add more functions

dontpanic.go

@@ -7,8 +7,47 @@ package dontpanic
 
 import (
 	"fmt"
+
+	"golang.org/x/exp/constraints"
 )
 
+// Deref invokes *p.
+// Returns an error if p is nil.
+func Deref[T any](p *T) (_ T, err error) {
+	defer Recover(&err)
+	return *p, nil
+}
+
+// Div returns x / y.
+// Returns an error if y is zero.
+func Div[N constraints.Integer | constraints.Float | constraints.Complex](x, y N) (_ N, err error) {
+	defer Recover(&err)
+	return x / y, nil
+}
+
+// Mod returns x % y.
+// Returns an error if y is zero.
+func Mod[N constraints.Integer](x, y N) (_ N, err error) {
+	defer Recover(&err)
+	return x % y, nil
+}
+
+// Send invokes ch <- v.
+// Returns an error if ch is closed.
+func Send[T any](ch chan T, v T) (err error) {
+	defer Recover(&err)
+	ch <- v
+	return nil
+}
+
+// Close invokes close(ch).
+// Returns an error if ch is nil or closed.
+func Close[T any](ch chan T) (err error) {
+	defer Recover(&err)
+	close(ch)
+	return nil
+}
+
 // SetMapIndex sets m[k] = v.
 // Returns an error if m is nil.
 func SetMapIndex[K comparable, V any, M ~map[K]V](m M, k K, v V) (err error) {
@@ -17,6 +56,29 @@ func SetMapIndex[K comparable, V any, M ~map[K]V](m M, k K, v V) (err error) {
 	return nil
 }
 
+// Make invokes make(S, size...).
+// Returns an error if length is negative or larger than capacity.
+//
+// Supports empty:
+//  MakeSlice()
+// or length n:
+//  MakeSlice(n)
+// or length n and capacity m:
+//  MakeSlice(n, m)
+func MakeSlice[E any, S ~[]E](size ...int) (_ S, err error) {
+	defer Recover(&err)
+	switch len(size) {
+	case 0:
+		return nil, nil
+	case 1:
+		return make([]E, size[0]), nil
+	case 2:
+		return make([]E, size[0], size[1]), nil
+	default:
+		return nil, fmt.Errorf("size: expected 0-2 arguments; found %d", len(size))
+	}
+}
+
 // SetSliceIndex sets s[i] = v.
 // Returns an error if i is out of range.
 func SetSliceIndex[E any, S ~[]E](s S, i int, v E) (err error) {
@@ -33,16 +95,16 @@ func SliceIndex[E any, S ~[]E](s S, i int) (_ E, err error) {
 }
 
 // Slice returns s[i:j:k].
+// Returns an error if indexes are out of range or too many are specified.
 //
-// Supports [:]
+// Supports s[:]
 //  Slice(s)
-// or [i:]
+// or s[i:]
 //  Slice(s, i)
-// or [i:j]
+// or s[i:j]
 //  Slice(s, i, j)
-// or [i:j:k]
+// or s[i:j:k]
 //  Slice(s, i, j, k)
-// Returns an error if indexes are out of range or too many are specified.
 func Slice[E any, S ~[]E](s S, ijk ...int) (_ S, err error) {
 	defer Recover(&err)
 	switch len(ijk) {
@@ -59,6 +121,13 @@ func Slice[E any, S ~[]E](s S, ijk ...int) (_ S, err error) {
 	}
 }
 
+// StringIndex returns s[i].
+// Returns an error if i is out of range.
+func StringIndex(s string, i int) (_ byte, err error) {
+	defer Recover(&err)
+	return s[i], nil
+}
+
 // Recover calls recover() and writes the result to err.
 func Recover(err *error) {
 	switch r := recover().(type) {

go.mod

@@ -1,3 +1,5 @@
 module github.com/phelmkamp/dontpanic
 
 go 1.18
+
+require golang.org/x/exp v0.0.0-20220428152302-39d4317da171

go.sum

@@ -0,0 +1,2 @@
+golang.org/x/exp v0.0.0-20220428152302-39d4317da171 h1:TfdoLivD44QwvssI9Sv1xwa5DcL5XQr4au4sZ2F2NV4=
+golang.org/x/exp v0.0.0-20220428152302-39d4317da171/go.mod h1:lgLbSvA5ygNOMpwM/9anMpWVlVJ7Z+cHWq/eFuinpGE=