through std, no_std mode will require an explicit .map_err(Error::msg) when working with a non-Anyhow error type inside a function that returns Anyhow's error type.

1.0.24

• Preserve cause chain when converting from Box<dyn StdError + Send + Sync> to anyhow::Error (#50)
• Work around bug in NixOS package infrastructure (#49)

1.0.23

• Add impl AsRef<dyn std::error::Error> and impl AsRef<dyn std::error::Error + Send + Sync> for anyhow::Error
• Add Chain::new constructor

1.0.22

• Preserve cause chain when bail! or ensure! is invoked with anyhow::Error as the error argument (#46)

1.0.21

• Provide DoubleEndedIterator and ExactSizeIterator implementations for anyhow::Chain to assist in custom rendering of cause chains (#45)

  let chain = err.chain();
  if chain.len() > 1 {
      eprint!("[[root cause]] ");
  }
  for err in chain.rev() {
      eprintln!("{}", err);
  }

1.0.20

• Introduce some {:#} and {:#?} alt formatting representations (#42)

  When you print an error object using "{}" or to_string(), only the outermost underlying error or context is printed, not any of the lower level causes. This is exactly as if you had called the Display impl of the error from which you constructed your anyhow::Error.

  Failed to read instrs from ./path/to/instrs.json

  To print causes as well using anyhow's default formatting of causes, use the alternate selector "{:#}".

  Failed to read instrs from ./path/to/instrs.json: No such file or directory (os error 2)

  The Debug format "{:?}" includes your backtrace if one was captured. Note that this is the representation you get by default if you return an error from fn main instead of printing it explicitly yourself.

  Error: Failed to read instrs from ./path/to/instrs.json
  
  Caused by:
      No such file or directory (os error 2)
  
  Stack backtrace:
     0: <E as anyhow::context::ext::StdError>::ext_context
               at /git/anyhow/src/backtrace.rs:26
     1: core::result::Result<T,E>::map_err
               at /git/rustc/src/libcore/result.rs:596
     2: anyhow::context::<impl anyhow::Context<T,E> for core::result::Result<T,E>>::with_context
               at /git/anyhow/src/context.rs:58
     3: testing::main
               at src/main.rs:5
     4: std::rt::lang_start
               at /git/rustc/src/libstd/rt.rs:61
     5: main
     6: __libc_start_main
     7: _start

  To see a conventional struct-style Debug representation, use "{:#?}".

  Error {
      context: "Failed to read instrs from ./path/to/instrs.json",
      source: Os {
          code: 2,
          kind: NotFound,
          message: "No such file or directory",
      },
  }

  If none of the built-in representations are appropriate and you would prefer to render the error and its cause chain yourself, it can be done something like this:

  use anyhow::{Context, Result};
  
  fn main() {
      if let Err(err) = try_main() {
          eprintln!("ERROR: {}", err);
          err.chain().skip(1).for_each(|cause| eprintln!("because: {}", cause));
          std::process::exit(1);
      }
  }
  
  fn try_main() -> Result<()> {
      ...
  }