README.adoc: example programs updated

README.adoc

@@ -63,18 +63,17 @@ package main
 import (
 	"fmt"
 	"strings"
-
 	"git.portale-stac.it/go-pkg/expr"
 )
 
 func main() {
 	ctx := expr.NewSimpleVarStore()
-	ctx.SetValue("var", int64(4))
+	ctx.SetVar("var", int64(4))
 
 	source := `(3-1)*(10/5) == var`
 
 	r := strings.NewReader(source)
-    scanner := expr.NewScanner(r, DefaultTranslations())
+	scanner := expr.NewScanner(r, expr.DefaultTranslations())
 	parser := expr.NewParser(ctx)
 
 	if ast, err := parser.Parse(scanner); err == nil {
@@ -88,10 +87,13 @@ func main() {
 	}
 }
 ----
+
 The above program is equivalent to the following one.
 
 [source,go]
 ----
+package main
+
 import (
 	"fmt"
 	"git.portale-stac.it/go-pkg/expr"
@@ -99,7 +101,7 @@ import (
 
 func main() {
 	ctx := expr.NewSimpleVarStore()
-	ctx.SetValue("var", int64(4))
+	ctx.SetVar("var", int64(4))
 
 	source := `(3-1)*(10/5) == var`
 
@@ -111,6 +113,29 @@ func main() {
 }
 ----
 
+Here is another equivalent version.
+
+[source,go]
+----
+package main
+
+import (
+	"fmt"
+
+	"git.portale-stac.it/go-pkg/expr"
+)
+
+func main() {
+	source := `(3-1)*(10/5) == var`
+
+	if result, err := expr.EvalStringA(source, expr.Arg{"var", int64(4)}); err == nil {
+		fmt.Printf("%q -> %v [%T]\n", source, result, result)
+	} else {
+		fmt.Println("Error calculating the expression:", err)
+	}
+}
+----
+
 === Data types
 _Expr_ supports numerical, string, relational, boolean expressions, and mixed-type lists.
 

helpers.go

@@ -19,35 +19,35 @@ func EvalString(ctx ExprContext, source string) (result any, err error) {
 	return
 }
 
-type EvalArg struct {
-	name  string
-	value any
+type Arg struct {
+	Name  string
+	Value any
 }
 
-func EvalStringA(source string, args ...EvalArg) (result any, err error) {
+func EvalStringA(source string, args ...Arg) (result any, err error) {
 	return EvalStringV(source, args)
 }
 
-func EvalStringV(source string, args []EvalArg) (result any, err error) {
+func EvalStringV(source string, args []Arg) (result any, err error) {
 	ctx := NewSimpleFuncStore()
 	for _, arg := range args {
-		if isFunc(arg.value) {
-			if f, ok := arg.value.(FuncTemplate); ok {
+		if isFunc(arg.Value) {
+			if f, ok := arg.Value.(FuncTemplate); ok {
 				functor := &simpleFunctor{f: f}
-				ctx.RegisterFunc(arg.name, functor, 0, -1)
+				ctx.RegisterFunc(arg.Name, functor, 0, -1)
 			} else {
-				err = fmt.Errorf("invalid function specification: %q", arg.name)
+				err = fmt.Errorf("invalid function specification: %q", arg.Name)
 			}
-		} else if integer, ok := anyInteger(arg.value); ok {
-			ctx.SetVar(arg.name, integer)
-		} else if float, ok := anyFloat(arg.value); ok {
-			ctx.SetVar(arg.name, float)
-		} else if _, ok := arg.value.(string); ok {
-			ctx.SetVar(arg.name, arg.value)
-		} else if _, ok := arg.value.(bool); ok {
-			ctx.SetVar(arg.name, arg.value)
+		} else if integer, ok := anyInteger(arg.Value); ok {
+			ctx.SetVar(arg.Name, integer)
+		} else if float, ok := anyFloat(arg.Value); ok {
+			ctx.SetVar(arg.Name, float)
+		} else if _, ok := arg.Value.(string); ok {
+			ctx.SetVar(arg.Name, arg.Value)
+		} else if _, ok := arg.Value.(bool); ok {
+			ctx.SetVar(arg.Name, arg.Value)
 		} else {
-			err = fmt.Errorf("unsupported type %T specified for item %q", arg.value, arg.name)
+			err = fmt.Errorf("unsupported type %T specified for item %q", arg.Value, arg.Name)
 		}
 	}
 

helpers_test.go

@@ -24,7 +24,7 @@ func subtract(ctx ExprContext, name string, args []any) (result any, err error)
 func TestEvalStringA(t *testing.T) {
 
 	source := `a + b * subtract(4,2)`
-	args := []EvalArg{
+	args := []Arg{
 		{"a", uint8(1)},
 		{"b", int8(2)},
 		{"subtract", FuncTemplate(subtract)},