TOML, JSON and YAML return values do not implement cli.ValueSource needed for cli.NewValueSourceChain()

[bluntelk]

Hi there,

I am trying out the new v3 APIs and have run across a rough edge when following the documentation

URLs

• https://cli.urfave.org/migrate-v2-to-v3/#altsrc-has-been-moved-out-of-the-cli-library-into-its-own-repo
• https://cli.urfave.org/v3/examples/flags/

The documentation says we can just use

cli.StringFlag{
        Sources: cli.ValueSourceChain{
           Chain: {
                EnvVars("APP_LANG"),
                Files("/path/to/foo"),
                altsrc.JSON("foo", "/path/to/"),
           }                
        },
}

but doing that we get errors like

cannot use (altsrc.JSON("foo", "/path/to/")) (value of type cli.ValueSourceChain) as cli.ValueSource value in argument to cli.NewValueSourceChain: cli.ValueSourceChain does not implement cli.ValueSource (method GoString has pointer receiver)

Example Program

package main

import (
	"context"
	altsrc "github.com/urfave/cli-altsrc/v3"
	"github.com/urfave/cli/v3"
	"log/slog"
	"os"
)

func main() {
	app := cli.Command{
		Flags: []cli.Flag{
			&cli.StringFlag{
				Name: "test",
				Sources: cli.NewValueSourceChain(
					cli.EnvVar("TEST"),
					altsrc.JSON("test", "./config.json"),
				),
			},
		},
	}
	if err := app.Run(context.Background(), os.Args); err != nil {
		slog.Error("Error running app", "err", err)
	}
}

require (
	github.com/urfave/cli-altsrc/v3 v3.0.0-alpha2
	github.com/urfave/cli/v3 v3.0.0-beta1
)

[dearchap]

@bluntelk We've been re-arranging some code in this repo . Can you try with the latest version like this ?

package main

import (
	"context"
	"log/slog"
	"os"

	ajson "github.com/urfave/cli-altsrc/json"
	"github.com/urfave/cli/v3"
)

func main() {
	app := cli.Command{
		Flags: []cli.Flag{
			&cli.StringFlag{
				Name: "test",
				Sources: cli.NewValueSourceChain(
					cli.EnvVar("TEST"),
					ajson.JSON("test", "./config.json"),
				),
			},
		},
	}
	if err := app.Run(context.Background(), os.Args); err != nil {
		slog.Error("Error running app", "err", err)
	}
}