this is cool and all but the tables don't render properly

cmd/subnetter/consts.go

@@ -1,18 +1,103 @@
 package main
 
 import (
-	"github.com/go-playground/validator/v10"
+	`embed`
 	"strings"
+	`text/template`
+
+	"github.com/go-playground/validator/v10"
 )
 
 var (
-	args     *Args               = new(Args)
-	validate *validator.Validate = validator.New(validator.WithRequiredStructEnabled())
+	args     = new(Args)
+	validate = validator.New(validator.WithRequiredStructEnabled())
+)
+
+const (
+	/*
+		fixedPad is a fixed "surrounding" pad always present (as minimum), even for values max len on columns.
+		*Must* be positive even, as <fixed left pad> and <fixed right pad> == fixedPad/2.
+	*/
+	fixedPad int = 2
+	/*
+		padChars is what fills the pads in table cells.
+		At the *LEAST*, a cell will be "<fixedPad/2 * padChars><str><fixedPad/2 * padChars>"
+	*/
+	padChars string = " "
 )
 
 var (
-	sectSepCnt int    = 48
-	sectSep1   string = strings.Repeat("=", sectSepCnt)
-	sectSep2   string = strings.Repeat("-", sectSepCnt)
-	sectSep3   string = strings.Repeat(".", sectSepCnt)
+	//go:embed "_tpl"
+	tplDir embed.FS
+	tblTpl *template.Template = template.Must(template.New("").Funcs(
+		template.FuncMap{
+			"legacy4": tplClass4Iter,
+			"addrs":   tplAddrIter,
+			"mask4":   tplMaskIter4,
+		},
+	).ParseFS(tplDir, "_tpl/*.tpl"))
+)
+
+var (
+	// Primarily output formatting stuff in this block.
+	sectSepCnt = 48
+	sectSep1   = strings.Repeat("=", sectSepCnt)
+	sectSep2   = strings.Repeat("-", sectSepCnt)
+	sectSep3   = strings.Repeat(".", sectSepCnt)
+	// tblFmts contains a lookup of map[<is plain>]*tableFormatter.
+	tblFmts map[bool]*tableFormatter = map[bool]*tableFormatter{
+		// Plaintext/ASCII-only
+		true: &tableFormatter{
+			TopLeftHdr:      "*", // Or _
+			TopFillHdr:      "*", // ""
+			TopColSepHdr:    "*", // ""
+			TopRightHdr:     "*", // ""
+			ColSepHdr:       "|",
+			BottomLeftHdr:   "*", // Or +
+			BottomFillHdr:   "*", // Or -
+			BottomColSepHdr: "*", // Or +
+			BottomRightHdr:  "*", // ""
+			Left:            "|",
+			Fill:            "-",
+			LineColSep:      "|",
+			LineLeft:        "|",
+			LineRight:       "|",
+			ColSep:          "|",
+			Right:           "|",
+			LastLeft:        "+",
+			LastFill:        "-",
+			LastSep:         "-",
+			LastRight:       "+",
+			SuppressLineSep: true,
+			NoUpperTitle:    false,
+			NoBoldTitle:     true,
+		},
+		// Unicode/UTF-8
+		// https://en.wikipedia.org/wiki/Box-drawing_characters
+		false: &tableFormatter{
+			TopLeftHdr:      "┏",
+			TopFillHdr:      "━",
+			TopColSepHdr:    "┳",
+			TopRightHdr:     "┓",
+			ColSepHdr:       "┃",
+			BottomLeftHdr:   "┣",
+			BottomFillHdr:   "━",
+			BottomColSepHdr: "╇",
+			BottomRightHdr:  "┫",
+			Left:            "┃",
+			Fill:            "─",
+			LineColSep:      "┼",
+			LineLeft:        "┠",
+			LineRight:       "┨",
+			ColSep:          "│",
+			Right:           "┃",
+			LastLeft:        "┗",
+			LastFill:        "━",
+			LastSep:         "┷",
+			LastRight:       "┛",
+			SuppressLineSep: false,
+			NoUpperTitle:    true,
+			NoBoldTitle:     false,
+		},
+	}
 )