add on-demand download script to release

.github/workflows/publish.yaml

@@ -13,13 +13,16 @@ jobs:
       - uses: actions/checkout@v1
 
       - name: Set CPM version by tag
-        run: sed "s/0.27.2-development-version/${GITHUB_REF/refs\/tags\/v}/g" cmake/CPM.cmake > CPM.cmake
+        run: |
+          mkdir dist
+          sed "s/0.27.2-development-version/${GITHUB_REF/refs\/tags\/v}/g" cmake/CPM.cmake > dist/CPM.cmake
+          sed "s/0.27.2-development-version/${GITHUB_REF/refs\/tags\/v}/g" cmake/get_cpm.cmake > dist/get_cpm.cmake
 
       - name: Upload CPM.cmake to release
         uses: svenstaro/upload-release-action@v1-release
         with:
           repo_token: ${{ secrets.GITHUB_TOKEN }}
-          file: CPM.cmake
-          asset_name: CPM.cmake
           tag: ${{ github.ref }}
+          file: dist/*.cmake
+          file_glob: true
           overwrite: true

cmake/get_cpm.cmake

@@ -0,0 +1,19 @@
+set(CPM_DOWNLOAD_VERSION 0.27.2-development-version)
+
+if(CPM_SOURCE_CACHE)
+  set(CPM_DOWNLOAD_LOCATION "${CPM_SOURCE_CACHE}/cpm/CPM_${CPM_DOWNLOAD_VERSION}.cmake")
+elseif(DEFINED ENV{CPM_SOURCE_CACHE})
+  set(CPM_DOWNLOAD_LOCATION "$ENV{CPM_SOURCE_CACHE}/cpm/CPM_${CPM_DOWNLOAD_VERSION}.cmake")
+else()
+  set(CPM_DOWNLOAD_LOCATION "${CMAKE_BINARY_DIR}/cmake/CPM_${CPM_DOWNLOAD_VERSION}.cmake")
+endif()
+
+if(NOT (EXISTS ${CPM_DOWNLOAD_LOCATION}))
+  message(STATUS "Downloading CPM.cmake to ${CPM_DOWNLOAD_LOCATION}")
+  file(DOWNLOAD
+       https://github.com/TheLartians/CPM.cmake/releases/download/v${CPM_DOWNLOAD_VERSION}/CPM.cmake
+       ${CPM_DOWNLOAD_LOCATION}
+  )
+endif()
+
+include(${CPM_DOWNLOAD_LOCATION})