expose DBus interface signal names as symbols
Enable a way to access the signal names of a given DBus interface as a
constexpr symbol via the header.
4 use-cases:
- printing error / debug logs with the signal name.
e.g. 'received signal ${SIGNAL_NAME}'
- matching on DBus signals in applications which do not yet use the PDI
generated bindings.
- preventing typos in DBus signal names
- estimating the impact of removing a given DBus signal from an
interface. When using these symbols, it would cause a build failure in
applications relying on the existence of that signal.
This change is similar to [1] and goes into the same direction.
Tested: Newly written unit test passes.
References:
[1] d2571922bfdb4f6b41ba4fbc45b8a4272793fd40
Change-Id: I9c20d744955c883302f349c5351dbdba1753466b
Signed-off-by: Alexander Hansen <alexander.hansen@9elements.com>
diff --git a/test/gen/test_signal_names.cpp b/test/gen/test_signal_names.cpp
new file mode 100644
index 0000000..be9bb12
--- /dev/null
+++ b/test/gen/test_signal_names.cpp
@@ -0,0 +1,47 @@
+#include "sdbusplus/asio/connection.hpp"
+#include "sdbusplus/bus/match.hpp"
+#include "server/Test2/common.hpp"
+
+#include <print>
+
+#include <gtest/gtest.h>
+
+void cb(sdbusplus::message_t& msg)
+{
+ // We can access the signal name as a symbol.
+ // The property name is constexpr.
+
+ constexpr auto sigName =
+ sdbusplus::common::server::Test2::signal_names::other_value_changed;
+
+ // The property name can be used as part of error logs.
+
+ std::println("signal {} received on path {}\n", sigName, msg.get_path());
+}
+
+int main()
+{
+ // If the signal is removed from the interface definition, it will cause a
+ // build failure in applications still using that signal. That can work
+ // even if the application is not (yet) using PDI-generated bindings for
+ // it's DBus interactions.
+
+ std::println(
+ "using signal {} \n",
+ sdbusplus::common::server::Test2::signal_names::other_value_changed);
+
+ EXPECT_EQ(
+ sdbusplus::common::server::Test2::signal_names::other_value_changed,
+ "OtherValueChanged");
+
+ boost::asio::io_context io;
+ sdbusplus::asio::connection conn(io);
+
+ std::string matchStr = std::format(
+ "type='signal',member={}",
+ sdbusplus::common::server::Test2::signal_names::other_value_changed);
+
+ auto match = sdbusplus::bus::match_t(conn, matchStr, cb);
+
+ return 0;
+}