Fix lints in DataStorm demos (#228)

.clang-tidy

@@ -13,6 +13,7 @@ WarningsAsErrors:  '*'
 HeaderFilterRegex: ''
 UseColor: true
 FormatStyle: 'file'
+ExtraArgs: ['-std=c++17']
 CheckOptions:
   modernize-use-nullptr.NullMacros: 'NULL'
   # std::exception_ptr is a cheap to copy, pointer-like type; we pass it by value all the time.

cpp/DataStorm/clock/Writer.cpp

@@ -33,7 +33,7 @@ namespace DataStorm
         static chrono::system_clock::time_point decode(const Ice::ByteSeq&)
         {
             assert(false); // Not used by the reader but it still needs to be declared.
-            return chrono::system_clock::time_point();
+            return {};
         }
     };
 };

cpp/DataStorm/stock/Reader.cpp

@@ -44,16 +44,16 @@ main(int argc, char* argv[])
             // Get the set of stocks connected with the any reader and display their ticker.
             std::promise<void> p;
             stocks.onConnectedKeys(
-                [&p](vector<string> tickers)
+                [&p](const vector<string>& tickers)
                 {
                     cout << "Available stock(s): " << endl;
-                    for (auto ticker : tickers)
+                    for (const auto& ticker : tickers)
                     {
                         cout << ticker << endl;
                     }
                     p.set_value();
                 },
-                [](DataStorm::CallbackReason action, string ticker)
+                [](DataStorm::CallbackReason action, const string& ticker)
                 {
                     if (action == DataStorm::CallbackReason::Connect)
                     {
@@ -90,11 +90,11 @@ main(int argc, char* argv[])
         // Wait for the writer to be connected.
         reader->waitForWriters();
 
-        auto displaySample = [](DataStorm::Sample<string, Stock> s)
+        auto displaySample = [](const DataStorm::Sample<string, Stock>& s)
         {
             if (s.getEvent() == DataStorm::SampleEvent::Add || s.getEvent() == DataStorm::SampleEvent::Update)
             {
-                auto value = s.getValue();
+                const auto& value = s.getValue();
                 cout << "Stock: " << value.name << " (" << s.getKey() << ")" << endl;
                 cout << "Price: " << value.price << endl;
                 cout << "Best bid/ask: " << value.bestBid << '/' << value.bestAsk << endl;

cpp/DataStorm/stock/Writer.cpp

@@ -14,20 +14,19 @@ using namespace Demo;
 
 namespace
 {
-
-    std::random_device random;
-
     DataStorm::SingleKeyWriter<string, Stock>
-    makeStock(DataStorm::Topic<string, Stock>& topic, string ticker, Stock stock)
+    makeStock(DataStorm::Topic<string, Stock>& topic, const string& ticker, const Stock& stock)
     {
         // Create a stock writer for the given ticker and add the initial stock value.
-        auto writer = DataStorm::makeSingleKeyWriter(topic, std::move(ticker));
-        writer.add(std::move(stock));
+        auto writer = DataStorm::makeSingleKeyWriter(topic, ticker);
+        writer.add(stock);
         return writer;
     }
 
     void updateStock(DataStorm::SingleKeyWriter<string, Stock>& stock)
     {
+        static std::random_device random;
+
         // Send a partial update to either update the price or the volume with the given writer.
         if (uniform_int_distribution<int>(1, 10)(random) < 8)
         {
@@ -41,7 +40,6 @@ namespace
                 uniform_int_distribution<int>(volume * 95 / 100, volume * 105 / 100)(random));
         }
     }
-
 }
 
 int
@@ -140,7 +138,7 @@ main(int argc, char* argv[])
                 cout << "unknown stock `" << stockName << "'" << endl;
                 return 1;
             }
-            writers.push_back(makeStock(topic, std::move(stockName), stocks[stockName]));
+            writers.push_back(makeStock(topic, stockName, stocks[stockName]));
         }
 
         // Update the stock value or volume attributes.