The 4 'secret' C# keywords that you shouldn't use

Hello everybody I'm Nick and in this video I am going to talk about the 4 secret or hidden keywords in C#. Those keywords are not part of the spec and there is no official documentation by Microsoft about them at all. In this video I will show you what they do and how you could use them.

Timestamps
Intro - 0:00
__makeref - 0:43
__refvalue & __reftype - 6:26
__arglist - 7:50

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#dotnet #secretkeywords #csharp

[lordshoe]

So __arglist is kind of like the 'params' keyword, but with pointer shenanigans?

[abeker]

Are items in arrays always stored exactly adjacent, or is the compiler allowed to add some padding in between? For example if there's a struct of 7 bytes where one member is an int, are there cpu architectures where the int must be at an address that's a multiple of 4?

[bartekm]

Small thing, you have a typo in the timestamps. You wrote __rettype instead of __reftype.
Great job on the video as always!

[diego_samano]

05:10 sizeOfB is using sizeof(SomeStructA). Very interesting keywords.

[arunkumarsingh]

Hi is there any difference in Dot net programming on AMD Ryzen and Intel processor in terms of performance and compatibility? Or both works same with dotnet ?

[ZachLayne-di]

You type in "C# hidden keywords" in Google and I'm the first search result! WOO.

When I was contracting at MS a long, long time ago, I stumbled across an obscure MSDN example that had __argslist in it, I believe. That's how I found out about them. I believe I even had to ping the dev that wrote the example, and there was 0 way that should have slipped through into documentation.

[mastermati]

Can't we use 'fixed' keyword to pin the array?

[amrosamy]

In asp dotnet
AsyncLocal<T> is used to hold the context within the HttpContextAccessor
Is there a way to provide the same functionality of AsyncLocal<T> but through the DI?
It's kind of scoped object but without a real DI scope!

[Khitiara_]

Isnt most of this superseded by the unmanaged generic constraint in newer c# ?

[saniel]

I heard that __arglist also doesn't produce GC Allocs, which may be nice if you're super concerned