How to initialize RegistryKey variable

Question

I have a function (OpenSubKeySymLink) that receives this kind of variable: this RegistryKey key.
I don't know how to initialize it and pass it to the function.


public static RegistryKey OpenSubKeySymLink(this RegistryKey key, string name, RegistryRights rights = RegistryRights.ReadKey, RegistryView view = 0)
{
    var error = RegOpenKeyExW(key.Handle, name, REG_OPTION_OPEN_LINK, ((int)rights) | ((int)view), out var subKey);
    if (error != 0)
    {
        subKey.Dispose();
        throw new Win32Exception(error);
    }
    return RegistryKey.FromHandle(subKey);  // RegistryKey will dispose subKey
}


static void Main(string[] args)
{
    RegistryKey key;  // how to initialize it?
    OpenSubKeySymLink(key, @"HKEY_CURRENT_USER\SOFTWARE\Microsoft\myKey", RegistryRights.ReadKey, 0);
}

Looks like an extension method. In which case you don't explicitly pass the first parameter, in this instance `key`. That's implicitly passed with the object you call the method on. — sticky bit, Jan 09 '22 at 15:42
Use one of the static members of the `Registry` class, see https://learn.microsoft.com/en-us/dotnet/api/microsoft.win32.registry — Anand Sowmithiran, Jan 09 '22 at 15:45

score 2 · Accepted Answer · answered Jan 09 '22 at 15:42

I apologize, I didn't fully explain how to use this code in my previous answer.

I wrote it as an extension, so you can call it on either an existing sub-key, or on one of the main keys, such as Registry.CurrentUser.

You would use it like this for example:

using (var key = Registry.CurrentUser.OpenSubKeySymLink(@"SOFTWARE\Microsoft\myKey", RegistryRights.ReadKey))
{
    // do stuff with key
}

You can obviously still use it as a non-extension function

using (var key = OpenSubKeySymLink(Registry.CurrentUser, @"SOFTWARE\Microsoft\myKey", RegistryRights.ReadKey))
{
    // do stuff with key
}

Note the optional parameters, which means that some parameters don't need to be passed as they have defaults.
Note the use of using on the returned key, in order to dispose it correctly.

Thank you, for the explanation, it works. I didn't want to comment this on the previous question as I considered it as a separate question that can maybe help other. Thank you! — E235, Jan 09 '22 at 15:48

How to initialize RegistryKey variable

1 Answers1