Sample Console Application

This demonstration project stands up a console app that implements IHostBuilder to implement dependency injection. It also demonstrates usage of the CommandLineParser library for handling command line argument parsing.

In this demonstration project, IHostBuilder is overkill for what the functionality is. However, IHostBuilder can be useful if you are using code that is implemented via service extensions or if you are building a larger application in which dependency is required to make the code more readable/testable/etc.

License / Usage Rights

Use and distribute freely with our without attribution. No warranty or claims made as to functionality, bugs, fitness to purpose or any other intent.

Design Objectives

• Flexible command line argument processing
• Dependency injection
• Ability to output to Console and ILogger independently

Requirements

• Microsoft .NET 6 Core SDK

Demonstrated Functionality

This command line utilities performs two functions:

• Calculation (default): Evaluate the passed parameters and return the results.
• Statistics: Accepts a list of numbers and returns statistic information

By default, the return format is "plain text". You can optionally return data in JSON format by specifying "-f json"

Examples:

Executing via dotnet from project directory:

• dotnet run -- 100 + 200 / 2 (Returns 200)
• dotnet run -- "(100 + 200) / 2" (Returns 150, you'll need the quotes for parenthesis and asterisks)
• dotnet run -- calc 500 + 2 (Returns 502, the "calc" is unnecessary but shown for completeness)
• dotnet run -- -f json 100/2 (Returns {Value":50})
• dotnet run -- stats 100 200 300 400 500 (Returns Count=5, Mean=300, Variance=25000, StandardDeviation=158.11388300841898, Skewness=0, Kurtosis=-1.2000000000000002, Maximum=500, Minimum=100)
• dotnet run -- stats 100 200 300 400 500 (Returns Count=5, Mean=300, Variance=25000, StandardDeviation=158.11388300841898, Skewness=0, Kurtosis=-1.2000000000000002, Maximum=500, Minimum=100)
• dotnet run -- stats -f json 100 200 300 400 500: (Returns {"Count":5,"Mean":300,"Variance":25000,"StandardDeviation":158.11388300841898,"Skewness":0,"Kurtosis":-1.2000000000000002,"Maximum":500,"Minimum":100})

Basic Recipe

1. In IHostBuilder.ConfigureServices, define injections for any global services and call the default command argument parser's ParseArguments
2. For parsed options, define verb-specific services, including implementing ITaskFactory (which either implements what you want to do or throws an exception)
3. Returns zero on happy path or otherwise -1

This example executes some functionality and exits. Therefore, it does not implement IHostLifetime. If you are writing a service/daemon that is going to run persistently, you will want to implement IHostLifetime