Use gsl::span for argument pointer array

Author: florianbecker

README.md

@@ -24,3 +24,6 @@ make -j`nproc`
 
 ## Unixservice class
 - Main function to run as a unix daemon.
+
+## Dependencies
+Because no major compiler supports `std::span` yet the [Microsoft Guidelines Support Library](https://github.com/Microsoft/GSL) (aka GSL) is used for its span implementation (from which the standard version was defined).

cmake/clang_warnings.cmake

@@ -39,4 +39,7 @@ set(WARNING_FLAGS
   -Wno-c++98-compat # C++11
   -Wno-c++98-compat-pedantic # C++11
   -Wno-padded
+
+  # brew install microsoft gsl
+  -Wno-poison-system-directories
 )

cmake/find_package.cmake

@@ -27,3 +27,5 @@
 # OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #
+
+find_package(Microsoft.GSL CONFIG)

examples/pipe/CMakeLists.txt

@@ -33,3 +33,5 @@ project(pipe)
 add_executable(${PROJECT_NAME}
   main.cpp
 )
+
+target_link_libraries(${PROJECT_NAME} PRIVATE Microsoft.GSL::GSL)

examples/pipe/main.cpp

@@ -32,10 +32,16 @@
 #include <iostream>
 #include <vector>
 
+/* gsl header */
+#include <gsl/gsl>
+#include <gsl/span>
+
 int main( int argc, char **argv ) {
 
+  gsl::span<char *> args = { argv, static_cast<std::size_t>( argc ) };
+
   /* Usage: pipe RESULTCODE */
-  if ( argc != 2 ) {
+  if ( args.size() != 2 ) {
 
     return EXIT_FAILURE;
   }
@@ -46,5 +52,5 @@ int main( int argc, char **argv ) {
   fprintf( stderr, "This is fprintf( stderr ) text.\n" );
   printf( "This is printf text.\n" );
 
-  return std::stoi( argv[ 1 ] );
+  return std::stoi( gsl::at( args, 1 ) );
 }