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Overview: What are Cpp2 and cppfront? How do I get and build cppfront?

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Re: Overview: What are Cpp2 and cppfront? How do I get and build cppfront?

#11

Post by suby »

I spent the other day writing an archetype entity component system which made heavy use of template metaprogramming. I try to avoid this if possible, but it was an exercise in seeing how performant I could make it, and so I wanted to offload as much work as I could manage to compile time and avoid things like virtual dispatch. API similar to the basic parts of entt.

My take away from the exercise is that this is not a language for human beings. I was successful in writing it, but it was extremely difficult and frustrating. Part of the frustration is because conceptually what I wanted to accomplish was not difficult, but figuring out how to express it was a nightmare. I am not new to the language, I've been writing C++ since 2009, it was the first language I learned and I've spent nearly every day of my life since then writing at least some C++ code. Even so, I can't say that I truly understand this shit.

I'm hoping cpp2 brings us someplace closer to a language that mere mortals can understand. I don't want the next generation writing C++.

Re: Overview: What are Cpp2 and cppfront? How do I get and build cppfront?

#12

Post by loeg »

frankjr wrote: post #6
superamadeus wrote: post #5

Is there any discussion or in-depth explanation of the syntax choices? I understand that a goal was context free unambiguous parsing. But there are some things that surprise me. For example, string interpolation: "Hello, (msg)$!\n" Why “(msg)$” and not “$(msg)”? Surely the latter is easier to parse?

https://github.com/hsutter/cppfront/wiki/Design-note:-Captur...

Raises more questions honestly. This looks more different from today’s C++ than Rust.

Re: Overview: What are Cpp2 and cppfront? How do I get and build cppfront?

#14

Post by loeg »

ThouYS wrote: post #10
colonwqbang wrote: post #8

Most of my personal issues aren't with C++ syntax as such (although it also has many problems). My main gripes are: 1. Very slow compilation. 2. Poor encapsulation, adding private functions requires recompiling all dependents, see (1). 3. Comically huge symbols make debugging much harder than it needs to be -- today gdb OOM'd my 16GB laptop when trying to form a backtrace of a typical QT application coredump. Unfortu…

under what circumstances does (2) hold? for vanilla methods it's no problem

If you touch a header, even private only, includers will rebuild. Modules might fix this.

Re: Overview: What are Cpp2 and cppfront? How do I get and build cppfront?

#15

Post by phkahler »

ThouYS wrote: post #10
colonwqbang wrote: post #8

Most of my personal issues aren't with C++ syntax as such (although it also has many problems). My main gripes are: 1. Very slow compilation. 2. Poor encapsulation, adding private functions requires recompiling all dependents, see (1). 3. Comically huge symbols make debugging much harder than it needs to be -- today gdb OOM'd my 16GB laptop when trying to form a backtrace of a typical QT application coredump. Unfortu…

under what circumstances does (2) hold? for vanilla methods it's no problem

>>> 2. Poor encapsulation, adding private functions requires recompiling all dependents

>> under what circumstances does (2) hold?

To add a private member variable or function, you need to put it in the class definition in the header file. Then anything that includes the header needs to be recompiled.

Re: Overview: What are Cpp2 and cppfront? How do I get and build cppfront?

#16

Post by mort96 »

pciexpgpu wrote: post #9

I wonder how this compares with Carbon -> C++ [0]. Carbon is (was?) a fantastic proposal, but not sure if it has lost steam since it was introduced or how well it is being adopted (be it inside Google or outside)? Being able to incrementally/interchangeably use/call existing C++ code (and vice versa) seems like a great design choice (in Carbon) without having to introspect the actual generated code. Not sure how easy…

Carbon isn't "being adopted", it's still being developed. Making a programming language takes time. Let them at least get to a point where they release some form of public beta (i.e a few more years, at least) before talking about adoption.

Re: Overview: What are Cpp2 and cppfront? How do I get and build cppfront?

#18

Post by colonwqbang »

ThouYS wrote: post #10
colonwqbang wrote: post #8

Most of my personal issues aren't with C++ syntax as such (although it also has many problems). My main gripes are: 1. Very slow compilation. 2. Poor encapsulation, adding private functions requires recompiling all dependents, see (1). 3. Comically huge symbols make debugging much harder than it needs to be -- today gdb OOM'd my 16GB laptop when trying to form a backtrace of a typical QT application coredump. Unfortu…

under what circumstances does (2) hold? for vanilla methods it's no problem

C++ build systems are typically based on file timestamps. Modifying a header file triggers recompilation of all translation units including that header.

There are workarounds like pimpl (aka. C style encapsulation). But this requires extra boilerplate and indirection. C++ modules might fix it at some point, but after 35 years of not having them in C++ most real life codebases aren't set up that way and may never be.

Re: Overview: What are Cpp2 and cppfront? How do I get and build cppfront?

#20

Post by ThouYS »

phkahler wrote: post #15
ThouYS wrote: post #10

Earlier quoted context omitted.

under what circumstances does (2) hold? for vanilla methods it's no problem

>>> 2. Poor encapsulation, adding private functions requires recompiling all dependents >> under what circumstances does (2) hold? To add a private member variable or function, you need to put it in the class definition in the header file. Then anything that includes the header needs to be recompiled.

they don't need to be. dependents will continue functioning, because ABI hasn't changed
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