From 37acf646f4b06eacbafc7e4c72943d1afd1788cb Mon Sep 17 00:00:00 2001
From: Timon Ringwald <timon.ringwald@m2xpert.com>
Date: Wed, 9 Sep 2020 14:06:31 +0200
Subject: [PATCH] README.md improved

---
 README.md     | 75 ++++++++++++++++++++++++++++++++++++++++++++++++++-
 calltrace.go  | 13 ++++++---
 error.go      |  2 +-
 error_tmpl.go | 10 +++++++
 globals.go    |  8 +++---
 5 files changed, 99 insertions(+), 9 deletions(-)

diff --git a/README.md b/README.md
index 4f28c38..99a8908 100644
--- a/README.md
+++ b/README.md
@@ -83,4 +83,77 @@ func doStuffWrapped() error {
 fmt.Println(adverr.Trace())
 ```
 
-### 
\ No newline at end of file
+### Example of a printed error
+Code:
+```go
+package main
+
+import (
+	"adverr"
+	"errors"
+)
+
+var (
+	ErrDoStuffFailed = adverr.NewErrTmpl("ErrDoStuffFailed", "Could'nt do stuff because of %s")
+)
+
+func main() {
+	err := doStuffInAnotherGoroutine()
+	if err != nil {
+		adverr.Fatalln(err, 1)
+	}
+}
+
+func doStuff() error {
+	err := doGoNativeStuff()
+	if err != nil {
+		return ErrDoStuffFailed.Wrap(err, "reasons")
+	}
+
+	return nil
+}
+
+func doStuffInAnotherGoroutine() error {
+	ch := make(chan error, 1)
+
+	go func() {
+		ch <- doStuff()
+		close(ch)
+	}()
+
+	err := <-ch
+	if err != nil {
+		return adverr.Wrap("Goroutine failed because of errors", err)
+	}
+
+	return nil
+}
+
+func doGoNativeStuff() error {
+	return errors.New("some go error")
+}
+
+```
+Output:
+```
+adverr.Error: Goroutine failed because of errors
+        at main.doStuffInAnotherGoroutine (/home/user/go/src/test/main.go:38)
+        at main.main (/home/user/go/src/test/main.go:13)
+        at runtime.main (/usr/local/go/src/runtime/proc.go:204)
+Caused by ErrDoStuffFailed: Could'nt do stuff because of reasons
+        at main.doStuff (/home/user/go/src/test/main.go:22)
+        at main.doStuffInAnotherGoroutine.func1 (/home/user/go/src/test/main.go:32)
+Caused by errors.errorString: some go error
+        (Unknown source)
+```
+
+### Globals
+You can set the maximum limit of the call stack trace via
+```go
+adverr.CallStackLength = 50 // default value: 100
+```
+
+If you are in a productive environment, consider disabling call traces completely for performance reasons:
+```go
+adverr.DisableTrace = true // default value: false
+```
\ No newline at end of file
diff --git a/calltrace.go b/calltrace.go
index 4a99722..3368131 100644
--- a/calltrace.go
+++ b/calltrace.go
@@ -1,6 +1,7 @@
 package adverr
 
 import (
+	"fmt"
 	"runtime"
 	"strconv"
 	"strings"
@@ -9,19 +10,21 @@ import (
 // CallTrace represents a call stack trace similar to Java's stack trace
 type CallTrace struct {
 	frames *runtime.Frames
+	more   bool
 }
 
 // Trace returns a new CallTrace starting from this call
 // Use skip to skip the first entries in the trace
 func Trace(skip int) *CallTrace {
-	if !TraceCallStack {
+	if DisableTrace {
 		return nil
 	}
 
-	pc := make([]uintptr, CallStackLength)
+	pc := make([]uintptr, CallStackLength+1)
 	n := runtime.Callers(skip+1, pc)
 	pc = pc[:n]
-	return &CallTrace{runtime.CallersFrames(pc)}
+	fmt.Println(n, CallStackLength)
+	return &CallTrace{runtime.CallersFrames(pc), n == CallStackLength+1}
 }
 
 func (ct *CallTrace) String() string {
@@ -42,5 +45,9 @@ func (ct *CallTrace) String() string {
 		b.WriteString("\n")
 	}
 
+	if ct.more {
+		b.WriteString("\t ...\n")
+	}
+
 	return b.String()
 }
diff --git a/error.go b/error.go
index e4f49e3..749d6df 100644
--- a/error.go
+++ b/error.go
@@ -89,7 +89,7 @@ func printErr(err error, b *strings.Builder) {
 		b.WriteString(errtype(err))
 		b.WriteString(": ")
 		b.WriteString(err.Error())
-		b.WriteString("\n")
+		b.WriteString("\n\t(Unknown source)\n")
 	}
 
 	cause := errors.Unwrap(err)
diff --git a/error_tmpl.go b/error_tmpl.go
index 11e088c..16e6e29 100644
--- a/error_tmpl.go
+++ b/error_tmpl.go
@@ -33,3 +33,13 @@ func (t *ErrTmpl) New(args ...interface{}) *Error {
 		callTrace: Trace(2),
 	}
 }
+
+// Wrap returns a new Error with a given cause in which args are being formatted into the format string of its template
+func (t *ErrTmpl) Wrap(cause error, args ...interface{}) *Error {
+	return &Error{
+		msg:       fmt.Sprintf(t.format, args...),
+		cause:     cause,
+		tmpl:      t,
+		callTrace: Trace(2),
+	}
+}
diff --git a/globals.go b/globals.go
index 4c6de23..dff85da 100644
--- a/globals.go
+++ b/globals.go
@@ -1,9 +1,9 @@
 package adverr
 
-// TraceCallStack decides if any call stack traces will be gathered when creating Errors
-// If your application is doing performance-heavy tasks with lots of Error creations, you may consider setting this to false
-// If set to false, all CallTraces in Error will be nil
-var TraceCallStack bool = true
+// DisableTrace decides if any call stack traces will be gathered when creating Errors
+// If your application is doing performance-heavy tasks with lots of Error creations, you may consider setting this to true
+// If set to true, all CallTraces in Error will be nil
+var DisableTrace bool = true
 
 // CallStackLength decides how many calls from the call stack should be gathered at most
 var CallStackLength int = 100