C++ FRUG #39 - The Two Wise Men

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Thirty ninth meeting of the C++ French User Group(C++FRUG) Paris.

💂 This Meetup is in English 🇬🇧

This meetup is hosted by Murex. Invitations are free, but we have a limited number of seats.
If you registered but cannot attend, please unregister so that somebody else can come.

Wednesday 11 December 2019

• 19h00 Welcoming

• 19h15 C++ News and host introduction

• 19h30 Lightning talks

• 20h00 Pizza

• 20h30 The Dawn of a New Error - Phil Nash

• 21h30 Type punning in modern C++ - Timur Doumler

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How to come

MUREX is a few meters away from the Trocadéro.

From the métro Trocadéro (ligne 6 & 9), take exit #6 (Musée de l'homme) and continue toward Avenue Paul Doumer. Turn left in Rue Vineuse (just after the Benjamin Franklin statue). MUREX is at number 45 in the Rue Vineuse.

From métro Passy, walk uphill until the roundabout, then take Rue Vineuse.

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Our Host

MUREX is a mondial leader in software development for capital markets. Everyday, throughout the world, prestigious financial institutions, hedge funds, asset managers and big companies rely on the collaborators and MUREX platform to support their market activities. The motto “pioneering again” sums-up its history: since its creation, MUREX continuously adapts to capital markets evolution by offering novel solutions adapted to the customers needs.

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Lightning talks

As an appetizer before the main talks, we'll have a lightning talks session. No reservation is needed. Anybody can participate if they have a talk or any kind of presentation (as long as it is relevant to the Meetup) that can be presented in less than 10 minutes (Q&A included).

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The Dawn of a New Error - Phil Nash

As a community we've tried many different ways to express, propagate and handle error conditions in our code over the years. Each seem to have different trade-offs, with none being perfect in all cases.

This presentation is the follow-up to my earlier talk, "Option(al) Is Not a Failure", where I surveyed existing error-handling approaches and score them against each other, leading up to the new proposal, p0709, "Zero-overhead deterministic exceptions".

We'll summarise some of that background so we're all on the same page, but in this talk we're going to dig into the proposal in more depth - and look at the supporting proposals, p1028 (std::error) and p1029 ([[move relocates]]) and others. We'll also comment similar mechanisms in other languages, notably Swift, to get an idea of how it might work out in practice.

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Type punning in modern C++ - Timur Doumler

Type punning is often used in C++ for fast floating-point math, deserialising C++ objects from a sequence of bytes, and other purposes. Popular techniques involve unions, reinterpret_cast, and memcpy. C++20 provides new useful tools, such as bit_cast. And there are proposals to provide even better control over C++ object creation in the future.

This talk is a comprehensive overview of all of these techniques. We will discuss when and how they can be used safely without causing undefined behaviour, what C++ does and does not allow you to do (and why), existing holes in the C++ language, and how to fix them. In the process, we will cover important C++ concepts such as object lifetime, value representations, and aliasing rules.