ValueTuple vs. Tuple in C#: What are the Key Performance and Design Differences?

Comparing System.ValueTuple to System.Tuple

While researching decompiled C# 7 libraries, one may encounter the use of ValueTuple generics. Understanding the purpose of ValueTuples and their advantages over traditional Tuples is crucial.

Key Differences:

• Value Type vs. Reference Type: ValueTuples are value types (structs), while Tuples are reference types (classes). Value types allocate data on the stack, reducing GC pressure.
• Mutability: ValueTuples are mutable, while Tuples are immutable. This distinction affects object equality.
• Field Access: ValueTuples expose their elements through fields (e.g., Item1), while Tuples use properties.

Rationale for ValueTuples:

Introducing ValueTuples in C# 7 was driven by performance considerations:

• No Allocation Penalty: As value types, ValueTuples avoid GC overhead.
• Automatic Equality: Structs inherent optimized equality, making ValueTuples efficient for comparisons.
• Syntactic Convenience: The language introduced syntax sugar to simplify working with tuples, making their use more intuitive.

Examples:

Demonstrating the usage and benefits of ValueTuples:

public (int sum, int count) DoStuff(IEnumerable<int> values) 
{
    var res = (sum: 0, count: 0);
    foreach (var value in values) 
    { 
        res.sum += value; 
        res.count++; 
    }
    return res;
}

Using decomposing:

var result = DoStuff(Enumerable.Range(0, 10));
Console.WriteLine($"Sum: {result.sum}, Count: {result.count}");

Or using a fresh variable:

ValueTuple<int, int> valueTuple = DoStuff(Enumerable.Range(0, 10));
Console.WriteLine(string.Format(&quot;Sum: {0}, Count: {1})&quot;, valueTuple.Item1, valueTuple.Item2));

Compiler Implementation:

The compiler generates code that utilizes ValueTuple's fields internally, while providing named argument access for intuitive usage.

Conclusion:

ValueTuples offer significant performance and convenience advantages over traditional Tuples due to their value-type nature, mutability, and syntactic sugar.

The above is the detailed content of ValueTuple vs. Tuple in C#: What are the Key Performance and Design Differences?. For more information, please follow other related articles on the PHP Chinese website!