...

examples/device_exam.cpp

@@ -13,15 +13,30 @@ int main()
     AdcGenericDevice<> dev;
 
     dev.addAttr(
-        "1", [&i]() { return adc_result_t<int>{i}; },
+        "1", [&i]() -> adc_result_t<int> { return i; },
         [&i](int ii) -> adc_error_t {
             i = ii;
             return AdcDeviceErrorCode::ERROR_OK;
-        });
+        },
+        std::tuple<double, long>{});
 
     adc_result_t<int> ri = dev["1"];
     if (ri) {
         std::println("dev[1] = {}", ri.value());
+    } else {
+        std::println("cannot get dev[1] as int: {}", ri.error().message());
+    }
+
+    auto err = dev["1"] = 77;
+    if (err) {
+        std::println("cannot set dev[1] as int: {}", err.message());
+    }
+
+    adc_result_t<double> rd = dev["1"];
+    if (rd) {
+        std::println("dev[1] = {}", rd.value());
+    } else {
+        std::println("cannot get dev[1] as double: {}", rd.error().message());
     }
 
     return 0;