Start a flag package based on generics (#20)

flag/flag.go

@@ -0,0 +1,44 @@
+// Package flag implements CLI flag defining and parsing functionality.
+package flag
+
+import (
+	"net"
+	"time"
+)
+
+// Flaggable is a type constraint that defines any type capable of being parsed as a command line flag.
+type Flaggable interface {
+	~int | ~int8 | ~int16 | ~int32 | ~int64 | ~uint | ~uint8 | ~uint16 | ~uint32 | ~uint64 | ~uintptr | ~float32 | ~float64 | ~string | ~bool | ~[]byte | time.Time | net.IPNet
+}
+
+// Flag represents a single command line flag.
+type Flag[T Flaggable] struct {
+	value T      // The actual stored value
+	name  string // The name of the flag as appears on the command line, e.g. "force" for a --force flag
+	usage string // One line description of the flag, e.g. "Force deletion without confirmation"
+	short string // Optional shorthand version of the flag, e.g. "f" for a -f flag
+}
+
+// New constructs and returns a new [Flag].
+//
+// The name should be as it appears on the command line, e.g. "force" for a --force flag. An optional
+// shorthand can be created by setting short to a single letter value, e.g. "f" to also create a -f version of "force".
+//
+// If you want the flag to be longhand only, pass "" for short.
+//
+//	flag.New("force", "f", false, "Force deletion without confirmation")
+func New[T Flaggable](name string, short string, value T, usage string) *Flag[T] {
+	// Default implementation
+	flag := &Flag[T]{
+		value: value,
+		name:  name,
+		usage: usage,
+		short: short,
+	}
+	return flag
+}
+
+// Value returns the flags current value.
+func (f *Flag[T]) Value() T {
+	return f.value
+}