decode tables with values of custom type

[ecc1]

I expected to be able to decode a table into a map from string to a type of my choosing, as long as I provided an unmarshaling function for that type (like the duration example). But it doesn't seem to work.

Here's a program that I expect to panic during decoding:

package main

import (
	"fmt"

	"github.com/BurntSushi/toml"
)

type config struct {
	Sites map[string]custom
}

type custom struct {
	Value string
}

func main() {
	var conf config
	blob := `
	    [sites]

	    ebay   = "https://ebay.com"
	    google = "https://google.com"
	`
	toml.Decode(blob, &conf)
	fmt.Printf("% v\n", conf)
}

func (c *custom) UnmarshalText(text []byte) error {
	panic("unmarshal")
}

But the UnmarshalText function is never called, and the result is just {map[]}

Am I doing something wrong, or is this not possible?

[BurntSushi]

Looks like this might be a bug? If you use map[string]*custom instead of map[string]custom, then it works.

[cespare]

Yeah, it should work even though map values are not addressable.

[ecc1]

I tried with the *custom value, but then the UnmarshalText function gets called with a nil pointer as the receiver (so replacing the panic with something "useful" doesn't actually work). This version panics:

package main

import (
	"fmt"

	"github.com/BurntSushi/toml"
)

type config struct {
	Sites map[string]*custom
}

type custom struct {
	Value string
}

func main() {
	var conf config
	blob := `
	    [sites]

	    ebay   = "https://ebay.com"
	    google = "https://google.com"
	`
	toml.Decode(blob, &conf)
	fmt.Printf("% v\n", conf)
}

func (c *custom) UnmarshalText(text []byte) error {
	c.Value = string(text)
	return nil
}

[arp242]

Verified this is fixed now, for both examples.