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Modern C++ gamedev: thoughts and misconceptions

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Re: Modern C++ gamedev: thoughts and misconceptions

#31

Post by badsectoracula »

PezzaDev wrote: post #6

After years of experience writing code for games, I find that the dumbest code is the best code. It doesn't matter if it's C# or C++, whenever I've used something like reactive extensions or template metaprogramming, it has been a terrible mistake every single time. Make your code simple, dumb and verbose all the time. Avoid using any complex abstractions or any overcomplicated syntactic sugar and you'll have a codeb…

I've worked on a bunch of engines, both big AAA and small indie scaled ones and i agree with you. It is actually from this experience that i have a hard dislike for C++'s "auto" outside of cases where you can't do otherwise - it makes the code you didn't write hard to understand exactly what is going on (and sometimes error prone). Sure IDEs can show you the type if you mouse over (at least some of them), but if the type is explicitly typed you do not need to do that and you can just read instead of pause, move the mouse over the auto, read the type, then move the mouse to the next (if any), etc. And that is assuming you are reading the code inside an IDE - it doesn't work if you are reading the code in a web-based code review tool that at best can show you syntax highlighting (and it is exactly in that environment where you want the code to be at its most understandable).

Now not all features are bad, lambdas are OK when used as local functions and can make the code more readable if the alternative is to define some static function outside the current method (e.g. you want to pass some custom filter or comparator). They can certainly be abused though, but it is one of those cases where their usefulness is greater than their abuses (and i can't say the same for "auto").

For the example given... it might be a bad example, but honestly i was looking at that code for a bit and i simply cannot read it - i do not understand what is going on just by reading the code, i'd need to run it in a debugger and go through it step by step (and i've actually written texture atlas packers before). It completely fails to sell me on the "fold expressions" and "parameter packs" and it certainly doesn't look at all "elegant" to me (but note that it might be that the example is awful, not the language feature itself).

And it did make me skim through the rest of the article though since after completely failing me on all fronts at the introduction bits, i couldn't get the feel that i have any common grounds with the author.

Re: Modern C++ gamedev: thoughts and misconceptions

#32

Post by gordaco »

deepaksurti wrote: post #23
krapp wrote: post #18

Earlier quoted context omitted.

>I find that the dumbest code is the best code Not always, though. See every bug and exploit with C arrays or pointers that exists because C devs think even minimal attempts at safety are too complicated or slow, or old-style PHP code that builds SQL queries out of printf strings directly from POST values, or probably countless other examples in other languages. C++ code that uses raw pointers instead of references o…

> Not always, though. See every bug and exploit with C arrays ... That can also be perceived as a a flaw of the language design in that it does not allow one to write dumb, safe and fast code. Which are such languages in existence today? edit: fixed typos

I would say Java, which I suspect is bound to be a bit of an unpopular opinion here (I expect more startup people than enterprise denizens in HN); but the more I think about it, the more sure I'm that it fits the bill:

- Dumb: you bet. The inclusion of lambdas has shaken things a little, but usually Java code is straightforward with little space for "cleverness". The counterpoint to this, of course, would be the memes about AbstractFactoryFactoryImplementationSubclassDispatcher class names and all that, which IMHO does not represent much actual Java code out there. There are good reasons why big corps prefer Java, and readability is one of them. As a programmer, I've found it easier to jump into a Java codebase I didn't know much about than in any other language. And this has happened even when I had little experience in Java.

- Safe: yes. You have to go out of your way to be unsafe in Java. Memory allocation is done for you and the try-with-resources idiom is almost as good as C++ RAII.

- Fast: also yes. Usually about 2x or 3x the run time of C/C++ code, some times even less.

Re: Modern C++ gamedev: thoughts and misconceptions

#33

Post by elbows »

MauranKilom wrote: post #28
saagarjha wrote: post #4

Really the “problem” here is that C++’s functional constructs will never allocate memory, giving them somewhat strange signatures that don’t really conduce themselves well to typical functional concepts. At compile time there is no such goal and as such some of these constructs can only be found there.

According to https://en.cppreference.com/w/cpp/algorithm/stable_sort : > This function attempts to allocate a temporary buffer equal in size to the sequence to be sorted. If the allocation fails, the less efficient algorithm is chosen. Or is this not what you consider a "functional construct"?

It's more of an issue with things like std::transform or std::copy_if. Ergonomically, it's nice if these kinds of functions either allocate and return a new container, or return an iterator that yields the elements of the result.

But the C++ versions of these take the result location as an argument. It makes chaining them together a hassle because you have to create all the intermediate containers explicitly.

I think there are good reasons for the STL to work this way, but it can make programming in a functional style pretty inconvenient compared to a lot of other languages.

Re: Modern C++ gamedev: thoughts and misconceptions

#36

Post by PezzaDev »

microtherion wrote: post #26
PezzaDev wrote: post #6

After years of experience writing code for games, I find that the dumbest code is the best code. It doesn't matter if it's C# or C++, whenever I've used something like reactive extensions or template metaprogramming, it has been a terrible mistake every single time. Make your code simple, dumb and verbose all the time. Avoid using any complex abstractions or any overcomplicated syntactic sugar and you'll have a codeb…

> Make your code simple, dumb and verbose all the time This is a frequently encountered argument, and sure, if you look at any single line , it looks very obvious what it does. But I would argue that verbosity and lack of abstraction has severe drawbacks for a programmer's ability to understand the overall codebase , and it is disastrous for long term maintainability. You start out with 20 identical pieces of boilerp…

No coding approach will ever solve an issue caused by a lack of discipline.

Re: Modern C++ gamedev: thoughts and misconceptions

#37

Post by hhmc »

MauranKilom wrote: post #24
HelloNurse wrote: post #9

Earlier quoted context omitted.

C++ fold expressions, the main C++ feature the article covers, are simple and dumb (at least, enough to use them) but not verbose, and definitely harder to get wrong than a much more verbose for loop.

I love fold expressions, but if you're inside a variadic template, you've long left the realms of "simple and dumb". IMO. I mean, they're only readable to people who have dabbled in variadic templates in their free time. That's how many people on your (future) team?

> I mean, they're only readable to people who have dabbled in variadic templates in their free time. That's how many people on your (future) team?

This line of reasoning is vacously true for any syntax and semantics though. Move semantics and rvalue reference are only readable to people that have taken the time to understand them -- they're undoubtably useful though.

Re: Modern C++ gamedev: thoughts and misconceptions

#38

Post by Riverheart »

microtherion wrote: post #27
lazypenguin wrote: post #15

Earlier quoted context omitted.

Matches my experience as well in the hobby gamedev realm. I can give an anecdote, I’m involved in a “private server” dev community for an old niche MMO from 2003. There exists 3 codebases: first the original code written in a windows-style C++ with heavy use of inheritance, custom collections, Hungarian notation, etc. The second is a collaborative open source version that is written in a naive/basic C++ style (e.g. c…

So, naive code attracts naive programmers? I'm not sure this is the ringing endorsement you take it to be. I should also add that Hungarian notation is the prototypical example of dumb, verbose code, that wants to make individual lines easier to understand by dragging type information into every single variable name.

Or you know, people who respect their time.

Re: Modern C++ gamedev: thoughts and misconceptions

#39

Post by KallDrexx »

badsectoracula wrote: post #31
PezzaDev wrote: post #6

After years of experience writing code for games, I find that the dumbest code is the best code. It doesn't matter if it's C# or C++, whenever I've used something like reactive extensions or template metaprogramming, it has been a terrible mistake every single time. Make your code simple, dumb and verbose all the time. Avoid using any complex abstractions or any overcomplicated syntactic sugar and you'll have a codeb…

I've worked on a bunch of engines, both big AAA and small indie scaled ones and i agree with you. It is actually from this experience that i have a hard dislike for C++'s "auto" outside of cases where you can't do otherwise - it makes the code you didn't write hard to understand exactly what is going on (and sometimes error prone). Sure IDEs can show you the type if you mouse over (at least some of them), but if the…

I wonder how wide spread dislike of "auto" is in c++ (I've seen that a few places) when the equivalent type inference has become fairly standard and preferred in other languages like C#, Rust, Go, etc...

Re: Modern C++ gamedev: thoughts and misconceptions

#40

Post by hhmc »

sharpneli wrote: post #34

There was a good comparison about those floating around: https://imgur.com/a/u1N4Fpy For me the code on the right is far more readable and easier to understand.

The code on the right feels in mildly bad faith to me.

  - consts are dropped
  - variable definitions are merged onto multiple lines
  - usefully named constants like `nPixels`, `nBytes` are elided
  - the `idx` lambda is inlined
The net effect, for an initial skim, is that the code on the right looks terser and simpler. But in reality many of the "short cuts" hurt the long term quality of the code.
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