8 files changed, 68 insertions, 25 deletions
diff --git a/Help/guide/tutorial/Step3/CMakeLists.txt b/Help/guide/tutorial/Step3/CMakeLists.txt
index 007770a..ac3e9f1 100644
--- a/Help/guide/tutorial/Step3/CMakeLists.txt
+++ b/Help/guide/tutorial/Step3/CMakeLists.txt
@@ -3,13 +3,16 @@ cmake_minimum_required(VERSION 3.10)
 # set the project name and version
 project(Tutorial VERSION 1.0)
 
+# TODO 4: Replace the following code by:
+# * Creating an interface library called tutorial_compiler_flags
+#   Hint: use add_library() with the INTERFACE signature
+# * Add compiler feature cxx_std_11 to tutorial_compiler_flags
+#   Hint: Use target_compile_features()
+
 # specify the C++ standard
 set(CMAKE_CXX_STANDARD 11)
 set(CMAKE_CXX_STANDARD_REQUIRED True)
 
-# should we use our own math functions
-option(USE_MYMATH "Use tutorial provided math implementation" ON)
-
 # configure a header file to pass some of the CMake settings
 # to the source code
 configure_file(TutorialConfig.h.in TutorialConfig.h)
@@ -17,16 +20,15 @@ configure_file(TutorialConfig.h.in TutorialConfig.h)
 # TODO 2: Remove EXTRA_INCLUDES list
 
 # add the MathFunctions library
-if(USE_MYMATH)
-  add_subdirectory(MathFunctions)
-  list(APPEND EXTRA_LIBS MathFunctions)
-  list(APPEND EXTRA_INCLUDES "${PROJECT_SOURCE_DIR}/MathFunctions")
-endif()
+add_subdirectory(MathFunctions)
+list(APPEND EXTRA_INCLUDES "${PROJECT_SOURCE_DIR}/MathFunctions")
 
 # add the executable
 add_executable(Tutorial tutorial.cxx)
 
-target_link_libraries(Tutorial PUBLIC ${EXTRA_LIBS})
+# TODO 5: Link Tutorial to tutorial_compiler_flags
+
+target_link_libraries(Tutorial PUBLIC MathFunctions)
 
 # TODO 3: Remove use of EXTRA_INCLUDES
 
diff --git a/Help/guide/tutorial/Step3/MathFunctions/CMakeLists.txt b/Help/guide/tutorial/Step3/MathFunctions/CMakeLists.txt
index 7bf05e0..0ffb9e1 100644
--- a/Help/guide/tutorial/Step3/MathFunctions/CMakeLists.txt
+++ b/Help/guide/tutorial/Step3/MathFunctions/CMakeLists.txt
@@ -1,5 +1,22 @@
-add_library(MathFunctions mysqrt.cxx)
+add_library(MathFunctions MathFunctions.cxx)
 
 # TODO 1: State that anybody linking to MathFunctions needs to include the
 # current source directory, while MathFunctions itself doesn't.
 # Hint: Use target_include_directories with the INTERFACE keyword
+
+# should we use our own math functions
+option(USE_MYMATH "Use tutorial provided math implementation" ON)
+if (USE_MYMATH)
+  target_compile_definitions(MathFunctions PRIVATE "USE_MYMATH")
+
+  # library that just does sqrt
+  add_library(SqrtLibrary STATIC
+              mysqrt.cxx
+              )
+
+  # TODO 7: Link SqrtLibrary to tutorial_compiler_flags
+
+  target_link_libraries(MathFunctions PUBLIC SqrtLibrary)
+endif()
+
+# TODO 6: Link MathFunctions to tutorial_compiler_flags
diff --git a/Help/guide/tutorial/Step3/MathFunctions/MathFunctions.cxx b/Help/guide/tutorial/Step3/MathFunctions/MathFunctions.cxx
new file mode 100644
index 0000000..dc28b4b
--- /dev/null
+++ b/Help/guide/tutorial/Step3/MathFunctions/MathFunctions.cxx
@@ -0,0 +1,19 @@
+#include "MathFunctions.h"
+
+#include <cmath>
+
+#ifdef USE_MYMATH
+#  include "mysqrt.h"
+#endif
+
+namespace mathfunctions {
+double sqrt(double x)
+{
+// which square root function should we use?
+#ifdef USE_MYMATH
+  return detail::mysqrt(x);
+#else
+  return std::sqrt(x);
+#endif
+}
+}
diff --git a/Help/guide/tutorial/Step3/MathFunctions/MathFunctions.h b/Help/guide/tutorial/Step3/MathFunctions/MathFunctions.h
index cd36bcc..d5c2f22 100644
--- a/Help/guide/tutorial/Step3/MathFunctions/MathFunctions.h
+++ b/Help/guide/tutorial/Step3/MathFunctions/MathFunctions.h
@@ -1 +1,5 @@
-double mysqrt(double x);
+#pragma once
+
+namespace mathfunctions {
+double sqrt(double x);
+}
diff --git a/Help/guide/tutorial/Step3/MathFunctions/mysqrt.cxx b/Help/guide/tutorial/Step3/MathFunctions/mysqrt.cxx
index abe767d..ba0ac64 100644
--- a/Help/guide/tutorial/Step3/MathFunctions/mysqrt.cxx
+++ b/Help/guide/tutorial/Step3/MathFunctions/mysqrt.cxx
@@ -1,7 +1,9 @@
-#include <iostream>
+#include "mysqrt.h"
 
-#include "MathFunctions.h"
+#include <iostream>
 
+namespace mathfunctions {
+namespace detail {
 // a hack square root calculation using simple operations
 double mysqrt(double x)
 {
@@ -22,3 +24,5 @@ double mysqrt(double x)
   }
   return result;
 }
+}
+}
diff --git a/Help/guide/tutorial/Step3/MathFunctions/mysqrt.h b/Help/guide/tutorial/Step3/MathFunctions/mysqrt.h
new file mode 100644
index 0000000..593d41e
--- /dev/null
+++ b/Help/guide/tutorial/Step3/MathFunctions/mysqrt.h
@@ -0,0 +1,7 @@
+#pragma once
+
+namespace mathfunctions {
+namespace detail {
+double mysqrt(double x);
+}
+}
diff --git a/Help/guide/tutorial/Step3/TutorialConfig.h.in b/Help/guide/tutorial/Step3/TutorialConfig.h.in
index e23f521..7e4d7fa 100644
--- a/Help/guide/tutorial/Step3/TutorialConfig.h.in
+++ b/Help/guide/tutorial/Step3/TutorialConfig.h.in
@@ -1,4 +1,3 @@
 // the configured options and settings for Tutorial
 #define Tutorial_VERSION_MAJOR @Tutorial_VERSION_MAJOR@
 #define Tutorial_VERSION_MINOR @Tutorial_VERSION_MINOR@
-#cmakedefine USE_MYMATH
diff --git a/Help/guide/tutorial/Step3/tutorial.cxx b/Help/guide/tutorial/Step3/tutorial.cxx
index b3c6a4f..a3a2bdc 100644
--- a/Help/guide/tutorial/Step3/tutorial.cxx
+++ b/Help/guide/tutorial/Step3/tutorial.cxx
@@ -3,13 +3,9 @@
 #include <iostream>
 #include <string>
 
+#include "MathFunctions.h"
 #include "TutorialConfig.h"
 
-// should we include the MathFunctions header?
-#ifdef USE_MYMATH
-#  include "MathFunctions.h"
-#endif
-
 int main(int argc, char* argv[])
 {
   if (argc < 2) {
@@ -23,12 +19,7 @@ int main(int argc, char* argv[])
   // convert input to double
   const double inputValue = std::stod(argv[1]);
 
-  // which square root function should we use?
-#ifdef USE_MYMATH
-  const double outputValue = mysqrt(inputValue);
-#else
-  const double outputValue = sqrt(inputValue);
-#endif
+  const double outputValue = mathfunctions::sqrt(inputValue);
 
   std::cout << "The square root of " << inputValue << " is " << outputValue
             << std::endl;