examples

Author: PeterIvanov

error.go

@@ -142,7 +142,12 @@ func (e *Error) Cause() error {
 }
 
 // Format implements the Formatter interface.
-// Supports %v or %s for simple message output, and %+v for full output complete with a stack trace.
+// Supported verbs:
+//
+// 		%s		simple message output
+// 		%v 		same as %s
+// 		%+v 	full output complete with a stack trace
+//
 // In is nearly always preferable to use %+v format.
 // If a stack trace is not required, it should be omitted at the moment of creation rather in formatting.
 func (e *Error) Format(s fmt.State, verb rune) {

example_test.go

@@ -62,6 +62,182 @@ func ExampleType_Wrap() {
 	// common.assertion_failed: wrapped, cause: common.illegal_argument
 }
 
+func ExampleError_Format() {
+	err := nestedCall()
+
+	simpleOutput := fmt.Sprintf("Error short: %v\n", err)
+	verboseOutput := fmt.Sprintf("Error full: %+v", err)
+
+	fmt.Println(simpleOutput)
+	fmt.Println(verboseOutput)
+
+	// Example output:
+	//Error short: common.assertion_failed: example
+	//
+	//Error full: common.assertion_failed: example
+	// at github.com/joomcode/errorx_test.someFunc()
+	//	/Users/p.ivanov/go/src/github.com/joomcode/errorx/example_test.go:102
+	// at github.com/joomcode/errorx_test.nestedCall()
+	//	/Users/p.ivanov/go/src/github.com/joomcode/errorx/example_test.go:98
+	// at github.com/joomcode/errorx_test.ExampleError_Format()
+	//	/Users/p.ivanov/go/src/github.com/joomcode/errorx/example_test.go:66
+	// <...> more
+}
+
+func ExampleEnhanceStackTrace() {
+	errCh := make(chan error)
+	go func() {
+		errCh <- nestedCall()
+	}()
+
+	err := <- errCh
+	verboseOutput := fmt.Sprintf("Error full: %+v", errorx.EnhanceStackTrace(err, "another goroutine"))
+	fmt.Println(verboseOutput)
+
+	// Example output:
+	//Error full: another goroutine, cause: common.assertion_failed: example
+	// at github.com/joomcode/errorx_test.ExampleEnhanceStackTrace()
+	//	/Users/p.ivanov/go/src/github.com/joomcode/errorx/example_test.go:94
+	// at testing.runExample()
+	//	/usr/local/Cellar/go/1.10.3/libexec/src/testing/example.go:122
+	// at testing.runExamples()
+	//	/usr/local/Cellar/go/1.10.3/libexec/src/testing/example.go:46
+	// at testing.(*M).Run()
+	//	/usr/local/Cellar/go/1.10.3/libexec/src/testing/testing.go:979
+	// at main.main()
+	//	_testmain.go:146
+	// ...
+	// (1 duplicated frames)
+	// ----------------------------------
+	// at github.com/joomcode/errorx_test.someFunc()
+	//	/Users/p.ivanov/go/src/github.com/joomcode/errorx/example_test.go:106
+	// at github.com/joomcode/errorx_test.nestedCall()
+	//	/Users/p.ivanov/go/src/github.com/joomcode/errorx/example_test.go:102
+	// at github.com/joomcode/errorx_test.ExampleEnhanceStackTrace.func1()
+	//	/Users/p.ivanov/go/src/github.com/joomcode/errorx/example_test.go:90
+	// at runtime.goexit()
+	//	/usr/local/Cellar/go/1.10.3/libexec/src/runtime/asm_amd64.s:2361
+}
+
+func ExampleIgnore() {
+	err := errorx.IllegalArgument.NewWithNoMessage()
+	err = errorx.Decorate(err, "more info")
+
+	fmt.Println(err)
+	fmt.Println(errorx.Ignore(err, errorx.IllegalArgument))
+	fmt.Println(errorx.Ignore(err, errorx.AssertionFailed))
+
+	// Output:
+	// more info, cause: common.illegal_argument
+	// <nil>
+	// more info, cause: common.illegal_argument
+}
+
+func ExampleIgnoreWithTrait() {
+	err := errorx.TimeoutElapsed.NewWithNoMessage()
+	err = errorx.Decorate(err, "more info")
+
+	fmt.Println(err)
+	fmt.Println(errorx.IgnoreWithTrait(err, errorx.Timeout()))
+	fmt.Println(errorx.IgnoreWithTrait(err, errorx.NotFound()))
+
+	// Output:
+	// more info, cause: common.timeout
+	// <nil>
+	// more info, cause: common.timeout
+}
+
+func ExampleIsOfType() {
+	err0 := errorx.DataUnavailable.NewWithNoMessage()
+	err1 := errorx.Decorate(err0, "decorated")
+	err2 := errorx.RejectedOperation.Wrap(err0, "wrapped")
+
+	fmt.Println(errorx.IsOfType(err0, errorx.DataUnavailable))
+	fmt.Println(errorx.IsOfType(err1, errorx.DataUnavailable))
+	fmt.Println(errorx.IsOfType(err2, errorx.DataUnavailable))
+
+	// Output:
+	// true
+	// true
+	// false
+}
+
+func ExampleTypeSwitch() {
+	err := errorx.DataUnavailable.NewWithNoMessage()
+
+	switch errorx.TypeSwitch(err, errorx.DataUnavailable) {
+	case errorx.DataUnavailable:
+		fmt.Println("good")
+	case nil:
+		fmt.Println("bad")
+	default:
+		fmt.Println("bad")
+	}
+
+	switch errorx.TypeSwitch(nil, errorx.DataUnavailable) {
+	case errorx.DataUnavailable:
+		fmt.Println("bad")
+	case nil:
+		fmt.Println("good")
+	default:
+		fmt.Println("bad")
+	}
+
+	switch errorx.TypeSwitch(err, errorx.TimeoutElapsed) {
+	case errorx.TimeoutElapsed:
+		fmt.Println("bad")
+	case nil:
+		fmt.Println("bad")
+	default:
+		fmt.Println("good")
+	}
+
+	// Output:
+	// good
+	// good
+	// good
+}
+
+func ExampleTraitSwitch() {
+	err := errorx.TimeoutElapsed.NewWithNoMessage()
+
+	switch errorx.TraitSwitch(err, errorx.Timeout()) {
+	case errorx.Timeout():
+		fmt.Println("good")
+	case errorx.CaseNoError():
+		fmt.Println("bad")
+	default:
+		fmt.Println("bad")
+	}
+
+	switch errorx.TraitSwitch(nil, errorx.Timeout()) {
+	case errorx.Timeout():
+		fmt.Println("bad")
+	case errorx.CaseNoError():
+		fmt.Println("good")
+	default:
+		fmt.Println("bad")
+	}
+
+	switch errorx.TraitSwitch(err, errorx.NotFound()) {
+	case errorx.NotFound():
+		fmt.Println("bad")
+	case errorx.CaseNoError():
+		fmt.Println("bad")
+	default:
+		fmt.Println("good")
+	}
+
+	// Output:
+	// good
+	// good
+	// good
+}
+
+func nestedCall() error {
+	return someFunc()
+}
+
 func someFunc() error {
 	return errorx.AssertionFailed.New("example")
 }