Split tawashi into lib+executable to enable unit testing

src/tawashi_implem/get_env.hpp

@@ -0,0 +1,39 @@
+/* Copyright 2017, Michele Santullo
+ * This file is part of "tawashi".
+ *
+ * "tawashi" is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * "tawashi" is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with "tawashi".  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+#include <boost/utility/string_ref.hpp>
+#include <string>
+#if !defined(_GNU_SOURCE)
+#	define _GNU_SOURCE
+#endif
+#include <cstddef>
+#include <utility>
+#include <boost/optional.hpp>
+
+namespace tawashi {
+	boost::optional<std::string> get_env (const char* parName);
+
+	template <typename A>
+	A get_env_as (const char* parName, const A& parDefault);
+
+	template <>
+	std::string get_env_as (const char* parName, const std::string& parDefault);
+	template <>
+	std::size_t get_env_as (const char* parName, const std::size_t& parDefault);
+} //namespace tawashi