Created
December 11, 2016 08:05
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Go言語のChain Of Responsibilityパターンの実装
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package main | |
import "fmt" | |
const ( | |
ERR = 3 | |
NOTICE = 5 | |
DEBUG = 7 | |
) | |
type Logger interface { | |
WriteMessage(msg string) | |
} | |
type ChainLogger struct { | |
logger Logger | |
next *ChainLogger | |
mask int | |
} | |
func NewChainLogger(mask int, logger Logger) *ChainLogger { | |
return &ChainLogger{logger, nil, mask} | |
} | |
func (self *ChainLogger) SetNext(nextChainLogger *ChainLogger) *ChainLogger { | |
if self.next == nil { | |
self.next = nextChainLogger | |
} else { | |
self.next.SetNext(nextChainLogger) | |
} | |
return self | |
} | |
func (self *ChainLogger) Message(msg string, priority int) { | |
if priority <= self.mask { | |
self.logger.WriteMessage(msg) | |
if self.next != nil { | |
self.next.Message(msg, priority) | |
} | |
} | |
} | |
type StdoutLogger struct { | |
} | |
func (self *StdoutLogger) WriteMessage(msg string) { | |
fmt.Println("Writting to stdout: ", msg) | |
} | |
type EmailLogger struct { | |
} | |
func (self *EmailLogger) WriteMessage(msg string) { | |
fmt.Println("Sending via email :", msg) | |
} | |
type StderrLogger struct { | |
} | |
func (self *StderrLogger) WriteMessage(msg string) { | |
fmt.Println("Sending to stderr :", msg) | |
} | |
func main() { | |
l := NewChainLogger(DEBUG, &StdoutLogger{}).SetNext( | |
NewChainLogger(NOTICE, &EmailLogger{})).SetNext( | |
NewChainLogger(ERR, &StderrLogger{})) | |
l.Message("Entering function y.", DEBUG) | |
l.Message("Step1 Completed.", NOTICE) | |
l.Message("Ab error has occurred.", ERR) | |
} |
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