Better strategy to parse metadata

[cuducos]

Is your feature request related to a problem? Please describe.

We have this TODO:

slides/internal/meta/meta.go

Line 38 in 1968b71

// FIXME: This only works because we currently only have one option (theme),

Describe the solution you'd like

And I think that using *string instead of string would help us differentiate something not set in the header from things set to an empty string.

I added new, better examples below, so collapsed this block ; )

package main

import (
	"encoding/json"
	"fmt"
)

type Meta struct {
	Theme *string `json:"theme"`
}

var meta Meta

func printTheme(t Meta) {
	if meta.Theme == nil {
		fmt.Println("Theme not set")
	} else {
		fmt.Printf("Theme is %s", *meta.Theme)
	}
}

func main() {
	json.Unmarshal([]byte("{}"), &meta)
	printTheme(meta)

	json.Unmarshal([]byte(`{"theme": "dark"}`), &meta)
	printTheme(meta)
}

This outputs:

Theme not set
Theme is dark

[cuducos]

Maybe a better use case example:

package main

import (
	"encoding/json"
	"fmt"
)

type Meta struct {
	Theme *string `json:"theme"`
}

var meta1 Meta
var meta2 Meta
var meta3 Meta
var meta4 Meta

func printTheme(m *Meta, j string) {
	json.Unmarshal([]byte(j), m)

	if m.Theme == nil {
		fmt.Printf("Theme not set for %s\n", j)
	} else {
		fmt.Printf("Theme is %s for %s\n", *m.Theme, j)
	}
}

func main() {
	printTheme(&meta1, "{}")
	printTheme(&meta2, `{"theme": "dark"}`)
	printTheme(&meta3, `{"theme": ""}`)
	printTheme(&meta4, `{"notATheme": "dark"}`)
}

Output:

Theme not set for {}
Theme is dark for {"theme": "dark"}
Theme is  for {"theme": ""}
Theme not set for {"notATheme": "dark"}

[maaslalani]

This is a great idea!

[maaslalani]

@cuducos do you want me to implement this or would you like to while adding the author/date metadata. Looks like you have a good handle on this though!