finish generation of flag types for altsrc package

rename package to fg (flag generator)

fg/main.go

@@ -25,10 +25,10 @@ type FlagType struct {
 	ParserCast     string `json:"parser_cast"`
 }
 
-var cliFlagTemplate = `// Code generated by fg; DO NOT EDIT.
+var flagTemplate = `// Code generated by fg; DO NOT EDIT.
 
 package {{ .PackageName }}
-
+{{ if eq .PackageName "cli" }}
 import (
 	"flag"
 	"strconv"
@@ -93,7 +93,42 @@ func lookup{{ $flag.Name }}(name string, set *flag.FlagSet) {{ if ne .ContextTyp
     }
     return {{ $flag.ContextDefault }}
 }
-{{- end }}`
+{{- end }}
+{{ else }}
+import (
+	"flag"
+    "github.com/urfave/cli"
+)
+
+{{ range $i, $flag := .Flags }}
+// {{ $flag.Name }}Flag is the flag type that wraps cli.{{ $flag.Name }}Flag to allow
+// for other values to be specified
+type {{ $flag.Name }}Flag struct {
+    cli.{{ $flag.Name }}Flag
+    set *flag.FlagSet
+}
+
+// New{{ $flag.Name }}Flag creates a new {{ $flag.Name }}Flag
+func New{{ $flag.Name }}Flag(fl cli.{{ $flag.Name }}Flag) *{{ $flag.Name }}Flag {
+    return &{{ $flag.Name }}Flag{ {{ $flag.Name }}Flag: fl, set: nil }
+}
+
+// Apply saves the flagSet for later usage calls, then calls
+// the wrapped {{ $flag.Name }}Flag.Apply
+func (f *{{ $flag.Name }}Flag) Apply(set *flag.FlagSet) {
+	f.set = set
+	f.{{ $flag.Name }}Flag.Apply(set)
+}
+
+// ApplyWithError saves the flagSet for later usage calls, then calls
+// the wrapped {{ $flag.Name }}Flag.ApplyWithError
+func (f *{{ $flag.Name }}Flag) ApplyWithError(set *flag.FlagSet) error {
+    f.set = set
+    return f.{{ $flag.Name }}Flag.ApplyWithError(set)
+}
+{{- end }}
+{{- end }}
+`
 
 func main() {
 	var packageName, inputPath, outputPath string
@@ -125,6 +160,8 @@ func main() {
 
 	app.Action = func(c *cli.Context) error {
 		var info CliFlagInfo
+		var tpl *template.Template
+
 		info.PackageName = packageName
 
 		inFile, err := os.Open(inputPath)
@@ -141,7 +178,7 @@ func main() {
 			log.Fatal(err)
 		}
 
-		tpl := template.Must(template.New("").Parse(cliFlagTemplate))
+		tpl = template.Must(template.New("").Parse(flagTemplate))
 
 		outFile, err := os.Create(outputPath)
 		if err != nil {