Example using the library via FetchContent (#6)

Author: havogt

example/simple/CMakeLists.txt

@@ -10,3 +10,4 @@ gt_add_bindings_library(simple SOURCES simple.cpp)
 # 3) link the library to a fortran executable
 add_executable(driver driver.f90)
 target_link_libraries(driver simple_fortran)
+

example/simple_fetch_content/.gitignore

@@ -0,0 +1,3 @@
+simple.f90
+simple.h
+

example/simple_fetch_content/CMakeLists.txt

@@ -0,0 +1,27 @@
+cmake_minimum_required(VERSION 3.12.4) #TODO replace with generated version
+project(simple_example_with_fetch_content LANGUAGES CXX Fortran)
+
+# 1) fetch c_bindings from the repository
+# TODO: use FetchContent_MakeAvailable() once we require CMake 3.14+
+include(FetchContent)
+FetchContent_Declare(
+  c_bindings
+  # In your application remove SOURCE_DIR ...
+  SOURCE_DIR       ${CMAKE_CURRENT_LIST_DIR}/../..
+  # By the following 2 lines to fetch content directly from github
+  # GIT_REPOSITORY https://github.com/GridTools/c_bindings.git
+  # GIT_TAG        master # consider replacing master by a tagged version
+)
+FetchContent_GetProperties(c_bindings)
+if(NOT c_bindings_POPULATED)
+  FetchContent_Populate(c_bindings)
+  add_subdirectory(${c_bindings_SOURCE_DIR} ${c_bindings_BINARY_DIR})
+endif()
+
+# 2) create a library with bindings. This will generate the files simple.h and simple.f90 which can be included within C and Fortran. In CMake you can use them by linking against `simple_c`or `simple_fortran`.
+gt_add_bindings_library(simple SOURCES simple.cpp)
+
+# 3) link the generated library to a fortran executable
+add_executable(driver driver.f90)
+target_link_libraries(driver simple_fortran)
+

example/simple_fetch_content/driver.f90

@@ -0,0 +1,18 @@
+! GridTools
+!
+! Copyright (c) 2014-2019, ETH Zurich
+! All rights reserved.
+!
+! Please, refer to the LICENSE file in the root directory.
+! SPDX-License-Identifier: BSD-3-Clause
+
+program main
+    use iso_c_binding
+    use gt_handle
+    use simple
+    implicit none
+    integer, parameter :: i = 9
+
+    call print_number_from_cpp(i)
+
+end

example/simple_fetch_content/simple.cpp

@@ -0,0 +1,23 @@
+/*
+ * GridTools
+ *
+ * Copyright (c) 2014-2019, ETH Zurich
+ * All rights reserved.
+ *
+ * Please, refer to the LICENSE file in the root directory.
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <c_bindings/export.hpp>
+#include <iostream>
+
+// In this example, we demonstrate how the c_bindings library can be used to export functions to C and Fortran.
+
+namespace {
+    void print_number(int i) {
+        std::cout << "Printing from C++: " << i << std::endl;
+    }
+
+    // Exports a unary function with the name `print_number_from_cpp`, which forwards to `print_number`.
+    GT_EXPORT_BINDING_1(print_number_from_cpp, print_number);
+} // namespace

jenkins/build.sh

@@ -38,13 +38,21 @@ cwd=$(pwd)
 # install c_bindings
 mkdir -p build && cd build
 cmake .. -DCMAKE_INSTALL_PREFIX=${cwd}/install
-nice -15 make -j8 install
+nice make -j8 install
 ctest .
 
 # compile examples using the installation
+# simple example using installation
 cd ${cwd}/example/simple
 mkdir -p build && cd build
 cmake .. -Dgt_c_bindings_DIR=${cwd}/install/lib/cmake
-nice -15 make -j8
+nice make -j8
+./driver
+
+# simple example using FetchContent
+cd ${cwd}/example/simple_fetch_content
+mkdir -p build && cd build
+cmake ..
+nice make -j8
 ./driver