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Why Memory and ReadOnlyMemory are struct? RRS feed

  • 問題

  • Why the types Memory and ReadOnlyMemory are struct instead of class? As they generally are used on asynchronous calls and are moved to the heap.
    2021年6月8日 下午 02:18

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  • Hi

    Span<Message> valSpan stackalloc Message[1] ;
    valSpan[0] =Message {Header = 123, Data = 456 } ;
    Span<byte> bytes = MemoryMarshal.Cast<Message, byte>(valSpan); // has a length of 8
    Note that I am using Span<T> here. You can do much the same with Memory<T> if necessary - but you need a support array or similar, which will usually require allocation - if not the array, then a custom MemoryManager<T> :

    var arr = new message[1] ;
    arr[0] = new message {Header = 123, Data = 456 } ;
    Memory<byte> bytes = MemoryMarshal.Cast<Message, byte>(arr); // has a length of 8
    Essentially, you are very close here:

    MemoryMarshal.CreateReadOnlySpan(ref message, 1)
    The trick, however, is to use MemoryMarshal.Cast<TFrom

    • 已提議為解答 Serocan67 2022年1月16日 下午 10:42
    • 已取消提議為解答 Serocan67 2022年1月16日 下午 10:43
    • 已提議為解答 Serocan67 2022年1月16日 下午 10:43
    • 已取消提議為解答 Serocan67 2022年1月16日 下午 10:44
    • 已提議為解答 Serocan67 2022年1月16日 下午 10:44
    2021年6月8日 下午 02:42
  • The only significant difference between a structure and a class is the default status of members.  In a structure, they are public while in a class they are private.

    Declared objects do not occupy space on the heap.   Only allocated (via new, malloc, etc) objects do.

    For obvious reasons, read only memory can only bu used for declared object defined as const or things like string literals which are non-modifiable.

    2021年6月10日 上午 12:26
  • Have you got the answer?
    2021年6月26日 上午 06:44
  • Is your problem solved well?
    2021年6月28日 上午 03:07
  • It wasn't only that though, there were a variety of reasons why they didn't take the alternate route, and given the facts.
    2022年1月10日 上午 09:58
  • Structs have lower overhead than classes and perform better. Since the goal of the Memory, ReadOnlyMemory, Span, and ReadOnlySpan structs is to help improve code performance, it would be kind of counter productive to use a high overhead mechanism.
    • 已編輯 Mark_Jonas 2022年1月11日 上午 12:03 edit
    2022年1月11日 上午 12:02
  • In fact, the difference between class and structural is not very big. In structural members, by default, members are public, and in class ones, they are private. That's all :) And recently I started to get involved in gaming. I find the top games on romsify.com and then I hang out for hours. It helps me to relax after long programming :)
    2022年1月11日 下午 11:17
  • Hello, Structs have lower overhead than classes and perform better. Since the goal of the Memory, ReadOnlyMemory, Span, and ReadOnlySpan structs is to help improve code performance, it would be kind of counter productive to use a high overhead mechanism.
    2022年1月13日 下午 12:55
  • Why am I having issues running some games on my PC when there is nothing wrong with the system?
    2022年1月15日 下午 07:29
  • It wasn't only that though, there's a variety of reasons why they didn't take the alternate route, and given facts change their direction at that time.
    2022年1月19日 上午 05:58
  • The difference is that structs have lower overhead and perform better. 
    2022年1月24日 下午 07:57
  • There may be a variety of reasons they'd likely have faced lawsuits from those who's apps they'd broken.



    2022年2月4日 上午 05:17
  • The object type from which the contiguous region of memory will be read.

    2022年2月8日 下午 06:27
  • I enjoy the efforts you have put in this, thanks for all the great articles.
    2022年2月9日 上午 09:58
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    2022年2月9日 上午 10:00
  • ReadOnlyMemory<T>(T[])
    Creates a new memory region over the entirety of the target array.

    ReadOnlyMemory<T>(T[], Int32, Int32)
    Creates a new memory region over the portion of the target array beginning at a specified position and including a specified number of elements.
    2022年2月9日 下午 01:28
  • Structs have lower overhead than classes and perform better. Since the goal of the Memory, ReadOnlyMemory, Span, and ReadOnlySpan structs is to help improve code performance, it would be kind of counter productive to use a high overhead mechanism.
    2022年2月14日 上午 05:42
  • Why use a struct instead of a class?
    2022年2月15日 上午 11:07
  • Thanks you so much for your help....
    2022年2月19日 上午 05:03
  • As struct is the data type that represents the data structures. Struct includes a constants, fields, methods, parameterized constructor, static constructor, and properties as well. 

    A class is the category of object that defines all the common properties of different object that belongs to it.

    Structs are stored in a stack whereas Classes are stored on the heap. Might for this reasons Memory and Read Only Memory are used for object declaration.

    2022年2月25日 上午 07:42
  • Is your problem solved well?
    2022年3月18日 上午 06:33
  • As struct is the data type that represents the data structures. Struct includes a constants, fields, methods, parameterized constructor, static constructor, and properties as well. 

    A class is the category of object that defines all the common properties of different object that belongs to it.

    Structs are stored in a stack whereas Classes are stored on the heap. Might for this reasons Memory and Read Only Memory are used for object declaration.

    Great, thanks for this
    2022年3月18日 上午 09:30
  • Structs are more lightweight than classes, do better at performance and is easier to use. This means it might be counterintuitive to use a class with a big overhead for the Memory, ReadOnlyMemory, Span and ReadOnlySpan structs.
    2022年8月6日 上午 06:30