PowerShell Decorator Pattern: Enhance Logger with Timestamp and Uppercase

Logger-DecoratorPattern.ps1

class Logger {
    log($message) {  # Define a method called "log" that takes a message as input
        $message | Out-Host  # Output the message to the console
    }
}

class TimeStampingLogger : Logger {  # Define a class called "TimeStampingLogger" that inherits from "Logger"
    $logger  # Declare a variable called "logger"

    TimeStampingLogger($logger) {  # Define a constructor that takes a "logger" as input
        $this.logger = $logger  # Assign the input "logger" to the class variable "logger"
    }

    log($message) {  # Override the "log" method from the base class
        $now = Get-Date  # Get the current date and time
        $this.logger.log("$now : $message")  # Call the "log" method of the base class and prepend the timestamp to the message
    }
}

class UpperLogger : Logger {  # Define a class called "UpperLogger" that inherits from "Logger"
    $logger  # Declare a variable called "logger"

    UpperLogger($logger) {  # Define a constructor that takes a "logger" as input
        $this.logger = $logger  # Assign the input "logger" to the class variable "logger"
    }

    log($message) {  # Override the "log" method from the base class
        $this.logger.log($message.ToUpper())  # Call the "log" method of the base class and convert the message to uppercase
    }
}

$message = "Hello World"  # Define a variable called "message" and assign it the value "Hello World"

$logger = [Logger]::new()  # Create an instance of the "Logger" class and assign it to the variable "logger"
$logger.log($message)  # Call the "log" method of the "logger" instance with the "message" as input

$logger = [UpperLogger]::new([TimeStampingLogger]::new([Logger]::new()))  # Create an instance of the "UpperLogger" class with a nested instance of "TimeStampingLogger" and a "Logger" instance as inputs, and assign it to the variable "logger"
$logger.log($message)  # Call the "log" method of the "logger" instance with the "message" as input

$logger = [TimeStampingLogger]::new([Logger]::new())  # Create an instance of the "TimeStampingLogger" class with a "Logger" instance as input, and assign it to the variable "logger"
$logger.log($message)  # Call the "log" method of the "logger" instance with the "message" as input

That is very helpful! Thanks for sharing.