Merge pull request arximboldi#164 from jarzec/throw-on-uninitialized

Throw on access to uninitialized reader/writer

lager/detail/access.hpp

@@ -39,7 +39,7 @@ class access
     }
 
     /*!
-     * Returns a pointer to th underlying node of an object, if
+     * Returns a pointer to the underlying node of an object, if
      * exists.
      */
     template <typename T>
@@ -49,7 +49,7 @@ class access
     }
 
     /*!
-     * Returns a a optional boost.signal to the specific watchers of
+     * Returns an optional boost.signal to the specific watchers of
      * the underlying signal of an object.
      */
     template <typename T>

lager/reader.hpp

@@ -71,7 +71,10 @@ struct reader_mixin
 
     auto node_() const
     {
-        return detail::access::node(*static_cast<const DerivT*>(this));
+        if(auto node = detail::access::node(*static_cast<const DerivT*>(this))) {
+            return node;
+        }
+        throw std::runtime_error("Accessing uninitialized reader");
     }
 };
 

lager/writer.hpp

@@ -70,7 +70,10 @@ struct writer_mixin
 
     auto node_() const
     {
-        return detail::access::node(*static_cast<const DerivT*>(this));
+        if(auto node = detail::access::node(*static_cast<const DerivT*>(this))) {
+            return node;
+        }
+        throw std::runtime_error("Accessing uninitialized writer");
     }
 };
 

test/cursor.cpp

@@ -34,20 +34,29 @@ using namespace lager;
 TEST_CASE("in, construction and assignment from temporary")
 {
     reader<int> in1;
+    // Access to uninitialized reader should throw an exception
+    REQUIRE_THROWS(in1.get());
     in1 = make_state(0);
     reader<int> in2{make_state(0)};
 }
 
 TEST_CASE("out, construction_and_assignment_from_temporary")
 {
     writer<int> out1;
+    // Access to uninitialized writer should throw an exception
+    REQUIRE_THROWS(out1.set(42));
+    REQUIRE_THROWS(out1.update([](auto){ return 42;}));
     out1 = make_state(0);
     writer<int> out2{make_state(0)};
 }
 
 TEST_CASE("inout, construction_and_assignment_from_temporary")
 {
     cursor<int> inout1;
+    // Access to uninitialized cursor should throw an exception
+    REQUIRE_THROWS(inout1.get());
+    REQUIRE_THROWS(inout1.set(42));
+    REQUIRE_THROWS(inout1.update([](auto){ return 42;}));
     inout1 = make_state(0);
     cursor<int> inout2{make_state(0)};
 }