Move benchmark assigned err to global exported variable (#106)

toperr is not used, but the go compiler itself doesn't detect this
because it's within an anonymous function. However, go/types does
detect this as being unused, which causes any static analysis tools
which uses go/types' type checker to fail with the message "toperr
assigned and not used".

The final result of the benchmarked function is instead assigned to
an exported global variable to ensure the compiler cannot now, nor
in the future optimise away the function calls due to no observable
side effects.

It was chosen to assign the final result, after the benchmark loop,
to the global variable, as this best follows the example set in the
CL As opposed to
having each call to f assign to the global. This also appears to
better align with the original author's intention of toperr.

This change had no observable impact on the benchmark.


Thanks dominikh for additional clarifications.
1 file changed
tree: 1d136848862d24a94aa103ecbd726c468bf56d1b
  1. .gitignore
  2. .travis.yml
  5. appveyor.yml
  6. bench_test.go
  7. errors.go
  8. errors_test.go
  9. example_test.go
  10. format_test.go
  11. stack.go
  12. stack_test.go

errors Travis-CI AppVeyor GoDoc Report card

Package errors provides simple error handling primitives.

go get

The traditional error handling idiom in Go is roughly akin to

if err != nil {
        return err

which applied recursively up the call stack results in error reports without context or debugging information. The errors package allows programmers to add context to the failure path in their code in a way that does not destroy the original value of the error.

Adding context to an error

The errors.Wrap function returns a new error that adds context to the original error. For example

_, err := ioutil.ReadAll(r)
if err != nil {
        return errors.Wrap(err, "read failed")

Retrieving the cause of an error

Using errors.Wrap constructs a stack of errors, adding context to the preceding error. Depending on the nature of the error it may be necessary to reverse the operation of errors.Wrap to retrieve the original error for inspection. Any error value which implements this interface can be inspected by errors.Cause.

type causer interface {
        Cause() error

errors.Cause will recursively retrieve the topmost error which does not implement causer, which is assumed to be the original cause. For example:

switch err := errors.Cause(err).(type) {
case *MyError:
        // handle specifically
        // unknown error

Read the package documentation for more information.


We welcome pull requests, bug fixes and issue reports. With that said, the bar for adding new symbols to this package is intentionally set high.

Before proposing a change, please discuss your change by raising an issue.