log and format for wstrings.

support/hololens/ServoApp/strutils.h

@@ -0,0 +1,22 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
+
+#pragma once
+
+template <typename... Args>
+std::wstring format(const std::wstring &txt, Args... args) {
+  size_t size = swprintf(nullptr, 0, txt.c_str(), args...) + 1;
+  if (size <= 0) {
+    throw std::runtime_error("Error during formatting.");
+  }
+  auto ptr = new wchar_t[size];
+  swprintf(ptr, size, txt.c_str(), args...);
+  auto wstr = std::wstring(ptr);
+  delete ptr;
+  return wstr;
+}
+
+template <typename... Args> void log(const std::wstring &txt, Args... args) {
+  OutputDebugString((format(txt, args...) + L"\r\n").c_str());
+}