only include CPM when needed

Author: prevter

CMakeLists.txt

@@ -3,7 +3,6 @@ cmake_minimum_required(VERSION 3.21)
 project(discord-rpc)
 
 set(CMAKE_CXX_STANDARD 23)
-include(cmake/CPM.cmake)
 
 add_library(${PROJECT_NAME} STATIC src/discord-rpc.cpp src/serialization.cpp src/command-queue.cpp)
 target_include_directories(${PROJECT_NAME} PUBLIC include)
@@ -14,11 +13,16 @@ if (WIN32)
   target_link_libraries(${PROJECT_NAME} PRIVATE ws2_32.lib)
 endif()
 
-if (NOT TARGET fmt::fmt)
-  CPMAddPackage("gh:fmtlib/fmt#11.2.0")
-endif()
-if (NOT TARGET glaze::glaze)
-  CPMAddPackage("gh:stephenberry/glaze@5.5.4")
+if (NOT TARGET fmt::fmt OR NOT TARGET glaze::glaze)
+  if (NOT COMMAND CPMAddPackage)
+    include(cmake/CPM.cmake)
+  endif()
+  if (NOT TARGET fmt::fmt)
+    CPMAddPackage("gh:fmtlib/fmt#11.2.0")
+  endif()
+  if (NOT TARGET glaze::glaze)
+    CPMAddPackage("gh:stephenberry/glaze@5.5.4")
+  endif()
 endif()
 
 target_link_libraries(${PROJECT_NAME} PRIVATE fmt glaze::glaze)