prohibit backends from changing our data

main/measured.cpp

@@ -19,7 +19,7 @@ typedef struct {
 } sensor_config_t;
 
 static std::vector<sensor_config_t> sensors;
-static qthing::measured::backend_t sens_backend = [](std::vector<qthing::measured::sensor_data_t>& data) {
+static qthing::measured::backend_t sens_backend = [](const std::vector<qthing::measured::sensor_data_t>& data) {
     for (auto const& d: data) {
         ESP_LOGI("measured", "name=%s type=%s unit=%s value=%f", d.name->c_str(), d.type->c_str(), d.unit->c_str(), d.value);
     }
@@ -77,7 +77,7 @@ void qthing::measured::registerSensor(std::string name, std::string type, std::s
 void qthing::measured::registerBackend(qthing::measured::backend_t new_backend) {
     qthing::measured::backend_t old_backend = sens_backend;
     
-    sens_backend = [old_backend, new_backend](std::vector<qthing::measured::sensor_data_t>& data) {
+    sens_backend = [old_backend, new_backend](const std::vector<qthing::measured::sensor_data_t>& data) {
         old_backend(data);
         new_backend(data);
     };
@@ -85,7 +85,7 @@ void qthing::measured::registerBackend(qthing::measured::backend_t new_backend)
     start_measured();
 }
 
-void qthing::measured::backend::mqtt(std::vector<qthing::measured::sensor_data_t>& data) {
+void qthing::measured::backend::mqtt(const std::vector<qthing::measured::sensor_data_t>& data) {
     if (is_mqtt_connected()) {
         for (auto const& d: data) {
             char message[16];

main/measured.h

@@ -23,13 +23,13 @@ namespace qthing {
         } sensor_data_t;
 
         typedef std::function<float()> sensor_t;
-        typedef std::function<void(std::vector<sensor_data_t>&)> backend_t;
+        typedef std::function<void(const std::vector<sensor_data_t>&)> backend_t;
 
         void registerBackend(backend_t new_backend);
         void registerSensor(std::string name, std::string type, std::string unit, sensor_t sensor);
 
         namespace backend {
-            void mqtt(std::vector<qthing::measured::sensor_data_t>& data);
+            void mqtt(const std::vector<qthing::measured::sensor_data_t>& data);
         }
     }
 }
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