Data Modeling Patterns

Iota Status

Iota constants give small state codes clear names without storing magic numbers in the code.

iota constants Keep the integer representation compact while using named constants at each decision point.

Iota Status

status
iota_status.go
Replay: real traced execution (multi-file project)
package main

import "fmt"

const (
	StatusDraft = iota
	StatusReview
	StatusPublished
)

func main() {
	var status = StatusReview
	label := "unknown"
	if status == StatusDraft {
		label = "draft"
	} else if status == StatusReview {
		label = "review"
	} else if status == StatusPublished {
		label = "published"
	}
	ready := status == StatusPublished

	fmt.Println("status=", status)
	fmt.Println("label=", label)
	fmt.Println("ready=", ready)
}

package main

import "fmt"

const (
	StatusDraft = iota
	StatusReview
	StatusPublished
)

func main() {
	var status = StatusDraft
	label := "unknown"
	if status == StatusDraft {
		label = "draft"
	} else if status == StatusReview {
		label = "review"
	} else if status == StatusPublished {
		label = "published"
	}
	ready := status == StatusPublished

	fmt.Println("status=", status)
	fmt.Println("label=", label)
	fmt.Println("ready=", ready)
}

package main

import "fmt"

const (
	StatusDraft = iota
	StatusReview
	StatusPublished
)

func main() {
	var status = StatusPublished
	label := "unknown"
	if status == StatusDraft {
		label = "draft"
	} else if status == StatusReview {
		label = "review"
	} else if status == StatusPublished {
		label = "published"
	}
	ready := status == StatusPublished

	fmt.Println("status=", status)
	fmt.Println("label=", label)
	fmt.Println("ready=", ready)
}

  1. status ← 1, StatusReview ← 1, label ← "unknown"

    11func main() {12  var status→ 1 = StatusReview→ 1 //@status=StatusDraft, StatusPublished13  label→ "unknown" := "unknown"14  if status == StatusDraft {

  2. label ← "review"

    15  label = "draft"16} else if status1 == StatusReview1 {17  label→ "review" = "review"18} else if status == StatusPublished {

  3. ready ← false

    20  }21  ready→ false := status1 == StatusPublished22223  fmt.Println("status=", status1)24  fmt.Println("label=", label"review")25  fmt.Println("ready=", readyfalse)26}
    outputstatus= 1
label= review
ready= false

  1. status ← 0, StatusDraft ← 0, label ← "unknown"

    11func main() {12  var status→ 0 = StatusDraft→ 013  label→ "unknown" := "unknown"14  if status == StatusDraft {

  2. label ← "draft"

    13label := "unknown"14if status0 == StatusDraft0 {15  label→ "draft" = "draft"16} else if status == StatusReview {

  3. ready ← false

    20  }21  ready→ false := status0 == StatusPublished22223  fmt.Println("status=", status0)24  fmt.Println("label=", label"draft")25  fmt.Println("ready=", readyfalse)26}
    outputstatus= 0
label= draft
ready= false

  1. status ← 2, StatusPublished ← 2, label ← "unknown"

    11func main() {12  var status→ 2 = StatusPublished→ 213  label→ "unknown" := "unknown"14  if status == StatusDraft {

  2. label ← "published"

    17  label = "review"18} else if status2 == StatusPublished2 {19  label→ "published" = "published"20}

  3. ready ← true

    20  }21  ready→ true := status2 == StatusPublished22223  fmt.Println("status=", status2)24  fmt.Println("label=", label"published")25  fmt.Println("ready=", readytrue)26}
    outputstatus= 2
label= published
ready= true