types

Common interface contracts and function adapters used across the foomo ecosystem. Each lifecycle interface ships with a small family of adapters so plain functions can satisfy it without writing wrapper structs.

Import

import "github.com/foomo/go/types"

Pattern

For each context-aware interface (e.g. Starter), the package provides:

• <Name>Func — adapts func()
• <Name>FuncErr — adapts func() error
• <Name>FuncCtx — adapts func(context.Context)
• <Name>FuncCtxErr — adapts func(context.Context) error
• As<Name>(v any) (<Name>, bool) — runtime type assertion that promotes any of the above (or an existing <Name>) into the interface

The function adapters never return errors when the underlying function has none, so wrapping a func() in <Name>Func is always safe.

Interfaces

Closer

type Closer interface {
	Close(ctx context.Context) error
}

Adapters: CloseFunc, CloseFuncErr, CloseFuncCtx, CloseFuncCtxErr. Helper: AsCloser.

Pinger

type Pinger interface {
	Ping(ctx context.Context) error
}

Adapters: PingFunc, PingFuncErr, PingFuncCtx, PingFuncCtxErr. Helper: AsPinger.

Shutdowner

type Shutdowner interface {
	Shutdown(ctx context.Context) error
}

Adapters: ShutdownFunc, ShutdownFuncErr, ShutdownFuncCtx, ShutdownFuncCtxErr. Helper: AsShutdowner.

Starter

type Starter interface {
	Start(ctx context.Context) error
}

Adapters: StartFunc, StartFuncErr, StartFuncCtx, StartFuncCtxErr. Helper: AsStarter.

Stopper

type Stopper interface {
	Stop(ctx context.Context) error
}

Adapters: StopFunc, StopFuncErr, StopFuncCtx, StopFuncCtxErr. Helper: AsStopper.

Unsubscriber

type Unsubscriber interface {
	Unsubscribe(ctx context.Context) error
}

Adapters: UnsubscribeFunc, UnsubscribeFuncErr, UnsubscribeFuncCtx, UnsubscribeFuncCtxErr. Helper: AsUnsubscriber.

Causer

type Causer interface {
	Cause() error
}

Implemented by errors that wrap an underlying cause, distinct from the chain unwrapped by errors.Unwrap. Adapter: CauserFunc. See errors.Cause for unwrapping through a chain of Causers.

Namer

type Namer interface {
	Name() string
}

Stringer

type Stringer interface {
	String() string
}

Example

package main

import (
	"context"
	"fmt"

	"github.com/foomo/go/types"
)

func main() {
	// Any of these forms can be promoted to a Starter.
	candidates := []any{
		func() { fmt.Println("plain") },
		func() error { fmt.Println("err"); return nil },
		func(ctx context.Context) { fmt.Println("ctx") },
		func(ctx context.Context) error { fmt.Println("ctx+err"); return nil },
	}

	for _, c := range candidates {
		s, ok := types.AsStarter(c)
		if !ok {
			continue
		}
		_ = s.Start(context.Background())
	}
}