hpx | The C++ Standard Library for Parallelism and Concurrency | Architecture library

I want to compile a simple test project for a library that makes use of a ftd2xx driver. I already compiled it successfully on linux and I'm trying to do the same on Windows. The main difference are some minor modification to the library.

The test file I want to compile is this:

I have app that I want to retreive data which are messages represented in uid document from Firestore database as explained here and these messages stored like so : ChatRoom->chatRoomId->chat-> uid-> messages

but I receive this error :

The following NoSuchMethodError was thrown building StreamBuilder(dirty, state: _StreamBuilderBaseState#56cb5): Class 'QuerySnapshot' has no instance getter 'document'. Receiver: Instance of 'QuerySnapshot' Tried calling: document

The relevant error-causing widget was: StreamBuilder file:///Users/ahmedhussain/Downloads/khamsat/Client%20Apps/HPX-KSA/hpx_ksa/lib/Screens/messages.dart:21:12 When the exception was thrown, this was the stack: #0 Object.noSuchMethod (dart:core-patch/object_patch.dart:53:5) #1 _MessagesState.chatRoomList. (package:hpxksa/Screens/messages.dart:25:38)

Here is my code:

I am using HERE api to get information about geographic points. In my request I ask for multiple layers and for all of them I get information, expect for most of my points when I try to read the LINK_ATTRIBUTE2 layer, it says it is undefined:

I have HTML files and I want to know how I can know the width of them Dynamically. I am trying to convert HTML to PDF using Flying Saucer. I am using Jsoup to add width with CSS

@page( size: wpx hpx;)

I want wpx to be dynamic depending on HTML width.

I've tried to use transform_reduce from hpx as given in the Answer https://stackoverflow.com/a/54481320/11008404 but I can't compile it. My code so far:

I have the following data frame:

In MATLAB, I have a block of text that I need to split apart. This is an example of such text:

In HPX introduction tutorials you learn that you can make use of future's then() method, that allows you to enqueue some operation to be computed when the future is ready.

In this manual there is a sentence that says "Used to build up dataflow DAGs (directed acyclic graphs)" when explaining how to use thens.

My question is, what does it mean that this queue has to be acyclic? Can I make a function that re-computes a future inside a then? This would look like myfuture.then( recompute myfuture ; myfuture.then() ) ?

cppreference documentation https://en.cppreference.com/w/cpp/algorithm/for_each says that:

• If execution of a function invoked as part of the algorithm throws an exception and ExecutionPolicy is one of the three standard policies, std::terminate is called. For any other ExecutionPolicy, the behavior is implementation-defined.

I interpret that this means that I cannot, out-of-the-box, throw from the for_each passed function and expect to catch the excetion or some information related to it.

The reason I was expecting to use exceptions was so that I could partially undo (revert) the changes made in the for_each call. (Maybe there is a better algorithm for that).

However, just by chance I found a historical version of for_each which is documented to have a different, more interesting behavior:

http://man.hubwiz.com/docset/C.docset/Contents/Resources/Documents/output/en/cpp/algorithm/for_each.html

• if policy is std::parallel_vector_execution_policy, std::terminate is called
• if policy is std::sequential_execution_policy or std::parallel_execution_policy, the algorithm exits with an std::exception_list containing all uncaught exceptions. If there was only one uncaught exception, the algorithm may rethrow it without wrapping in std::exception_list. It is unspecified how much work the algorithm will perform before returning after the first exception was encountered.

Which seems to imply that instead of terminateing, there is the possibility of actually using exceptions.

So, why std::exception_list was eliminated?, was it too controversial, too complicated, too (memory) costly?

Even if I agree with the logic, I really don't have any other option because parallel for_each returns void (instead of the UnaryFunction back, which is also surprising). Therefore, this std::exception_list protocol seem to me in a necessary component to undo a failed-to-complete for_each instruction.

Is it reasonable to expect that some new custom policy, e.g. par_with_failed_list will appear somewhere allowing for undoing.

More context: This pattern of undoing a failed loop is used in construction of containers. I want to implement a custom (parallel/sequencial) uninitialized_value_construct_n which "undo's" (destroy) the initilized objects when (any of the unsequenced) constructions fail.

EDIT1: On a second though, it might be possible to pass a captured variable in the lambda to a function parameter. This variable could be a shared concurrent data that can store the exceptions as they happen (as a exception_list). I wonder if this has been done already.

EDIT2: I found an implementation of exception_list in HPX,
https://github.com/STEllAR-GROUP/hpx/blob/master/hpx/exception_list.hpp
https://github.com/STEllAR-GROUP/hpx/blob/master/src/exception_list.cpp