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I don't write C++ for a living, and only have ~2 years' experience writing it for some hobby projects on weekends. I've found that the way I'm most productive

I don't write C++ for a living, and only have ~2 years' experience writing it for some hobby projects on weekends. I've found that the way I'm most productive is by using data-oriented design where I put everything in structs and don't use classes. I still use a lot of modern C++ library features, but it reads more like C. For example: struct BufferPool { alignas(PAGE_SIZE) char frames[BUF_POOL_NUM_FRAMES][PAGE_SIZE]; std::atomic_uint32_t free_frames[BUF_POOL_NUM_FRAMES]; std::atomic_uint32_t pin_count[BUF_POOL_NUM_FRAMES]; std::atomic_bool is_dirty[BUF_POOL_NUM_FRAMES]; std::atomic_uint32_t page_id_to_frame_idx[]; }; std::span<const char> BufferPool_get_record(BufferPool* pool, RecordID rid, int db_file_fd); What's nice about having all this stuff thrown into the language is that you're free to pick and choose what you want to adopt from it. For a long time, I tried to cram everything I wrote in C++ into an OOP pattern with classes, and it just didn't jive with me. Then I stopped doing that and started writing it more like TypeScript/Kotlin/C which I'm more familiar with and it's been a lot more pleasant ever since. There's been so much great stuff in C++ 17/20/23 and you can just cherry pick all the bits you want to use out of it and ignore the rest.

dagmx 4y ago
FWIW, structs and classes are largely identical in C++ , with the exception of public/private defaults. So using one over the other doesn’t really change anything with regards to data oriented design.
- gavinray 4y ago
  Aye, as opposed to D where structs are value types and classes are reference types It's just a small annoyance to have to put "public:" at the top of every data-class definition So I use structs everywhere but you're completely right, no real difference
  - dagmx 4y ago
    Yeah I do the same as you since I write a ton of Swift (which does the same delineation as D). It’s mostly just a mental marker for myself that I want to treat one as a value type.
cbsmith 4y ago
I mean, if you change the name to "BufferPool::get_record" and you use an implicit this pointer instead of your "pool" argument, you have a method. It seems like you're fighting the paradigm more than you need to.
- gavinray 4y ago
  You're not wrong but for some reason this style is easier for me to work with I know logically/semantically they're equivalent. The v-table function generated if the method is moved inside the class/struct winds up being identical. Dunno what it is, some kind of familiarity bias with the way the code is laid out I guess, not coming from OOP languages
  - thelopa 4y ago
    Note: it wouldn’t generate a vtable entry unless the method was declared virtual.
    - gavinray 4y ago
      Ahh, what do you call the method table thing for non-virtual classes?
      - cornstalks 4y ago
        There is no table if no ‘virtual’ is involved.
        adrian_b 4y ago
        To be more clear, when no "virtual" method is declared, then no table is generated because none is needed. In this case, the addresses of all the methods are known at compile time and the compiler knows which to choose when anyone is invoked in the source code, based on the type of the object and on the types of the method arguments. When there is at least one "virtual" method and you have a pointer to an object, the type of the object cannot be known at compile-time, so the compiler cannot determine which method to invoke. That is why the compiler needs to create a table with pointers to the virtual methods for each class with such methods, and each object of those classes must include a pointer to the corresponding vtable, so that the correct method to invoke can be determined at run time (from the index of the virtual method).
midnightclubbed 4y ago
If I was code reviewing this I would strongly suggest std::array instead of those raw array;) I’m also curious why you have page_id_to_frame_idx[] without a size. If you are using that paradigm to read off the end of the struct then it needs commenting heavily, if it’s a typo then std::array would have caught it. I do understand that it’s just a snippet of code to show a style, so ignore this pedant!

dagmx 4y ago

FWIW, structs and classes are largely identical in C++ , with the exception of public/private defaults. So using one over the other doesn’t really change anything with regards to data oriented design.

gavinray 4y ago
Aye, as opposed to D where structs are value types and classes are reference types It's just a small annoyance to have to put "public:" at the top of every data-class definition So I use structs everywhere but you're completely right, no real difference
- dagmx 4y ago
  Yeah I do the same as you since I write a ton of Swift (which does the same delineation as D). It’s mostly just a mental marker for myself that I want to treat one as a value type.

cbsmith 4y ago

I mean, if you change the name to "BufferPool::get_record" and you use an implicit this pointer instead of your "pool" argument, you have a method. It seems like you're fighting the paradigm more than you need to.

gavinray 4y ago
You're not wrong but for some reason this style is easier for me to work with I know logically/semantically they're equivalent. The v-table function generated if the method is moved inside the class/struct winds up being identical. Dunno what it is, some kind of familiarity bias with the way the code is laid out I guess, not coming from OOP languages
- thelopa 4y ago
  Note: it wouldn’t generate a vtable entry unless the method was declared virtual.
  - gavinray 4y ago
    Ahh, what do you call the method table thing for non-virtual classes?
    - cornstalks 4y ago
      There is no table if no ‘virtual’ is involved.
      - adrian_b 4y ago
        To be more clear, when no "virtual" method is declared, then no table is generated because none is needed. In this case, the addresses of all the methods are known at compile time and the compiler knows which to choose when anyone is invoked in the source code, based on the type of the object and on the types of the method arguments. When there is at least one "virtual" method and you have a pointer to an object, the type of the object cannot be known at compile-time, so the compiler cannot determine which method to invoke. That is why the compiler needs to create a table with pointers to the virtual methods for each class with such methods, and each object of those classes must include a pointer to the corresponding vtable, so that the correct method to invoke can be determined at run time (from the index of the virtual method).

midnightclubbed 4y ago

If I was code reviewing this I would strongly suggest std::array instead of those raw array;) I’m also curious why you have page_id_to_frame_idx[] without a size. If you are using that paradigm to read off the end of the struct then it needs commenting heavily, if it’s a typo then std::array would have caught it. I do understand that it’s just a snippet of code to show a style, so ignore this pedant!