c# - Sharing a valuetuple typing between files - Stack Overflow

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I am trying to figure out the best way to share a type between files.

Basically this is what I want:

// TranspositionTable.cs
using TranspositionTableEntry = (ulong fullHash, int searchDepth, int refutationTo, int refutationFrom, double eval, NodeType type);

// Ai.cs
using TranspositionTableEntry = TranspositionTable.TranspositionTableEntry

But in Ai.cs I will get an error because TranspositionTableEntry doesn't exist.

I can think of two solutions. First I can change Ai.cs to use the same definition as in TranspositionTable.cs, and then just update it if I change the definition of this tuple.

Otherwise I can just create my own class instead of using ValueTuple. I understand how to import if I want to use a class, but I just want to use a ValueTuple since I want to avoid allocating new space on the heap every time I do that for performance reasons, since I will construct a lot of these entries.

I am trying to figure out the best way to share a type between files.

Basically this is what I want:

// TranspositionTable.cs
using TranspositionTableEntry = (ulong fullHash, int searchDepth, int refutationTo, int refutationFrom, double eval, NodeType type);

// Ai.cs
using TranspositionTableEntry = TranspositionTable.TranspositionTableEntry

But in Ai.cs I will get an error because TranspositionTableEntry doesn't exist.

I can think of two solutions. First I can change Ai.cs to use the same definition as in TranspositionTable.cs, and then just update it if I change the definition of this tuple.

Otherwise I can just create my own class instead of using ValueTuple. I understand how to import if I want to use a class, but I just want to use a ValueTuple since I want to avoid allocating new space on the heap every time I do that for performance reasons, since I will construct a lot of these entries.

• c#
• valuetuple

Share Improve this question Follow edited Mar 30 at 0:07 Alex Li asked Mar 29 at 23:00 Alex LiAlex Li 28344 silver badges1313 bronze badges 2

• 1 That exact syntax is not currently possible in c# , but consider using a record struct which is very similar – Chronicle Commented Mar 29 at 23:10
• Thanks, I didn't know about those. What's the difference between record struct and valuetuple? As far as I can tell they are the same – Alex Li Commented Mar 29 at 23:22

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3 Answers 3

Sorted by: Reset to default 3

You can use a global using.

global using TranspositionTableEntry = (ulong fullHash, int searchDepth, int refutationTo, int refutationFrom, double eval, NodeType type);

Put this at the very beginning of a file, and you will be able to use the name TranspositionTableEntry in every other file in your project.

That said, I still recommend that you create your own type. Since you are worried about heap allocations, you can write a (record) struct instead of a class.

record struct TranspositionTableEntry(ulong fullHash, int searchDepth, int refutationTo, int refutationFrom, double eval, NodeType type) {}

This will allow you to get the value tuple from the record as well as set the value tuple to a record.

public record struct TranspositionTableEntry(ulong FullHash, int SearchDepth, int RefutationTo, int RefutationFrom, double Eval, NodeType NodeType)
{                
    public static implicit operator TranspositionTableEntry((ulong fullHash, int searchDepth, int refutationTo, int refutationFrom, double eval, NodeType nodeType) entry)
    {
        return new(entry.fullHash, entry.searchDepth, entry.refutationTo, entry.refutationFrom, entry.eval, entry.nodeType);
    }
}

You're quite close! but something is missing out. In C#, you can't directly alias a ValueTuple like this across files using just a using statement unless the alias is defined in a common, shared scope (like a class or namespace both files can see).

To share a ValueTuple type across files, you can define the alias inside a static class and reuse it via a using directive in other files.

To solve this, follow the approach below:

• In a file like TranspositionTableTypes.cs, define

namespace TranspositionTable
{
    public static class Types
    {
        public static (ulong fullHash, int searchDepth, int refutationTo, int refutationFrom, double eval, NodeType type) Create(
            ulong fullHash, int searchDepth, int refutationTo, int refutationFrom, double eval, NodeType type)
        {
            return (fullHash, searchDepth, refutationTo, refutationFrom, eval, type);
        }

        public static readonly (ulong, int, int, int, double, NodeType) Default = default;
    }
}

• Then, in Ai.cs (or any other file):

using TranspositionTable;
using TranspositionTableEntry = System.ValueTuple<ulong, int, int, int, double, NodeType>;

These should sort you out I believe

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