使用SwitchParameter的PowerShell自定义Cmdlet

Question

I have the following code, where I try to create a custom Cmdlet for PowerShell using C#. What I want to do with my custom cmdlet is that, user should call it with two parameters, from which first one should be -Text or -File or -Dir, and the next one should be a value, a string which specifies the value for text, or file, or directory. It works fine as long as I can see. But I'm just curious whether there is another simple method or more elegant method that I can use to achieve what I want. Or is my solution the simplest that it can get? By the way, SHA256Text, SHA256File, and SHA256Directory, are just custom functions that I have written, so don't worry about them.

using System;
using System.IO;
using System.Text;
using System.Security.Cryptography;
using System.Management.Automation;

namespace PSSL
{
    [Cmdlet(VerbsCommon.Get, "SHA256")]
    public class GetSHA256 : PSCmdlet
    {
        #region Members

        private bool text;
        private bool file;
        private bool directory;
        private string argument;

        #endregion

        #region Parameters

        [Parameter(Mandatory = true, Position = 0, ParameterSetName = "Text")]
        public SwitchParameter Text
        {
            get { return text; }
            set { text = value; }
        }

        [Parameter(Mandatory = true, Position = 0, ParameterSetName = "File")]
        public SwitchParameter File
        {
            get { return file; }
            set { file = value; }
        }

        [Parameter(Mandatory = true, Position = 0, ParameterSetName = "Directory")]
        public SwitchParameter Dir
        {
            get { return directory; }
            set { directory = value; }
        }

        [Parameter(Mandatory = true, Position = 1)]
        [ValidateNotNullOrEmpty]
        public string Argument
        {
            get { return argument; }
            set { argument = value; }
        }

        #endregion

        #region Override Methods

        protected override void ProcessRecord()
        {
            switch(ParameterSetName)
            {
                case "Text":
                    SHA256Text(argument);
                    break;

                case "File":
                    SHA256File(argument);
                    break;

                case "Directory":
                    SHA256Directory(argument);
                    break;

                default:
                    throw new ArgumentException("Error: Bad parameter name.");
            }
        }

        #endregion
    }
}

Answer 1

You could use parameter sets to ensure that the user is only able to specify one of -Text , -File , or -Dir in conjunction with -Argument . You should then make your switches (and argument) mandatory rather than optional. This would mean your ProcessRecord method would know that a switch has been specified and that an argument has been provided. Therefore, you could remove your usage output, which will be available via Powershell's built-in Get-Help cmdlet.