6 ms·

Just another self-promotion blog post with near zero information density. "Behold, the vastness of our vanity, regurgitating old news like we just discovered so

by juunpp 2y ago

Just another self-promotion blog post with near zero information density. "Behold, the vastness of our vanity, regurgitating old news like we just discovered something new." Do these posts really help with hiring? CLION also highlights unused includes, nothing new here. Use a good IDE. A networked ccache also does wonders if your org allows it. Slow build otherwise stem from a combination of: a) lack of proper modules in C++ (until recently) and b) unidiomatic or just terrible code bases. To help with the latter, hide physical implementations (PIMPL for class state, forward declarations for imports), avoid OOP-style C++ above all, minimize use of templates, design sound and minimal modules. No rocket science.

MathMonkeyMan 2y ago
Three times I've joined a team that has a substantial C++ codebase, and three times I've been tempted to use libclang based tooling to automate changes, or at least to identify patterns that could be changed. This article, while not the nerdy deep dive I'd like, does touch on what happens when you try to do that. You realize that the C++ standard library is really complicated, that your existing code is really fucked up, and that libclang is too limited a tool. You end up writing a XSLT engine in hacked up python, but by a different name. [LibTooling][1] is probably The Right Thing ("in C++", as the article says), but I never spent the time to get it working. Somebody write a DSL for C++ inspection and transformations that uses LibTooling as a backend. I bet there are many, but none close at hand. edit: [this][2] is close... [1]: https://clang.llvm.org/docs/LibTooling.html https://clang.llvm.org/docs/LibTooling.html [2]: https://clang.llvm.org/docs/LibASTMatchersTutorial.html#intermezzo-learn-ast-matcher-basics https://clang.llvm.org/docs/LibASTMatchersTutorial.html#inte...
stefan_ 2y ago
Is there anyone else that gets unreasonably angry at stuff like PIMPL? It is truly the most braindead, bereft of sense activity in this world. There was a comment in one of the many Rust threads that called C++ a respectable language now but then things like PIMPL snap you right back into the wasteland it is.
- wakawaka28 2y ago
  PIMPL is an elegant solution to multiple problems. Idk what you could possibly have against it besides the extra work involved. I don't think any language has solved the fundamental problem of hiding details better than PIMPL does.
  - bananaboy 2y ago
    I really like C#'s `partial` keyword as a solution to the problem of hiding implementation details. It lets you declare a class over several files, so you can have one file which is only the public interface, and another which has private implementation.
    - wakawaka28 2y ago
      That is essentially the same idea as PIMPL. You put the private parts of the class (e.g., the data layout) in some file that is held privately. I guess you could argue that there is extra syntax involved with PIMPL because C++ is more low-level than C#, but it's not so bad. The actual implementation of a class can be spread over as many files as you want in C++.
      - comex 2y ago
        And yet C, an even lower-level language, achieves the same effect without the duplication of PIMPL. You just forward-declare a struct, and declare functions that accept pointers to it: the header doesn't need to contain the struct fields, and you don't need to define any wrapper functions. Technically you can do the same in C++. But in C++ to make an idiomatic API you need methods instead of free functions, and you can't declare methods on forward-declared classes. Why not? Well, I can imagine some reasons… but they have more to do with C++'s idiosyncrasies than any fundamental limitation of a low-level language. The C++ committee could address this, but instead they seem to want to pretend separate compilation doesn't exist. (Why are there no official headers to forward-declare STL types, except for whatever happens to be in <iosfwd>?) Then they complain about how annoying it is to preserve ABI stability for the standard library, blaming the very concept of a stable ABI [1] [2], all while there are simple language tweaks that could make it infinitely more tractable! But now I'm ranting. [1] https://cor3ntin.github.io/posts/abi/ https://cor3ntin.github.io/posts/abi/ [2] https://thephd.dev/binary-banshees-digital-demons-abi-c-c++-help-me-god-please https://thephd.dev/binary-banshees-digital-demons-abi-c-c++-...

by juunpp 2y ago

MathMonkeyMan 2y ago

Three times I've joined a team that has a substantial C++ codebase, and three times I've been tempted to use libclang based tooling to automate changes, or at least to identify patterns that could be changed. This article, while not the nerdy deep dive I'd like, does touch on what happens when you try to do that. You realize that the C++ standard library is really complicated, that your existing code is really fucked up, and that libclang is too limited a tool. You end up writing a XSLT engine in hacked up python, but by a different name. [LibTooling][1] is probably The Right Thing ("in C++", as the article says), but I never spent the time to get it working. Somebody write a DSL for C++ inspection and transformations that uses LibTooling as a backend. I bet there are many, but none close at hand. edit: [this][2] is close... [1]: https://clang.llvm.org/docs/LibTooling.html https://clang.llvm.org/docs/LibTooling.html [2]: https://clang.llvm.org/docs/LibASTMatchersTutorial.html#intermezzo-learn-ast-matcher-basics https://clang.llvm.org/docs/LibASTMatchersTutorial.html#inte...

stefan_ 2y ago

Is there anyone else that gets unreasonably angry at stuff like PIMPL? It is truly the most braindead, bereft of sense activity in this world. There was a comment in one of the many Rust threads that called C++ a respectable language now but then things like PIMPL snap you right back into the wasteland it is.

wakawaka28 2y ago
PIMPL is an elegant solution to multiple problems. Idk what you could possibly have against it besides the extra work involved. I don't think any language has solved the fundamental problem of hiding details better than PIMPL does.
- bananaboy 2y ago
  I really like C#'s `partial` keyword as a solution to the problem of hiding implementation details. It lets you declare a class over several files, so you can have one file which is only the public interface, and another which has private implementation.
  - wakawaka28 2y ago
    That is essentially the same idea as PIMPL. You put the private parts of the class (e.g., the data layout) in some file that is held privately. I guess you could argue that there is extra syntax involved with PIMPL because C++ is more low-level than C#, but it's not so bad. The actual implementation of a class can be spread over as many files as you want in C++.
    - comex 2y ago
      And yet C, an even lower-level language, achieves the same effect without the duplication of PIMPL. You just forward-declare a struct, and declare functions that accept pointers to it: the header doesn't need to contain the struct fields, and you don't need to define any wrapper functions. Technically you can do the same in C++. But in C++ to make an idiomatic API you need methods instead of free functions, and you can't declare methods on forward-declared classes. Why not? Well, I can imagine some reasons… but they have more to do with C++'s idiosyncrasies than any fundamental limitation of a low-level language. The C++ committee could address this, but instead they seem to want to pretend separate compilation doesn't exist. (Why are there no official headers to forward-declare STL types, except for whatever happens to be in <iosfwd>?) Then they complain about how annoying it is to preserve ABI stability for the standard library, blaming the very concept of a stable ABI [1] [2], all while there are simple language tweaks that could make it infinitely more tractable! But now I'm ranting. [1] https://cor3ntin.github.io/posts/abi/ https://cor3ntin.github.io/posts/abi/ [2] https://thephd.dev/binary-banshees-digital-demons-abi-c-c++-help-me-god-please https://thephd.dev/binary-banshees-digital-demons-abi-c-c++-...