diff --git a/src/stdutils/include/stdutils/chrono.h b/src/stdutils/include/stdutils/chrono.h
index 18e95c8..be1f85d 100644
--- a/src/stdutils/include/stdutils/chrono.h
+++ b/src/stdutils/include/stdutils/chrono.h
@@ -7,6 +7,15 @@
 namespace stdutils {
 namespace chrono {
 
+// For example to measure a duration in milliseconds:
+//
+//  std::chrono::duration<float, std::milli> duration;
+//  {
+//      stdutils::chrono::DurationMeas meas(duration);
+//      // Do something
+//  }
+//  float duration_ms = time.count();
+//
 template<typename Rep, typename Period>
 class DurationMeas
 {
diff --git a/src/stdutils/include/stdutils/io.h b/src/stdutils/include/stdutils/io.h
index d39651b..c6f97c5 100644
--- a/src/stdutils/include/stdutils/io.h
+++ b/src/stdutils/include/stdutils/io.h
@@ -31,6 +31,7 @@ struct Severity
     static constexpr SeverityCode EXCPT = -1;
     static constexpr SeverityCode ERR   = 1;
     static constexpr SeverityCode WARN  = 2;
+    static constexpr SeverityCode INFO  = 3;
 };
 
 std::string_view str_severity_code(SeverityCode code);
@@ -48,6 +49,15 @@ using StreamParser = std::function<Ret(std::basic_istream<CharT, std::char_trait
 template <typename Ret, typename CharT>
 Ret open_and_parse_file(const std::filesystem::path& filepath, const StreamParser<Ret, CharT>& stream_parser, const stdutils::io::ErrorHandler& err_handler) noexcept;
 
+/**
+ * Save a file with a writer to std::basic_ostream
+ */
+template <typename Obj, typename CharT>
+using StreamWriter = std::function<void(std::basic_ostream<CharT, std::char_traits<CharT>>&, const Obj&, const stdutils::io::ErrorHandler&)>;
+
+template <typename Obj, typename CharT>
+void save_file(const std::filesystem::path& filepath, const StreamWriter<Obj, CharT>& stream_writer, const Obj& obj, const stdutils::io::ErrorHandler& err_handler) noexcept;
+
 /**
  * LineStream: A wrapper around std::getline to count line nb
  */
@@ -114,12 +124,14 @@ using SkipLineStream = Basic_SkipLineStream<char>;
 template <typename CharT>
 std::size_t countlines(std::basic_istream<CharT, std::char_traits<CharT>>& istream);
 
+
 //
 //
-// IMPLEMENTATION
+// Implementation
 //
 //
 
+
 template <typename Ret, typename CharT>
 Ret open_and_parse_file(const std::filesystem::path& filepath, const StreamParser<Ret, CharT>& stream_parser, const stdutils::io::ErrorHandler& err_handler) noexcept
 {
@@ -141,12 +153,37 @@ Ret open_and_parse_file(const std::filesystem::path& filepath, const StreamParse
     catch(const std::exception& e)
     {
         std::stringstream oss;
-        oss << "Exception: " << e.what();
+        oss << "stdutils::io::open_and_parse_file(): " << e.what();
         err_handler(stdutils::io::Severity::EXCPT, oss.str());
     }
     return Ret();
 }
 
+template <typename Obj, typename CharT>
+void save_file(const std::filesystem::path& filepath, const StreamWriter<Obj, CharT>& stream_writer, const Obj& obj, const stdutils::io::ErrorHandler& err_handler) noexcept
+{
+    try
+    {
+        std::basic_ofstream<CharT> outputstream(filepath);
+        if (outputstream.is_open())
+        {
+            stream_writer(outputstream, obj, err_handler);
+        }
+        else
+        {
+            std::stringstream oss;
+            oss << "Cannot open file " << filepath;
+            err_handler(stdutils::io::Severity::FATAL, oss.str());
+        }
+    }
+    catch(const std::exception& e)
+    {
+        std::stringstream oss;
+        oss << "stdutils::io::save_file(): " << e.what();
+        err_handler(stdutils::io::Severity::EXCPT, oss.str());
+    }
+}
+
 template <typename CharT>
 Basic_LineStream<CharT>::Basic_LineStream(stream_type& source)
     : m_stream(source)
diff --git a/src/stdutils/include/stdutils/span.h b/src/stdutils/include/stdutils/span.h
index a1ca3e8..539b28a 100644
--- a/src/stdutils/include/stdutils/span.h
+++ b/src/stdutils/include/stdutils/span.h
@@ -19,6 +19,12 @@ class span {};
 template <typename T>
 class span<T, dyn_extent, void>
 {
+public:
+    using element_type = T;
+    using value_type = std::remove_cv_t<T>;
+    using pointer = T*;
+    using const_pointer = const T*;
+
 public:
     span(T* ptr, std::size_t size) noexcept : m_ptr(ptr), m_size(size) { assert(m_ptr); }
     span(const span<T>&) noexcept = default;
@@ -51,6 +57,13 @@ template <typename T, std::size_t Sz>
 class span<T, Sz, std::enable_if_t<Sz != dyn_extent>>
 {
     using this_type = span<T, Sz, std::enable_if_t<Sz != dyn_extent>>;
+
+public:
+    using element_type = T;
+    using value_type = std::remove_cv_t<T>;
+    using pointer = T*;
+    using const_pointer = const T*;
+
 public:
     explicit span(T* ptr) noexcept : m_ptr(ptr) { assert(m_ptr); }
     span(const this_type&) noexcept = default;
diff --git a/src/stdutils/include/stdutils/string.h b/src/stdutils/include/stdutils/string.h
index 44911a8..ca2e1d9 100644
--- a/src/stdutils/include/stdutils/string.h
+++ b/src/stdutils/include/stdutils/string.h
@@ -26,19 +26,22 @@ std::string capitalize(const std::string& in);
  *      out << indent(2);           // Output 2 indentations
  */
 template <typename CharT>
-class BasicIndent : private std::basic_string<CharT>
+class BasicIndent
 {
 public:
     class Multi;
 
-    BasicIndent(std::size_t count, CharT ch = ' ') : std::basic_string<CharT>(count, ch) {}
+    BasicIndent(std::size_t count, CharT ch = ' ') : m_str(count, ch) {}
 
     Multi operator()(std::size_t factor) const { return Multi(*this, factor); }
 
     friend std::basic_ostream<CharT>& operator<<(std::basic_ostream<CharT>& out, const BasicIndent<CharT>& indent)
     {
-        return out << static_cast<const std::basic_string<CharT>&>(indent);
+        return out << indent.m_str;
     }
+
+private:
+    std::basic_string<CharT> m_str;
 };
 
 template <typename CharT>
diff --git a/src/stdutils/src/io.cpp b/src/stdutils/src/io.cpp
index 437bf0f..ee7ac70 100644
--- a/src/stdutils/src/io.cpp
+++ b/src/stdutils/src/io.cpp
@@ -17,13 +17,17 @@ std::string_view str_severity_code(SeverityCode code)
     {
         return "EXCPT";
     }
+    else if (code == Severity::ERR)
+    {
+        return "ERROR";
+    }
     else if (code == Severity::WARN)
     {
         return "WARNING";
     }
-    else if (code == Severity::ERR)
+    else if (code == Severity::INFO)
     {
-        return "ERROR";
+        return "INFO";
     }
     else
     {
diff --git a/src/tests/stdutils/src/test_io.cpp b/src/tests/stdutils/src/test_io.cpp
index 324c53f..260889e 100644
--- a/src/tests/stdutils/src/test_io.cpp
+++ b/src/tests/stdutils/src/test_io.cpp
@@ -1,3 +1,5 @@
+// Copyright (c) 2023 Pierre DEJOUE
+// This code is distributed under the terms of the MIT License
 #include <catch_amalgamated.hpp>
 
 #include <stdutils/io.h>
diff --git a/src/tests/stdutils/src/test_span.cpp b/src/tests/stdutils/src/test_span.cpp
index b8e68d9..e3da259 100644
--- a/src/tests/stdutils/src/test_span.cpp
+++ b/src/tests/stdutils/src/test_span.cpp
@@ -1,3 +1,5 @@
+// Copyright (c) 2023 Pierre DEJOUE
+// This code is distributed under the terms of the MIT License
 #include <catch_amalgamated.hpp>
 
 #include <stdutils/span.h>