refactor: use ostream in the error formatter (#136)

* refactor: inherit `fmt::formatter<errors::Error>` from `ostream_formatter`

* build: modify `errors_format` target to be interface library

Author: threeal

components/format/CMakeLists.txt

@@ -1,23 +1,22 @@
 cpmaddpackage("gh:fmtlib/fmt#10.2.0")
 
-add_library(errors_format src/format.cpp)
+add_library(errors_format INTERFACE)
 target_sources(
   errors_format PUBLIC
   FILE_SET HEADERS
   BASE_DIRS include
   FILES include/errors/format.hpp
 )
-target_link_libraries(errors_format PUBLIC errors fmt)
+target_link_libraries(errors_format INTERFACE errors fmt)
 
 if(NOT_SUBPROJECT)
   if (BUILD_TESTING)
     # Append the main library properties instead of linking the library.
-    get_target_property(errors_format_SOURCES errors_format SOURCES)
     get_target_property(errors_format_HEADER_DIRS errors_format HEADER_DIRS)
-    get_target_property(errors_format_LIBRARIES errors_format LINK_LIBRARIES)
+    get_target_property(errors_format_LIBRARIES errors_format INTERFACE_LINK_LIBRARIES)
 
     # Build tests for the main library
-    add_executable(errors_format_test test/format_test.cpp ${errors_format_SOURCES})
+    add_executable(errors_format_test test/format_test.cpp)
     target_include_directories(errors_format_test PRIVATE ${errors_format_HEADER_DIRS})
     target_link_libraries(errors_format_test PRIVATE Catch2::Catch2WithMain ${errors_format_LIBRARIES})
 

components/format/include/errors/format.hpp

@@ -2,6 +2,7 @@
 
 #include <errors/error.hpp>
 #include <fmt/core.h>
+#include <fmt/ostream.h>
 
 namespace errors {
 
@@ -17,15 +18,6 @@ Error format(fmt::format_string<T...> fmt, T&&... args);
 
 }  // namespace errors
 
-namespace fmt {
-
-template <>
-struct formatter<errors::Error> {
-  format_parse_context::iterator parse(format_parse_context& ctx) const;
-  format_context::iterator format(const errors::Error& err,
-                                  format_context& ctx) const;
-};
-
-}  // namespace fmt
+template <> struct fmt::formatter<errors::Error> : ostream_formatter {};
 
 #include "format.ipp"