Add getter mode for runtime environment variable overrides

Makefile

@@ -44,3 +44,7 @@ coverage:
 	go test -coverprofile=coverage.out ./...
 	go tool cover -html=coverage.out -o coverage.html
 	@echo "Coverage report generated: coverage.html"
+
+# Generate example code
+generate-example:
+	go generate ./example

cfgx.go

@@ -75,6 +75,12 @@ type GenerateOptions struct {
 	// MaxFileSize is the maximum size in bytes for files referenced with "file:" prefix.
 	// If zero, defaults to DefaultMaxFileSize (1 MB).
 	MaxFileSize int64
+
+	// Mode specifies the generation mode:
+	//   "static" - values baked at build time (default)
+	//   "getter" - generate getter methods with runtime env var overrides
+	// If empty, defaults to "static".
+	Mode string
 }
 
 // GenerateFromFile generates Go code from a TOML file and writes it to the output file.
@@ -131,8 +137,14 @@ func GenerateFromFile(opts *GenerateOptions) error {
 		maxFileSize = DefaultMaxFileSize
 	}
 
+	// Set default mode if not specified
+	mode := opts.Mode
+	if mode == "" {
+		mode = "static"
+	}
+
 	// Generate code
-	generated, err := GenerateWithOptions(data, packageName, opts.EnableEnv, inputDir, maxFileSize)
+	generated, err := GenerateWithOptions(data, packageName, opts.EnableEnv, inputDir, maxFileSize, mode)
 	if err != nil {
 		return fmt.Errorf("failed to generate code: %w", err)
 	}
@@ -166,7 +178,7 @@ func GenerateFromFile(opts *GenerateOptions) error {
 // Note: This function does not support file: references since no input directory is provided.
 // Use GenerateWithOptions for full file embedding support.
 func Generate(tomlData []byte, packageName string, enableEnv bool) ([]byte, error) {
-	return GenerateWithOptions(tomlData, packageName, enableEnv, "", DefaultMaxFileSize)
+	return GenerateWithOptions(tomlData, packageName, enableEnv, "", DefaultMaxFileSize, "static")
 }
 
 // GenerateWithOptions generates Go code from TOML data with full options support.
@@ -179,9 +191,10 @@ func Generate(tomlData []byte, packageName string, enableEnv bool) ([]byte, erro
 //   - enableEnv: Whether to enable environment variable override markers in generated code
 //   - inputDir: Directory to resolve file: references from (empty string to disable)
 //   - maxFileSize: Maximum file size in bytes for file: references (0 for default 1MB)
+//   - mode: Generation mode ("static" or "getter")
 //
 // Returns the generated Go code as bytes, or an error if generation fails.
-func GenerateWithOptions(tomlData []byte, packageName string, enableEnv bool, inputDir string, maxFileSize int64) ([]byte, error) {
+func GenerateWithOptions(tomlData []byte, packageName string, enableEnv bool, inputDir string, maxFileSize int64, mode string) ([]byte, error) {
 	if packageName == "" {
 		packageName = "config"
 	}
@@ -190,11 +203,16 @@ func GenerateWithOptions(tomlData []byte, packageName string, enableEnv bool, in
 		maxFileSize = DefaultMaxFileSize
 	}
 
+	if mode == "" {
+		mode = "static"
+	}
+
 	gen := generator.New(
 		generator.WithPackageName(packageName),
 		generator.WithEnvOverride(enableEnv),
 		generator.WithInputDir(inputDir),
 		generator.WithMaxFileSize(maxFileSize),
+		generator.WithMode(mode),
 	)
 
 	return gen.Generate(tomlData)

cmd/cfgx/main.go

@@ -25,6 +25,7 @@ var (
 	packageName string
 	noEnv       bool
 	maxFileSize string
+	mode        string
 )
 
 func main() {
@@ -104,6 +105,11 @@ var generateCmd = &cobra.Command{
 			return fmt.Errorf("--out flag is required")
 		}
 
+		// Validate mode
+		if mode != "static" && mode != "getter" {
+			return fmt.Errorf("invalid --mode value %q: must be 'static' or 'getter'", mode)
+		}
+
 		// Parse max file size
 		maxFileSizeBytes, err := parseFileSize(maxFileSize)
 		if err != nil {
@@ -117,6 +123,7 @@ var generateCmd = &cobra.Command{
 			PackageName: packageName,
 			EnableEnv:   !noEnv,
 			MaxFileSize: maxFileSizeBytes,
+			Mode:        mode,
 		}
 
 		if err := cfgx.GenerateFromFile(opts); err != nil {
@@ -155,6 +162,7 @@ func init() {
 	generateCmd.Flags().StringVarP(&packageName, "pkg", "p", "", "package name (default: inferred from output path or 'config')")
 	generateCmd.Flags().BoolVar(&noEnv, "no-env", false, "disable environment variable overrides")
 	generateCmd.Flags().StringVar(&maxFileSize, "max-file-size", "1MB", "maximum file size for file: references (e.g., 10MB, 1GB, 512KB)")
+	generateCmd.Flags().StringVar(&mode, "mode", "static", "generation mode: 'static' (values baked at build time) or 'getter' (runtime env var overrides)")
 
 	generateCmd.MarkFlagRequired("out")
 

example/gen.go

@@ -1,3 +1,4 @@
 package main
 
 //go:generate go run ../cmd/cfgx/main.go generate --in config/config.toml --out config/config.go --pkg config
+//go:generate go run ../cmd/cfgx/main.go generate --in config/config.toml --out getter_config/config.go --pkg getter_config --mode getter