issues/57: add config option for how many slices/maps to display (#58)

- Fixes: #57
- Fixes: #27

CHANGELOG.md

@@ -3,6 +3,9 @@
 Most recent version is listed first.  
 
 
+# v0.0.14
+- Add config option for how many slices/maps to display: https://github.com/komuw/kama/pull/58
+
 # v0.0.13
 - Update Go version: https://github.com/komuw/kama/pull/56
 

README.md

@@ -106,6 +106,7 @@ req.Header.Set("Content-Type", "application/octet-stream")
 req.AddCookie(&http.Cookie{Name: "hello", Value: "world"})
 
 kama.Dirp(req)
+// kama.Dirp(req, kama.Config{MaxLength: 14}) // pass in an optional config value.
 ```
 that will print:
 ```bash

dump.go

@@ -141,14 +141,18 @@ func dump(val reflect.Value, hideZeroValues bool, indentLevel int) string {
 
 func dumpString(v reflect.Value) string {
 	// dumps strings
-	maxL := 100
 
 	adder := 1 // this is a custom string type.
 	if strings.HasPrefix(fmt.Sprintf("%#v", v), `"`) {
 		adder = 2 // the `+2` is important so that the final quote `"` at end of string is not cut off
 	}
 	numEntries := v.Len()
-	constraint := int(math.Min(float64(numEntries), float64(maxL))) + adder
+	if numEntries > 0 && (fmt.Sprintf("%#v", v)[0] == 34) { // 34 is the char("")
+		adder = 2
+	}
+	newLineCount := strings.Count(fmt.Sprintf("%s", v), "\n")
+
+	constraint := int(math.Min(float64(numEntries), float64(cfg.MaxLength+50))) + adder + newLineCount
 
 	s := fmt.Sprintf("%#v", v)[:constraint]
 
@@ -218,9 +222,8 @@ func dumpSlice(v reflect.Value, hideZeroValues bool, indentLevel int) string {
 	//     1. https://github.com/sanity-io/litter/pull/43
 	//     2. https://github.com/komuw/kama/pull/28
 
-	maxL := 20
 	numEntries := v.Len()
-	constraint := int(math.Min(float64(numEntries), float64(maxL)))
+	constraint := int(math.Min(float64(numEntries), float64(cfg.MaxLength)))
 	typeName := v.Type().String()
 
 	newline := "\n"
@@ -260,9 +263,8 @@ func dumpMap(v reflect.Value, hideZeroValues bool, indentLevel int) string {
 	//     1. https://github.com/sanity-io/litter/pull/43
 	//     2. https://github.com/komuw/kama/pull/28
 
-	maxL := 20
 	numEntries := v.Len()
-	constraint := int(math.Min(float64(numEntries), float64(maxL)))
+	constraint := int(math.Min(float64(numEntries), float64(cfg.MaxLength)))
 	typeName := v.Type().String()
 
 	newline := "\n"

go.mod

@@ -3,17 +3,17 @@ module github.com/komuw/kama
 go 1.21
 
 require (
-	golang.org/x/sys v0.11.0
-	golang.org/x/tools v0.12.0
+	golang.org/x/sys v0.16.0
+	golang.org/x/tools v0.17.0
 )
 
 require (
-	github.com/google/go-cmp v0.5.9 // indirect
-	golang.org/x/mod v0.12.0 // indirect
+	github.com/google/go-cmp v0.6.0 // indirect
+	golang.org/x/mod v0.14.0 // indirect
 )
 
 require (
 	github.com/pkg/errors v0.9.1 // test
 	go.akshayshah.org/attest v1.0.2 // test
-	go.uber.org/goleak v1.2.1 // test
+	go.uber.org/goleak v1.3.0 // test
 )

go.sum

@@ -1,7 +1,7 @@
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
-github.com/google/go-cmp v0.5.9 h1:O2Tfq5qg4qc4AmwVlvv0oLiVAGB7enBSJ2x2DqQFi38=
-github.com/google/go-cmp v0.5.9/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
+github.com/google/go-cmp v0.6.0 h1:ofyhxvXcZhMsU5ulbFiLKl/XBFqE1GSq7atu8tAmTRI=
+github.com/google/go-cmp v0.6.0/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
 github.com/pkg/errors v0.9.1 h1:FEBLx1zS214owpjy7qsBeixbURkuhQAwrK5UwLGTwt4=
 github.com/pkg/errors v0.9.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
@@ -10,15 +10,15 @@ github.com/stretchr/testify v1.8.0 h1:pSgiaMZlXftHpm5L7V1+rVB+AZJydKsMxsQBIJw4PK
 github.com/stretchr/testify v1.8.0/go.mod h1:yNjHg4UonilssWZ8iaSj1OCr/vHnekPRkoO+kdMU+MU=
 go.akshayshah.org/attest v1.0.2 h1:qOv9PXCG2mwnph3g0I3yZj0rLAwLyUITs8nhxP+wS44=
 go.akshayshah.org/attest v1.0.2/go.mod h1:PnWzcW5j9dkyGwTlBmUsYpPnHG0AUPrs1RQ+HrldWO0=
-go.uber.org/goleak v1.2.1 h1:NBol2c7O1ZokfZ0LEU9K6Whx/KnwvepVetCUhtKja4A=
-go.uber.org/goleak v1.2.1/go.mod h1:qlT2yGI9QafXHhZZLxlSuNsMw3FFLxBr+tBRlmO1xH4=
-golang.org/x/mod v0.12.0 h1:rmsUpXtvNzj340zd98LZ4KntptpfRHwpFOHG188oHXc=
-golang.org/x/mod v0.12.0/go.mod h1:iBbtSCu2XBx23ZKBPSOrRkjjQPZFPuis4dIYUhu/chs=
-golang.org/x/sync v0.3.0 h1:ftCYgMx6zT/asHUrPw8BLLscYtGznsLAnjq5RH9P66E=
-golang.org/x/sync v0.3.0/go.mod h1:FU7BRWz2tNW+3quACPkgCx/L+uEAv1htQ0V83Z9Rj+Y=
-golang.org/x/sys v0.11.0 h1:eG7RXZHdqOJ1i+0lgLgCpSXAp6M3LYlAo6osgSi0xOM=
-golang.org/x/sys v0.11.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
-golang.org/x/tools v0.12.0 h1:YW6HUoUmYBpwSgyaGaZq1fHjrBjX1rlpZ54T6mu2kss=
-golang.org/x/tools v0.12.0/go.mod h1:Sc0INKfu04TlqNoRA1hgpFZbhYXHPr4V5DzpSBTPqQM=
+go.uber.org/goleak v1.3.0 h1:2K3zAYmnTNqV73imy9J1T3WC+gmCePx2hEGkimedGto=
+go.uber.org/goleak v1.3.0/go.mod h1:CoHD4mav9JJNrW/WLlf7HGZPjdw8EucARQHekz1X6bE=
+golang.org/x/mod v0.14.0 h1:dGoOF9QVLYng8IHTm7BAyWqCqSheQ5pYWGhzW00YJr0=
+golang.org/x/mod v0.14.0/go.mod h1:hTbmBsO62+eylJbnUtE2MGJUyE7QWk4xUqPFrRgJ+7c=
+golang.org/x/sync v0.6.0 h1:5BMeUDZ7vkXGfEr1x9B4bRcTH4lpkTkpdh0T/J+qjbQ=
+golang.org/x/sync v0.6.0/go.mod h1:Czt+wKu1gCyEFDUtn0jG5QVvpJ6rzVqr5aXyt9drQfk=
+golang.org/x/sys v0.16.0 h1:xWw16ngr6ZMtmxDyKyIgsE93KNKz5HKmMa3b8ALHidU=
+golang.org/x/sys v0.16.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
+golang.org/x/tools v0.17.0 h1:FvmRgNOcs3kOa+T20R1uhfP9F6HgG2mfxDv1vrx1Htc=
+golang.org/x/tools v0.17.0/go.mod h1:xsh6VxdV005rRVaS6SSAf9oiAqljS7UZUacMZ8Bnsps=
 gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
 gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

kama.go

@@ -14,8 +14,20 @@ import (
 	"fmt"
 	"reflect"
 	"strings"
+	"sync"
 )
 
+var (
+	cfg     = Config{MaxLength: 14} //nolint:gochecknoglobals
+	onceCfg *sync.Once              //nolint:gochecknoglobals
+)
+
+// Config controls how printing is going to be done.
+type Config struct {
+	// MaxLength is the length of slices/maps/strings that is going to be printed.
+	MaxLength int
+}
+
 // Dirp prints (to stdout) exported information of types, variables, packages, modules, imports
 // It also pretty prints data structures.
 //
@@ -27,12 +39,27 @@ import (
 //	kama.Dirp(&http.Request{})
 //	kama.Dirp("github.com/pkg/errors")
 //	kama.Dirp(http.Request{})
-func Dirp(i interface{}) {
-	fmt.Println(Dir(i))
+//	kama.Dirp(http.Request{}, Config{999})
+func Dirp(i interface{}, c ...Config) {
+	fmt.Println(Dir(i, c...))
 }
 
 // Dir returns exported information of types, variables, packages, modules, imports
-func Dir(i interface{}) string {
+func Dir(i interface{}, c ...Config) string {
+	if len(c) > 0 {
+		onceCfg.Do(func() {
+			cfg = c[0]
+			if cfg.MaxLength < 1 {
+				cfg.MaxLength = 1
+			}
+			if cfg.MaxLength > 10_000 {
+				// the upper limit of a slice is some significant fraction of the address space of a process.
+				// https://github.com/golang/go/issues/38673#issuecomment-643885108
+				cfg.MaxLength = 10_000
+			}
+		})
+	}
+
 	iType := reflect.TypeOf(i)
 	if iType == nil {
 		res := newVari(i)

testdata/e2e_test/map_in_a_struct_is_not_compacted.txt

@@ -25,13 +25,7 @@ SNIPPET: someStructWithMap{
    int(1009): "1009", 
    int(101): "101", 
    int(1010): "1010", 
-   int(1011): "1011", 
-   int(1012): "1012", 
-   int(1013): "1013", 
-   int(1014): "1014", 
-   int(1015): "1015", 
-   int(1016): "1016", 
-   ...<9980 more redacted>..
+   ...<9986 more redacted>..
     },
 }
 ]

testdata/e2e_test/map_on_its_own_is_not_compacted.txt

@@ -22,12 +22,6 @@ SNIPPET: map[int]string{
    int(1009): "1009", 
    int(101): "101", 
    int(1010): "1010", 
-   int(1011): "1011", 
-   int(1012): "1012", 
-   int(1013): "1013", 
-   int(1014): "1014", 
-   int(1015): "1015", 
-   int(1016): "1016", 
-   ...<9980 more redacted>..
+   ...<9986 more redacted>..
   }
 ]

testdata/e2e_test/pointer_to_struct_of_varying_field_types.txt.txt

@@ -81,32 +81,14 @@ SNIPPET: &SomeStruct{
    Request{
       Method: "13",
     },
-   Request{
-      Method: "14",
-    },
-   Request{
-      Method: "15",
-    },
-   Request{
-      Method: "16",
-    },
-   Request{
-      Method: "17",
-    },
-   Request{
-      Method: "18",
-    },
-   Request{
-      Method: "19",
-    },
-     ...<80 more redacted>..
+     ...<86 more redacted>..
     },
   OneHttpRequest: Request{
     Method: "Hello",
   },
   EmptyString: "",
   SmallString: "What up?",
-  LargeString: "AT last the sleepy atmosphere was stirred—and vigorously: the murder trial came on in the court. It ...<3404 more redacted>..,
+  LargeString: "AT last the sleepy atmosphere was stirred—and vigorously: the murder trial came on in the ...<3414 more redacted>..,
   DistinctType: kama_test.Distance(9131),
   SomeNilError: error(nil),
   SomeConcreteError: error(Houston something bad happened),
@@ -125,13 +107,7 @@ SNIPPET: &SomeStruct{
    int(11),
    int(12),
    int(13),
-   int(14),
-   int(15),
-   int(16),
-   int(17),
-   int(18),
-   int(19),
-     ...<9980 more redacted>..
+     ...<9986 more redacted>..
     },
   LargeMap: map[int]string{
    int(0): "0", 
@@ -150,13 +126,7 @@ SNIPPET: &SomeStruct{
    int(1009): "1009", 
    int(101): "101", 
    int(1010): "1010", 
-   int(1011): "1011", 
-   int(1012): "1012", 
-   int(1013): "1013", 
-   int(1014): "1014", 
-   int(1015): "1015", 
-   int(1016): "1016", 
-   ...<9980 more redacted>..
+   ...<9986 more redacted>..
     },
   UndirectedChan: chan int (len=122, cap=10000),
   DirectedChan: chan<- bool (len=1, cap=13),

testdata/e2e_test/slice_in_a_struct_is_not_compacted.txt

@@ -23,13 +23,7 @@ SNIPPET: someStructWithSlice{
    int(11),
    int(12),
    int(13),
-   int(14),
-   int(15),
-   int(16),
-   int(17),
-   int(18),
-   int(19),
-     ...<9980 more redacted>..
+     ...<9986 more redacted>..
     },
 }
 ]