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// Copyright 2018 The Wire Authors
//
// 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
//
// https://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.
// The greeter binary simulates an event with greeters greeting guests.
package main
import (
"errors"
"fmt"
"os"
"time"
)
// Message is what greeters will use to greet guests.
type Message string
// NewMessage creates a default Message.
func NewMessage(phrase string) Message {
return Message(phrase)
}
// NewGreeter initializes a Greeter. If the current epoch time is an even
// number, NewGreeter will create a grumpy Greeter.
func NewGreeter(m Message) Greeter {
var grumpy bool
if time.Now().Unix()%2 == 0 {
grumpy = true
}
return Greeter{Message: m, Grumpy: grumpy}
}
// Greeter is the type charged with greeting guests.
type Greeter struct {
Grumpy bool
Message Message
}
// Greet produces a greeting for guests.
func (g Greeter) Greet() Message {
if g.Grumpy {
return Message("Go away!")
}
return g.Message
}
// NewEvent creates an event with the specified greeter.
func NewEvent(g Greeter) (Event, error) {
if g.Grumpy {
return Event{}, errors.New("could not create event: event greeter is grumpy")
}
return Event{Greeter: g}, nil
}
// Event is a gathering with greeters.
type Event struct {
Greeter Greeter
}
// Start ensures the event starts with greeting all guests.
func (e Event) Start() {
msg := e.Greeter.Greet()
fmt.Println(msg)
}
func main() {
e, err := InitializeEvent("hi there!")
if err != nil {
fmt.Printf("failed to create event: %s\n", err)
os.Exit(2)
}
e.Start()
}
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