Tutorial: Refactor MathFunctions code

Propagate the refactor in Step 10 MathFunctions through all of the
steps. Use MathFunctions/MathFunctions.cxx instead of Tutorial.cxx
to determine which sqrt library is called. Adds .h files which
correspond to their .cxx files by name.

Help/guide/tutorial/Step9/CMakeLists.txt

@@ -16,22 +16,17 @@ target_compile_options(tutorial_compiler_flags INTERFACE
   "$<${msvc_cxx}:$<BUILD_INTERFACE:-W3>>"
 )
 
-# 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)
 
 # add the MathFunctions library
-if(USE_MYMATH)
-  add_subdirectory(MathFunctions)
-  list(APPEND EXTRA_LIBS MathFunctions)
-endif()
+add_subdirectory(MathFunctions)
 
 # add the executable
 add_executable(Tutorial tutorial.cxx)
-target_link_libraries(Tutorial PUBLIC ${EXTRA_LIBS} tutorial_compiler_flags)
+
+target_link_libraries(Tutorial PUBLIC MathFunctions tutorial_compiler_flags)
 
 # add the binary tree to the search path for include files
 # so that we will find TutorialConfig.h

Help/guide/tutorial/Step9/MathFunctions/CMakeLists.txt

@@ -1,34 +1,49 @@
-# first we add the executable that generates the table
-add_executable(MakeTable MakeTable.cxx)
-
-# add the command to generate the source code
-add_custom_command(
-  OUTPUT ${CMAKE_CURRENT_BINARY_DIR}/Table.h
-  COMMAND MakeTable ${CMAKE_CURRENT_BINARY_DIR}/Table.h
-  DEPENDS MakeTable
-  )
-
-# add the main library
-add_library(MathFunctions
-            mysqrt.cxx
-            ${CMAKE_CURRENT_BINARY_DIR}/Table.h
-            )
+add_library(MathFunctions MathFunctions.cxx)
 
 # state that anybody linking to us needs to include the current source dir
 # to find MathFunctions.h, while we don't.
-# state that we depend on Tutorial_BINARY_DIR but consumers don't, as the
-# TutorialConfig.h include is an implementation detail
-# state that we depend on our binary dir to find Table.h
 target_include_directories(MathFunctions
-          INTERFACE ${CMAKE_CURRENT_SOURCE_DIR}
-          PRIVATE   ${CMAKE_CURRENT_BINARY_DIR}
-          )
+                           INTERFACE ${CMAKE_CURRENT_SOURCE_DIR}
+                           )
 
-# link our compiler flags interface library
-target_link_libraries(MathFunctions tutorial_compiler_flags)
+# 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")
+
+  # first we add the executable that generates the table
+  add_executable(MakeTable MakeTable.cxx)
+  target_link_libraries(MakeTable PRIVATE tutorial_compiler_flags)
+
+  # add the command to generate the source code
+  add_custom_command(
+    OUTPUT ${CMAKE_CURRENT_BINARY_DIR}/Table.h
+    COMMAND MakeTable ${CMAKE_CURRENT_BINARY_DIR}/Table.h
+    DEPENDS MakeTable
+    )
+
+  # library that just does sqrt
+  add_library(SqrtLibrary STATIC
+              mysqrt.cxx
+              ${CMAKE_CURRENT_BINARY_DIR}/Table.h
+              )
+
+  # state that we depend on our binary dir to find Table.h
+  target_include_directories(SqrtLibrary PRIVATE
+              ${CMAKE_CURRENT_BINARY_DIR}
+              )
+
+  target_link_libraries(SqrtLibrary PUBLIC tutorial_compiler_flags)
+  target_link_libraries(MathFunctions PRIVATE SqrtLibrary)
+endif()
+
+target_link_libraries(MathFunctions PUBLIC tutorial_compiler_flags)
 
 # install libs
 set(installable_libs MathFunctions tutorial_compiler_flags)
+if(TARGET SqrtLibrary)
+  list(APPEND installable_libs SqrtLibrary)
+endif()
 install(TARGETS ${installable_libs} DESTINATION lib)
 # install include headers
 install(FILES MathFunctions.h DESTINATION include)

Help/guide/tutorial/Step9/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
+}
+}

Help/guide/tutorial/Step9/MathFunctions/MathFunctions.h

@@ -1 +1,5 @@
-double mysqrt(double x);
+#pragma once
+
+namespace mathfunctions {
+double sqrt(double x);
+}

Help/guide/tutorial/Step9/MathFunctions/mysqrt.cxx

@@ -1,10 +1,12 @@
-#include <iostream>
+#include "mysqrt.h"
 
-#include "MathFunctions.h"
+#include <iostream>
 
 // include the generated table
 #include "Table.h"
 
+namespace mathfunctions {
+namespace detail {
 // a hack square root calculation using simple operations
 double mysqrt(double x)
 {
@@ -31,3 +33,5 @@ double mysqrt(double x)
 
   return result;
 }
+}
+}

Help/guide/tutorial/Step9/MathFunctions/mysqrt.h

@@ -0,0 +1,7 @@
+#pragma once
+
+namespace mathfunctions {
+namespace detail {
+double mysqrt(double x);
+}
+}

Help/guide/tutorial/Step9/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

Help/guide/tutorial/Step9/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;