To me it sounds like someone messed up merging the previous standard with the new one. Previously the standard said this: (C++14 N4140, 7.1.6.4.7 [dcl.spec.auto]): When a […] return statement occurs in a function declared with a return type that contains a placeholder type, the deduced return type or variable type is determined from the … Read more
Using a hyperlinked C++ grammar, the parsing of decltype(void()) is: decltype( expression ) decltype( assignment-expression ) decltype( conditional-expression ) … lots of steps involving order of operations go here … decltype( postfix-expression ) decltype( simple-type-specifier ( expression-listopt ) ) decltype( void() ) So void() is a kind of expression here, in particular a postfix-expression. Specifically, … Read more
No need to cast from or to a pointer to void in C: 6.3.2.3 Pointers 1 A pointer to void may be converted to or from a pointer to any incomplete or object type. A pointer to any incomplete or object type may be converted to a pointer to void and back again; the result … Read more
The JUnit FAQ has a section on testing methods that return void. In your case, you want to test a side effect of the method called. The example given in the FAQ tests that the size of a Collection changes after an item is added. @Test public void testCollectionAdd() { Collection collection = new ArrayList(); … Read more
To summarize from other answers & comments, basically you have 3 choices: Get C++17 to be able to use [[nodiscard]] In g++ (also clang++), use compiler extensions like __wur (defined as __attribute__ ((__warn_unused_result__))), or the more portable (C++11 and up only) [[gnu::warn_unused_result]] attribute. Use runtime checks to catch the problem during unit testing If all … Read more
Maybe yield a Consumer of Event, so you yield something useful, the trade off is one more line for consumer.accept. Consumer<Event> consumer = switch (event.getEventType()) { case ORDER -> e -> handle((OrderEvent) e); case INVOICE -> e -> handle((InvoiceEvent) e); case PAYMENT -> e -> handle((PaymentEvent) e); }; consumer.accept(event); Continue if you concern performance Based … Read more
Because it’s simply the way the language is defined. A method can use return statements to return control to its caller. In a method returning void, return statements cannot specify an expression. In a method returning non-void, return statements must include an expression that computes the return value. It’s an arbitrary decision (presumably made for … Read more
Yes, you can return from a void function. Interestingly, you can also return void from a void function. For example: void foo() { return void(); } As expected, this is the same as a plain return;. It may seem esoteric, but the reason is for template consistency: template<class T> T default_value() { return T(); } … Read more
You should avoid async void. Only use async void for event handlers. DelegateCommand is (logically) an event handler, so you can do it like this: // Use [InternalsVisibleTo] to share internal methods with the unit test project. internal async Task DoLookupCommandImpl(long idToLookUp) { IOrder order = await orderService.LookUpIdAsync(idToLookUp); // Close the search IsSearchShowing = false; … Read more
const void is a type which you can form a pointer to. It’s similar to a normal void pointer, but conversions work differently. For example, a const int* cannot be implicitly converted to a void*, but it can be implicitly converted to a const void*. Likewise, if you have a const void* you cannot static_cast … Read more