3 ms·

Most people prefer the first over the second. But I think that Linus really should prefer the second over the first. Let me try to explain why. There is a we

by btilly 6y ago

Most people prefer the first over the second. But I think that Linus really should prefer the second over the first. Let me try to explain why. There is a well-known saying attributed to David Wheeler, "All problems in computer science can be solved by another level of indirection." Except the problem of having too many layers of indirection. Also both quotes are often seeing with "abstraction" instead of "indirection". There is a not well-known saying that you can attribute to me, "Any method of abstraction that you have internalized becomes conceptually free to you." (So for the sake of others, choose wisely which you will expect maintenance programmers to have internalized!) The key to the elegant solution is understanding how to manipulate data through pointers. That makes the elegant solution inappropriate to use in CS 101. It involves a method of indirection/abstraction that is emphatically NOT free to beginning programmers. It also makes the elegant solution inappropriate for most people on HN. We do not directly deal with manipulating things through pointers very much. Therefore most of us have not internalized how to do that, and the technique is very much not free to us. However Linus is a kernel developer. Anyone maintaining his code will also be a kernel developer. Kernel developers have to internalize how to handle manipulating data through pointers because their APIs require it. For example look at https://www.kernel.org/doc/html/v4.14/filesystems/index.html https://www.kernel.org/doc/html/v4.14/filesystems/index.html and see that pretty much every function gets a pointer to a data structure, and then manipulates that data structure through the pointer. Therefore every kernel developer should internalize how to manipulate data through pointers. And the elegant solution therefore becomes not just less code, it becomes conceptually simpler! And yes, any time you can replace a block of code with less code that is conceptually simpler, this shows good taste. BUT, and this is very important, it is only conceptually simpler if you've already internalized concepts around manipulating data through the indirection of a pointer. Which makes it conceptually simpler for kernel developers like Linus, but not for most programmers in other languages.

jariel 6y ago
You make a very good point, and that it has to do with the relative foundational conceptualisational ability of the types of mainteners. That's great because it kind of speaks to the crux of the problem. But the first solution does use pointers :) The second uses double pointers. I'd argue that 'even kernel maintainers' may not be so easy with the second in reality. It's probably worth it if there is a performance gain, because it's so low level. But not otherwise. But good point.
- andy_threos_io 6y ago
  The simple solution is faster.
  - btilly 6y ago
    Which solution do you think of as simple?
    - andy_threos_io 6y ago
      The cs101 is faster (and smaller), you can try yourself with gcc.

by btilly 6y ago

jariel 6y ago

You make a very good point, and that it has to do with the relative foundational conceptualisational ability of the types of mainteners. That's great because it kind of speaks to the crux of the problem. But the first solution does use pointers :) The second uses double pointers. I'd argue that 'even kernel maintainers' may not be so easy with the second in reality. It's probably worth it if there is a performance gain, because it's so low level. But not otherwise. But good point.

andy_threos_io 6y ago
The simple solution is faster.
- btilly 6y ago
  Which solution do you think of as simple?
  - andy_threos_io 6y ago
    The cs101 is faster (and smaller), you can try yourself with gcc.