basic sub-client implementation

Pilz.Net/Api/ApiClient.cs

@@ -8,6 +8,7 @@ namespace Pilz.Net.Api;
 public class ApiClient(string apiUrl) : IApiClient
 {
     protected readonly HttpClient httpClient = new();
+    protected readonly List<object> clients = [];
 
     public virtual string ApiUrl { get; } = apiUrl;
 
@@ -17,6 +18,23 @@ public class ApiClient(string apiUrl) : IApiClient
 
     public ILogger Log { get; set; } = NullLogger.Instance;
 
+    public T GetClient<T>() where T : IApiSubClient
+    {
+        foreach (var c in clients)
+        {
+            if (c is T t)
+                return t;
+        }
+
+        if (T.CreateClient<T>(this) is T client)
+        {
+            clients.Add(client);
+            return client;
+        }
+
+        throw new ApiException("Could not create an instance of this client.");
+    }
+
     public virtual async Task<ApiResponse> SendRequest(string route, HttpMethod method, ApiMessage? message, ApiParameterCollection? @params, IApiMessageSerializer? serializer)
     {
         serializer ??= Serializer;