learned I didn't need git for external modules and different folders can have different mains

pkg/calendar/date.go

@@ -0,0 +1,56 @@
+package calendar
+
+import "errors"
+
+// Date Struct
+type Date struct {
+	year  int
+	month int
+	day   int
+}
+
+// Setter Methods
+
+// SetYear Method
+func (d *Date) SetYear(year int) error {
+	if year < 1 {
+		return errors.New("invalid year")
+	}
+	d.year = year
+	return nil
+}
+
+// SetMonth Method
+func (d *Date) SetMonth(month int) error {
+	if month < 1 || month > 12 {
+		return errors.New("invalid month")
+	}
+	d.month = month
+	return nil
+}
+
+// SetDay Method
+func (d *Date) SetDay(day int) error {
+	if day < 1 || day > 31 {
+		return errors.New("invalid day")
+	}
+	d.day = day
+	return nil
+}
+
+// Getter Methods
+
+// Year Method
+func (d *Date) Year() int {
+	return d.year
+}
+
+// Month Method
+func (d *Date) Month() int {
+	return d.month
+}
+
+// Day Method
+func (d *Date) Day() int {
+	return d.day
+}

pkg/calendar/event.go

@@ -0,0 +1,23 @@
+package calendar
+
+import (
+	"errors"
+	"unicode/utf8"
+)
+
+type Event struct {
+	title string
+	Date
+}
+
+func (e *Event) Title() string {
+	return e.title
+}
+
+func (e *Event) SetTitle(title string) error {
+	if utf8.RuneCountInString(title) > 32 {
+		return errors.New("invalid title length")
+	}
+	e.title = title
+	return nil
+}

pkg/datafile/floats.go

@@ -0,0 +1,32 @@
+package datafile
+
+import (
+	"bufio"
+	"os"
+	"strconv"
+)
+
+// GetFloats reads a float64 from each line of a file.
+func GetFloats(fileName string) ([]float64, error) {
+	var numbers []float64
+	file, err := os.Open(fileName)
+	if err != nil {
+		return nil, err
+	}
+	scanner := bufio.NewScanner(file)
+	for scanner.Scan() {
+		number, err := strconv.ParseFloat(scanner.Text(), 64)
+		if err != nil {
+			return nil, err
+		}
+		numbers = append(numbers, number)
+	}
+	err = file.Close()
+	if err != nil {
+		return nil, err
+	}
+	if scanner.Err() != nil {
+		return numbers, scanner.Err()
+	}
+	return numbers, nil
+}

pkg/datafile/strings.go

@@ -0,0 +1,31 @@
+package datafile
+
+import (
+	"bufio"
+	"os"
+)
+
+func GetStrings(filename string) ([]string, error) {
+	var lines []string
+	file, err := os.Open(filename)
+	if err != nil {
+		return nil, err
+	}
+
+	scanner := bufio.NewScanner(file)
+	for scanner.Scan() {
+		line := scanner.Text()
+		lines = append(lines, line)
+	}
+
+	err = file.Close()
+	if err != nil {
+		return nil, err
+	}
+
+	if scanner.Err() != nil {
+		return nil, scanner.Err()
+	}
+
+	return lines, nil
+}

pkg/date/date.go

@@ -0,0 +1,56 @@
+package calendar
+
+import "errors"
+
+// Date Struct
+type Date struct {
+	year  int
+	month int
+	day   int
+}
+
+// Setter Methods
+
+// SetYear Method
+func (d *Date) SetYear(year int) error {
+	if year < 1 {
+		return errors.New("invalid year")
+	}
+	d.year = year
+	return nil
+}
+
+// SetMonth Method
+func (d *Date) SetMonth(month int) error {
+	if month < 1 || month > 12 {
+		return errors.New("invalid month")
+	}
+	d.month = month
+	return nil
+}
+
+// SetDay Method
+func (d *Date) SetDay(day int) error {
+	if day < 1 || day > 31 {
+		return errors.New("invalid day")
+	}
+	d.day = day
+	return nil
+}
+
+// Getter Methods
+
+// Year Method
+func (d *Date) Year() int {
+	return d.year
+}
+
+// Month Method
+func (d *Date) Month() int {
+	return d.month
+}
+
+// Day Method
+func (d *Date) Day() int {
+	return d.day
+}

pkg/date/event.go

@@ -0,0 +1,23 @@
+package calendar
+
+import (
+	"errors"
+	"unicode/utf8"
+)
+
+type Event struct {
+	title string
+	Date
+}
+
+func (e *Event) Title() string {
+	return e.title
+}
+
+func (e *Event) SetTitle(title string) error {
+	if utf8.RuneCountInString(title) > 32 {
+		return errors.New("invalid title length")
+	}
+	e.title = title
+	return nil
+}

pkg/gadget/program.go

@@ -0,0 +1,33 @@
+package main
+
+type Player interface {
+	Play(string)
+	Stop()
+}
+
+func TryOut(player Player) {
+	player.Play("Test Track")
+	player.Stop()
+	recorder, ok := player.(TapeRecorder)
+	if ok {
+		recorder.Record()
+	}
+}
+
+func playList(device Player, songs []string) {
+	for _, song := range songs {
+		device.Play(song)
+	}
+
+	device.Stop()
+}
+
+func main() {
+	mixTape := []string{"Jessie's Girl", "Whip It", "9 to 5"}
+	var player Player = TapePlayer{}
+	playList(player, mixTape)
+	player = TapeRecorder{}
+	playList(player, mixTape)
+	TryOut(TapeRecorder{})
+	TryOut(TapePlayer{})
+}

pkg/gadget/tape.go

@@ -0,0 +1,31 @@
+package main
+
+import "fmt"
+
+type TapePlayer struct {
+	Batteries string
+}
+
+func (t TapePlayer) Play(song string) {
+	fmt.Println("Playing", song)
+}
+
+func (t TapePlayer) Stop() {
+	fmt.Println("Stopped")
+}
+
+type TapeRecorder struct {
+	Microphone int
+}
+
+func (t TapeRecorder) Play(song string) {
+	fmt.Println("Playing", song)
+}
+
+func (t TapeRecorder) Record() {
+	fmt.Println("Recording")
+}
+
+func (t TapeRecorder) Stop() {
+	fmt.Println("Stopped")
+}

pkg/keyboard/keyboard.go

@@ -0,0 +1,38 @@
+// Package keyboard reads user input from the keyboard.
+package keyboard
+
+import (
+	"bufio"
+	"os"
+	"strconv"
+	"strings"
+)
+
+// GetString reads a string from the keyboard.
+// It returns the string read and any error encountered.
+func GetString() (string, error) {
+	reader := bufio.NewReader(os.Stdin)
+	input, err := reader.ReadString('\n')
+	if err != nil {
+		return "", err
+	}
+
+	return input, nil
+}
+
+// GetFloat reads a floating-point number from the keyboard.
+// It returns the number read and any error encountered.
+func GetFloat() (float64, error) {
+	input, err := GetString()
+	if err != nil {
+		return 0, err
+	}
+
+	input = strings.TrimSpace(input)
+	number, err := strconv.ParseFloat(input, 64)
+	if err != nil {
+		return 0, err
+	}
+
+	return number, nil
+}

pkg/magazine/types.go

@@ -0,0 +1,21 @@
+package magazine
+
+type Subscriber struct {
+	Name   string
+	Rate   float64
+	Active bool
+	Address
+}
+
+type Employee struct {
+	Name   string
+	Salary float64
+	Address
+}
+
+type Address struct {
+	Street     string
+	City       string
+	State      string
+	PostalCode string
+}