5 ms·

Could you please explain more about the process you're using? Are you compiling external dependencies as an integral part of building your own code?

derefr 7y ago
They’re using some header-only libraries, presumably. Which, after all, is one of the only unique benefits of C++ that would lead you to choose it for a green-field project over, say, Rust. Header-only template libs + link-time WPO = inlining of template-instantiated monomorphized methods to their type-strict callers. This is the feature that leads e.g. LLVM to be written in C++.
- steveklabnik 7y ago
  Rust doesn’t have headers, but can still do this.
CreRecombinase 7y ago
Anything in your headers is (more or less equivalent to being) copy-pasted into your own code. Many dependencies are header-only (which is the only option I'm aware of if the code is templated).
petters 7y ago
This is the only sane way of using C++. All C++ dependencies in the same repo, because there is no standard C++ ABI. I am compiling my C++ codebase with gcc, clang, emscripten to wasm, visual studio. Impossible if all dependencies are not present in a "third-party" folder. Google's Abseil library is intended to be used this way. Otherwise, use the C ABI between dependencies.
- gpderetta 7y ago
  > standard C++ ABI. All major OS have a standard, very stable C++ ABI. Some of them also guarantee a stable ABI for the library components. Of course you cannot use a library built for, say, Windows on Linux but that's true for all languages.
  - jdsully 7y ago
    For windows that is a very recent change. The ABI used to change with every compiler rev. Further without buyin from the actual standard there’s no gurantee a breaking change won’t be forced by the standard at some point.
    - pjmlp 7y ago
      Not for libraries exposed as DLL or COM. Although one might argue that is only a C++ subset.
      - jdsully 7y ago
        COM is based off of the C ABI not C++. This was done specifically because C++ does not have a stable ABI.
        pjmlp 7y ago
        There is no such thing as C ABI, rather Windows ABI, which you can even select several calling conventions, including Pascal based one. COM is based on the way Visual C++ lays out the VMT, and only masochists use it from bare bones C.
        int_19h 7y ago
        C ABI is basically structs + functions + function pointers. On Win32, functions and function pointers includes calling conventions, but that's not really important. COM is a C ABI in a sense that its spec defines everything in these terms. Yes, in practice it translates nicely to C++ vtables, but the stability guarantees are defined on the lower level.
        pjmlp 7y ago
        From that point of view, it is also a Pascal ABI.

derefr 7y ago

They’re using some header-only libraries, presumably. Which, after all, is one of the only unique benefits of C++ that would lead you to choose it for a green-field project over, say, Rust. Header-only template libs + link-time WPO = inlining of template-instantiated monomorphized methods to their type-strict callers. This is the feature that leads e.g. LLVM to be written in C++.

steveklabnik 7y ago
Rust doesn’t have headers, but can still do this.

CreRecombinase 7y ago

Anything in your headers is (more or less equivalent to being) copy-pasted into your own code. Many dependencies are header-only (which is the only option I'm aware of if the code is templated).

petters 7y ago

This is the only sane way of using C++. All C++ dependencies in the same repo, because there is no standard C++ ABI. I am compiling my C++ codebase with gcc, clang, emscripten to wasm, visual studio. Impossible if all dependencies are not present in a "third-party" folder. Google's Abseil library is intended to be used this way. Otherwise, use the C ABI between dependencies.

gpderetta 7y ago
> standard C++ ABI. All major OS have a standard, very stable C++ ABI. Some of them also guarantee a stable ABI for the library components. Of course you cannot use a library built for, say, Windows on Linux but that's true for all languages.
- jdsully 7y ago
  For windows that is a very recent change. The ABI used to change with every compiler rev. Further without buyin from the actual standard there’s no gurantee a breaking change won’t be forced by the standard at some point.
  - pjmlp 7y ago
    Not for libraries exposed as DLL or COM. Although one might argue that is only a C++ subset.
    - jdsully 7y ago
      COM is based off of the C ABI not C++. This was done specifically because C++ does not have a stable ABI.
      - pjmlp 7y ago
        There is no such thing as C ABI, rather Windows ABI, which you can even select several calling conventions, including Pascal based one. COM is based on the way Visual C++ lays out the VMT, and only masochists use it from bare bones C.
        int_19h 7y ago
        C ABI is basically structs + functions + function pointers. On Win32, functions and function pointers includes calling conventions, but that's not really important. COM is a C ABI in a sense that its spec defines everything in these terms. Yes, in practice it translates nicely to C++ vtables, but the stability guarantees are defined on the lower level.
        pjmlp 7y ago
        From that point of view, it is also a Pascal ABI.