▾ Example

Code:

package errors_test

import (
    "fmt"
    "time"
)

// MyError is an error implementation that includes a time and message.
type MyError struct {
    When time.Time
    What string
}

func (e MyError) Error() string {
    return fmt.Sprintf("%v: %v", e.When, e.What)
}

func oops() error {
    return MyError{
        time.Date(1989, 3, 15, 22, 30, 0, 0, time.UTC),
        "the file system has gone away",
    }
}

func Example() {
    if err := oops(); err != nil {
        fmt.Println(err)
    }
    // Output: 1989-03-15 22:30:00 +0000 UTC: the file system has gone away
}

Internal call graph ▾

In the call graph viewer below, each node is a function belonging to this package and its children are the functions it calls—perhaps dynamically.

The root nodes are the entry points of the package: functions that may be called from outside the package. There may be non-exported or anonymous functions among them if they are called dynamically from another package.

Click a node to visit that function's source code. From there you can visit its callers by clicking its declaring func token.

Functions may be omitted if they were determined to be unreachable in the particular programs or tests that were analyzed.

▾ Example

Code:

err := errors.New("emit macho dwarf: elf header corrupted")
if err != nil {
    fmt.Print(err)
}

Output:

emit macho dwarf: elf header corrupted

▾ Example (Errorf)

The fmt package's Errorf function lets us use the package's formatting features to create descriptive error messages.

Code:

const name, id = "bimmler", 17
err := fmt.Errorf("user %q (id %d) not found", name, id)
if err != nil {
    fmt.Print(err)
}

Output:

user "bimmler" (id 17) not found