CppCon 2017: Ben Deane & Jason Turner “constexpr ALL the Things!”

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constexpr: in C++11, a curiosity; in C++14, viable for more uses; now with added power, in C++17 will it become an important tool in the programmer's toolkit?

In this talk we will examine the possibilities and power of constexpr and explore what can (and what should) be done at compile-time with C++17. We'll present techniques for building constexpr data structures and algorithms, and look at what the standard provides and where it can improve. We'll also explore constexpr use of user defined literals for expressive compile-time abstractions.

Compile-time computation offers perhaps the ultimate zero-cost abstraction, and this talk attempts to gauge the power available with C++17 constexpr.
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Ben Deane: Principal Software Engineer, Blizzard Entertainment

Jason Turner: Developer, Trainer, Speaker

I'm available for contracting and onsite training.
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[henke]

"There was a misunderstanding between me and the compiler".

[jankodedic]

Great talk by Ben and JSON, as always!

[dipi]

Just when I thought I had a grip on C++ … well done, guys. ((slow-clap))

[arthur.passos]

"Jason" just talked about how we actually represent "Jason" values

[connorhorman]

I’ve done all of SHA2 in constexpr, and I’ve even written a program that Randomly decides when it wants to compile.

[cc.jsullivan]

wow, this really is constexpr all the things

[prezadent]

Great talk by Bean and Freddie, as is the norm.
I don't know whats going on either. I just try to fit in.

[JosefdeJoanelli]

"constexpra" tripped me up every time

[hanneshauptmann]

great talk by deane and jason, as always !

[OperationDarkside]

"You can clearly see..." -> No I can not, lol
Nonetheless, awesome

[xamidi]

The code on slide 20 (at 12:20) is not part of the github project and doesn't seem to compile.. Nothing of cx_map.h seems to be used in the project. When I comment all its content out and remove its import into cx_json_value.h, the project still compiles?! Whenever I try to use cx::map, it gives an error "no type named 'type' in 'struct std::enable_if<false, int>'". (Tried with GCC 7.2.0 as they claimed to use - concrete distribution: MinGW-w64

[alcesmir]

33:45 Isn't that essentially zipWith in haskell?

[outsiderst]

Wtf are those comments on every vid ;o

[connorhorman]

Next stop, Lua constexpr implementation.

[intvnut]

Did anyone else catch The Prisoner reference at 51:38?

[nmmm]

bit disappointing to see old Jason video in new clothes. Where I can see the source code of this?

[robbie_]

OK, this is just a fun thing to do isn't it (and interesting), but totally impractical. Would be faster/better to write a simple console app to parse json into a C++ structure, running it as a pre-build step.

[Runoratsu]

It's very impressive, but honestly? a) You can't debug it properly, really, and thus it's VERY hard to use in an environment with multiple people having to be able to read and understand the code, and b) as soon as your code base grows past a few 100k loc this "bit of compile time overhead" will drive everyone insane (if we assume a relatively constant percentage of constexpr code to runtime code). It's nice to speed up your runtime side, but if every recompile takes (literally!) hours, you can't work on the code base productively anymore.

[simgesonmez]

It's out of topic but why always guys??
I want to see more women on the stage any more especially in this discipline.

By the way, congrats guys, great talk :)