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How to Make Custom Native Collections

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We’ve seen how NativeArray works, but what if we want more kinds of native collections? Unity 2018.1 only has that one, but you can make your own! Today’s article shows exactly how to do that.

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Loops in IL2CPP

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There are many permutations of loops we can write, but what do they compile to? We should know the consequences of using an array versus a List<T>, for versus foreach, caching Length, and other factors. So today’s article dives into the C++ code that IL2CPP outputs when we write these various types of loops to examine the differences. We’ll even go further and look at the ARM assembly that the C++ compiles to and really find out how much overhead our choices are costing us.

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Should You Cache Array.Length and List.Count?

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Every time I see for (var i = 0; i < array.Length; ++i) I wonder if accessing that Length property is slow. Should I cache it? It’s comforting to know that for (int i = 0, len = array.Length; i < len; ++i) is only dealing with local variables except on the first loop. Local variables must be faster, right? Likewise, I wonder the same thing about List<T>.Count. I finally got around to running a test to see if caching these length properties makes any performance difference. The answers might surprise you!

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Enumerables Without the Garbage: Part 7

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Today we’ll wrap up the iterator series by finishing up porting C++’s <algorithm> header. We end up with a library of functions for common LINQ-style algorithms but without any of the garbage creation that slows our games down. Read on for the source and examples!

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Enumerables Without the Garbage: Part 6

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We’re nearing the end of the series to build a no-garbage replacement for System.Linq. Today we tackle functions that work on already-sorted ranges and functions that work on ranges that are in heap order. These include common set operations like “union” and “intersection”. Read on to see how to use them and for the updated library that you can use to eliminate your garbage creation!

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Enumerables Without the Garbage: Part 5

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This week we continue with iterators to get the functionality of IEnumerable without the nasty garbage creation. This week the little iterator library gets support for sorting and binary searching. Read on for the details!

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Enumerables Without the Garbage: Part 4

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Back from a brief break, we pick up this week by finishing up the “modifying sequence operations” with some gems like RandomShuffle and go through the “partitions” category with functions like Partition and IsPartitioned. These are all solid algorithms with a lot of potential uses, so read on to see how to use them with iterators and for the source code that implements them!

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Enumerables Without the Garbage: Part 3

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Continuing the series this week we’ll delve into the iterator functions that modify the sequence. This includes handy tools like Copy, SwapRanges, and Transform. Of course this is all done without creating any garbage! Read on to see how and for the full source code.

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Enumerables Without the Garbage: Part 2

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Last week’s article introduced the concept of iterators as an alternative to the GC-heavy IEnumerable. Today’s article expands the iterator library to include a bunch of more functions to make it useful. Think of these like the extension functions in System.Linq: Any, IndexOf, etc. These have all been tailored to iterators and none of them will create any garbage whatsoever.

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Enumerables Without the Garbage: Part 1

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In C#, just about everything is an IEnumerable. Since LINQ syntax, foreach loops, and the System.Linq namespace are all designed to work with IEnumerable, you’ve got lots of tools to use. Unfortunately, the core of IEnumerable is the GetEnumerator function which usually creates garbage and eventually causes memory fragmentation and GC framerate spikes. Do we simply stop using all of these nice tools? Normally the answer is “yes”, but today’s article shows you another way.

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