[GitHub] [celix] pnoltes commented on a change in pull request #272: Feature/cpp17 promise

[GitBox <gi...@apache.org>]

pnoltes commented on a change in pull request #272:
URL: https://github.com/apache/celix/pull/272#discussion_r457653259



##########
File path: misc/experimental/promise/CMakeLists.txt
##########
@@ -52,7 +52,7 @@ if (PROMISE OR PROMISE_STANDALONE)
         $<INSTALL_INTERFACE:include/celix/promise>
     )
     target_link_libraries(Promise INTERFACE TBB::tbb Threads::Threads)
-    target_compile_options(Promise INTERFACE -frtti) #Note needed for TBB
+    target_compile_options(Promise INTERFACE -frtti -std=c++17) #Note needed for TBB

Review comment:
       Te note, is only for -frtti not c++17

##########
File path: misc/experimental/promise/api/celix/Deferred.h
##########
@@ -136,12 +139,81 @@ namespace celix {
          * the specified Promise. The returned Promise will be resolved with a failure of IllegalStateException if the
          * associated Promise was already resolved when the specified Promise was resolved.
          */
-        //TODO support void promises
-        //Promise<void> resolveWith(Promise<T> with);

Review comment:
       A Promise<void> can be used as way to see if something is done (ok or nok (onResolve on onFailure). 
   
   The use case for resolving a void promise with a typed promise is (IMO) if you are not interested in the result downstream, but use want to use the promise as a sync. 
   
   So for example you get Promise<double> from some function (maybe 3rd party) where the double is the time it took to process, but in "our" API we just want to indicate whether were a done (success or failed). In this case you can create a Promise<void> and resolve it with the Promise<double> (regardless if the Promise<double> is already resolved or not)




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