commit 127882ebf0b752d3c99fec3613c4487b193412e8
author Abhinav Gupta <abg@uber.com> Thu Sep 26 13:24:24 2019 -0700
committer GitHub <noreply@github.com> Thu Sep 26 13:24:24 2019 -0700
tree b67cfb089b177b1fbb7ab1d5e650b09e9668b348
parent bd075f90b08f5274a0bc63bcffacd6c64b60ac55

Support errors.As and errors.Is (#28)

Go 1.13 includes the `errors.As` and `errors.Is` APIs.

The base functionality provided by these functions is to cast errors in
an error chain to a specific type or check for equality.

The only definition of error chain currently supported is via errors
which return the underlying cause with a `Unwrap() error` method, but
the design does not make any assumptions otherwise.

Specifically, both, `errors.As` and `errors.Is` support customizing
their behavior by implementing,

    interface { As(interface{}) bool }
    interface { Is(error) bool }

This change does exactly that, making it possible to extract or match
against individual errors in a multierr error. This will work for both,
top-level errors in a multierr error, as well as for errors wrapped by
any of those errors.