C++ World Café

At the C++ UG Karlsruhe on June 14th 2017


The C++ World Café discussion format helps to get a broad and current overview of some C++ topics, to get to know peer developers, and is a lot of fun. Our C++ World Café got support from four C++ gurus from around the world: Anthony Williams, Jason Turner, Robert Ramey, and Walter Bright. We investigated the following 4 questions:

Jason Turner How can I become a better C++ developer?

Skype session: Jason Turner

Table Host: Robert Schneider

Robert Ramey Which libraries/frameworks are most helpful for me, and why?

Skype session: Robert Ramey

Table Host: Ralf Mikulla

Walter Bright How does the compiler help/hinder me?

Skype session: Walter Bright

Table Host: Andreas Zwinkau

Anthony Williams Which features and advantages does C++ offer for parallelization?

Skype session: Anthony Williams

Table Host: Timo Bingmann


The C++ user group Karlsruhe organized a World Café at one of its last meetups, to have everyone in the group involved in discussions, and to get a broad overview of some C++ topics. In our World Café format, small groups of 4-6 people sit together at each table to discuss about a given question for 30 minutes, noting down their findings. This constitutes a round, with 4 rounds in total. All but each table's host switch tables each round, and the table host introduces the topic and previous findings to the new-comers. Each table discusses a different question. To have a satisfying event and help the table hosts, we set the following goals for our C++ Word Café: To make sure the goals are reached, we got support from the C++ gurus Anthony, Jason, Robert, and Walter (our "ask the expert" lifelines, so to speak): at the last round, each table started a Skype session with one of those gurus. They gave us feedback and answers to open questions, motivated everybody to engage in the discussion, and made the whole event really fun. To give you an impression, here are our results:

How can I become a better C++ developer?

In the first three rounds, we brainstormed about In the fourth and last round, Jason Turner joined in via Skype, and Further material:

Which libraries/frameworks are most helpful for me, and why?

In the first three rounds, different libraries and their use was discussed. The focus, however, was on problems when using libraries, covering the following four points:
  1. triangle between learning, enabling, and efficiency;
  2. documentation;
  3. managing dependencies;
  4. managing patches.
In the fourth and last round, Robert Ramey joined in via Skype, commented on the four points above and then went into detail about economics, responsibilities and testing:
  1. Getting a library right entails a lot more effort then first meets the eye. Hence many redo something already present, even though it is not economic.
  2. Weak documentation is a running festering sore in the whole software development community. Robert covers this in many of his presentations at CppCon.
  3. People have had unrealistic expectations about automatic dependency managers; you have to make the dependency related to your particular application.
Furthermore: Further material:

Which features and advantages does C++ offer for parallelization?

In all the first three rounds, as well as the last round together with Anthony Williams, we In the fourth and last round, Anthony Williams joined in via skype, and Further material:

How does the compiler help/hinder me?

In the first three rounds, the discussions covered warnings and error messages, meta programming, linking, assertions, code analysis, optimizations, undefined behavior, and buggy compilers. In the fourth and last round, Walter Bright joined in via skype, gave feedback to many previous discussed items and answered some new questions that came up, covering Further material:


Though a bit of work to prepare, our C++ World Café was a big success since we achieved all goals: We covered a vast amount of aspects for each question and had really fun discussions. A big thanks to Anthony, Jason, Robert, and Walter for their support, to Andreas, Ralf, Robert, and Timo for their moderation, and to Clausmark GmbH for their sponsoring. Also a big pardon for the technical difficulties we had, and thanks to Mark Edwards for post-processing the audio to improve the quality as much as possible. Which leads to our experience with and advice for the C++ World Café format: To achieve the aforementioned goals, do one in your user group or even at a conference, since it scales well with the number of participants! The general advice for World Cafés are quite accurate and helpful. They do focus preparation too much on finding good questions, I think, because that is rather easy for a C++ World Café. Further questions could be: The preparation of the tables was also simpler than you would expect from the World Café advice; just throw a paper table cloth (available cheaply in larger food or drug stores) over your tables to write on, and put some cookies on top. Rather put your energy into the preparation for the moderation and equipment: find your table hosts early on, not spontaneously at the meeting, since you need to find people who know about the respective topic, and to brief them about the C++ World Café format. If you include Skype sessions, you have all the challenges that audio and video recordings entail, multiplied by the number of tables: Each table must have Skype online and running. Running in a quiet environment, that is! While it is simple for a human ear to tune out the noise from the neighbor table, this is no longer possible once sound has been recorded through a laptop microphone, as you can unfortunately hear in some of our recordings. Sorry Jason and Robert, and thanks for handling it so well. My rule of thumb: at the very least, have 10 meters distance between each two tables. If you are recording the Skype sessions, experiment with the Sykpe or screen/audio recording tool well in advance, especially with how to avoid echos due to acoustic feedback loops. But with this advice, you only have to put in some preparation and get all the benefits described above. So, conduct a C++ World Café, and then let others know about your results!

cc byCopyright © 2017 Dr. David Faragó. This work, except for the pictures, is licensed under the Creative Commons Attribution 4.0 International License (CC BY 4.0).