forked from looplab/eventhorizon
/
commandbus.go
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/
commandbus.go
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// Copyright (c) 2014 - Max Ekman <max@looplab.se>
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package eventhorizon
import (
"context"
"errors"
)
// ErrHandlerAlreadySet is when a handler is already registered for a command.
var ErrHandlerAlreadySet = errors.New("handler is already set")
// ErrHandlerNotFound is when no handler can be found.
var ErrHandlerNotFound = errors.New("no handlers for command")
// CommandHandler is an interface that all handlers of commands should implement.
type CommandHandler interface {
HandleCommand(context.Context, Command) error
}
// CommandBus is a command handler that delegates command handling to other
// handlers based on the command type.
type CommandBus interface {
CommandHandler
// SetHandler registers a handler for a command.
SetHandler(CommandHandler, CommandType) error
}