Offline comments for Richard Siddaway's Objective: Objects talk @ PSHSummit

objects.ps1

#region new()

# new() works not only on PS Classes, but wraps existing .NET ctors as well:
[System.Net.WebProxy]::new("proxyserver.contoso.com",3128)

#endregion

#region Add-Type

#region Access modifiers

# Add-Type and C# type and member defitions are not only useful for controlling accessibility levels:
$Definition = @'
public class MyClass {
    public string param1 { get; set; }
    private string param2 { get; set; }

    public MyClass() {
        this.param2 = "Not accessible from outside the class";
    }
}
'@

Add-Type -TypeDefinition $Definition

#endregion

#region property accessors

# But for defining custom accessors ("getters" and "setters") as well:
$Definition = @'
public class MyMathClass {

    private int square;
    public int Square
    {
        get { return this.square; }
        set { this.square = value * value; }
    }
}
'@

Add-Type -TypeDefinition $Definition

# What black magic is this?!
PS C:\> $myInstance = [MyMathClass]::new()
PS C:\> $myInstance.Square = 3
PS C:\> $myInstance.Square
9

#endregion

#region DllImport

# and finally: marshalling native code!
# PowerShell + the DllImport attribute + pinvoke.net = magic
$PingUtilityDefinition = @'
using System;
using System.Net;
using System.Runtime.InteropServices;

public class IcmpPing
{
    [StructLayout(LayoutKind.Sequential, CharSet=CharSet.Ansi)]
    private struct ICMP_OPTIONS
    {
        public byte Ttl;
        public byte Tos;
        public byte Flags;
        public byte OptionsSize;
        public IntPtr OptionsData;
    }

    [StructLayout(LayoutKind.Sequential, CharSet=CharSet.Ansi)]
    private struct ICMP_ECHO_REPLY
    {
        public int Address;
        public int Status;
        public int RoundTripTime;
        public short DataSize;
        public short Reserved;
        public IntPtr DataPtr;
        public ICMP_OPTIONS Options;
        [MarshalAs(UnmanagedType.ByValTStr, SizeConst=250)]
        public string Data;
    }

    [DllImport("icmp.dll", SetLastError=true)]
    private static extern IntPtr IcmpCreateFile();
    [DllImport("icmp.dll", SetLastError=true)]
    private static extern bool IcmpCloseHandle(IntPtr handle);
    [DllImport("icmp.dll", SetLastError=true)]
    private static extern int IcmpSendEcho(IntPtr icmpHandle, int destinationAddress, string requestData, short requestSize, ref ICMP_OPTIONS requestOptions, ref ICMP_ECHO_REPLY replyBuffer, int replySize, int timeout);

    public bool Ping(IPAddress ip)
    {
        IntPtr icmpHandle = IcmpCreateFile();
        ICMP_OPTIONS icmpOptions = new ICMP_OPTIONS();
        icmpOptions.Ttl = 255;
        ICMP_ECHO_REPLY icmpReply = new ICMP_ECHO_REPLY();
        string sData = "x";

        int iReplies = IcmpSendEcho(icmpHandle, BitConverter.ToInt32(ip.GetAddressBytes(), 0), sData, (short)sData.Length, ref icmpOptions, ref icmpReply, Marshal.SizeOf(icmpReply), 30);
        IcmpCloseHandle(icmpHandle);
        if (icmpReply.Status == 0)
            return true;
        return false;
    }
}
'@

Add-Type -TypeDefinition $PingUtilityDefinition 

# Now you can have the OS send an ICMP echo for you, just like ping.exe - incredibly low overhead:
PS C:\> [IcmpPing]::new().Ping("127.0.0.1")
True

# Example above is from http://pinvoke.net/default.aspx/icmp.IcmpSendEcho

#endregion

#endregion