New Feature in Dot

1. Params Collections

🧠 What’s New?

The params modifier in C# 13 now supports more than just arrays.
You can now pass:

• IEnumerable<T>

• IReadOnlyCollection<T>

• IReadOnlyList<T>

• ICollection<T>

• IList<T>

• Span<T>, ReadOnlySpan<T>

This improves flexibility and reduces heap allocations when using Span<T> types (stack-allocated).

✅ Before C# 13:

void PrintNumbers(params int[] numbers) { ... }

✅ In C# 13:

void PrintNumbers(params IEnumerable<int> numbers) { ... }
 
// Or even:
void Process(params Span<int> data) { ... }

💡 Benefit:

Improves performance by reducing memory allocations (especially with Span<T>), and allows more types in params.

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2. New Lock Type

🧠 What’s New?

A new Lock class is introduced that offers:

• Better readability

• Cleaner scope-based locking

• Additional control methods

🛠️ Features:

• Enter(), Exit(): Manual lock control

• TryEnter(): Attempt lock without blocking

• EnterScope(): Scoped locking with using

• IsHeldByCurrentThread: Check thread ownership

✅ Example:

var myLock = new Lock();
using (myLock.EnterScope())
{
    // Thread-safe code here
}

💡 Benefit:

Makes multithreaded code cleaner and safer.

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3. New Escape Sequence \e

🧠 What’s New?

A new escape sequence \e has been added, representing the ESC (Escape) character (U+001B).

✅ Example:

string esc = "\e[1;31mRed Text\e[0m";
Console.WriteLine(esc);

💡 Use Cases:

• Terminal commands

• Low-level protocols

• Device communication (e.g., label printers)

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4. Init Arrays with Index Operator ^

🧠 What’s New?

You can now use the index-from-end operator (^) when initializing arrays.

✅ Example (New):

int[] data = new int[5];
data[^1] = 99;  // Sets last element to 99

Previously, you couldn’t use ^ in initializers; now you can!

💡 Benefit:

Avoids manual index calculation when working with array ends.

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5. Relaxed Constraints on ref struct and ref Variables

🧠 What’s New?

• ref struct can now be used as generic type parameters

• ref locals allowed in async and iterator methods

✅ Example:

void ProcessSpan<T>(T span) where T : ref struct
{
    // Efficient handling of Span<T> or similar
}

💡 Benefit:

Improves performance and flexibility in low-level and high-performance code, especially when working with spans or buffers.

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✅ Summary (TL;DR)

Feature	Description
1. Params Collections	Use collections (not just arrays) with params
2. New Lock Type	Better thread sync with Lock class
3. Escape Sequence \e	Shorthand for ESC character (U+001B)
4. Init Array with ^	Use index-from-end in initializers
5. Ref Struct Relaxation	Generic & async support for ref struct