Custom helper for coords attribute

attribute/coords.go

@@ -0,0 +1,19 @@
+package attribute
+
+import (
+	"strconv"
+	"strings"
+
+	"gitlab.codemonkeysoftware.net/b/hatmill"
+)
+
+func Coords(values ...float32) hatmill.Attrib {
+	s := make([]string, 0, len(values))
+	for _, value := range values {
+		s = append(s, strconv.FormatFloat(float64(value), 'G', -1, 32))
+	}
+	return hatmill.Attrib{
+		Key:   "coords",
+		Value: strings.Join(s, ","),
+	}
+}

attribute/coords_test.go

@@ -0,0 +1,40 @@
+package attribute_test
+
+import (
+	"testing"
+
+	"gitlab.codemonkeysoftware.net/b/hatmill/attribute"
+)
+
+func TestCoordsNumberFormat(t *testing.T) {
+	for _, testcase := range []struct {
+		name  string
+		f     float32
+		value string
+	}{
+		{name: "zero", f: 0, value: "0"},
+		{name: "integral", f: 45, value: "45"},
+		{name: "positive fractional, small positive exponent", f: 12.55, value: "12.55"},
+		{name: "positive fractional, large positive exponent", f: 1.55E+12, value: "1.55E+12"},
+		{name: "positive fractional, large negative exponent", f: 1.55E-12, value: "1.55E-12"},
+		{name: "negative fractional, small positive exponent", f: -12.55, value: "-12.55"},
+		{name: "negative fractional, large positive exponent", f: -1.55E+12, value: "-1.55E+12"},
+		{name: "negative fractional, large negative exponent", f: -1.55E-12, value: "-1.55E-12"},
+	} {
+		t.Run(testcase.name, func(t *testing.T) {
+			testAttribValue(t, attribute.Coords(testcase.f), testcase.value)
+		})
+	}
+}
+
+func TestCoordsCardinality(t *testing.T) {
+	t.Run("zero", func(t *testing.T) {
+		testAttribValue(t, attribute.Coords(), "")
+	})
+	t.Run("one", func(t *testing.T) {
+		testAttribValue(t, attribute.Coords(5), "5")
+	})
+	t.Run("many", func(t *testing.T) {
+		testAttribValue(t, attribute.Coords(5, 4, 3, 2, 1), "5,4,3,2,1")
+	})
+}

attribute/generated.go

@@ -154,14 +154,6 @@ func Controls() hatmill.Attrib {
 	}
 }
 
-// Coords creates a "coords" attribute
-func Coords(value string) hatmill.Attrib {
-	return hatmill.Attrib{
-		Key:   "coords",
-		Value: value,
-	}
-}
-
 // Crossorigin creates a "crossorigin" attribute
 func Crossorigin(value string) hatmill.Attrib {
 	return hatmill.Attrib{