📘 ModernBCL.Core.BLC

Modern Polyfills for Legacy .NET Framework 4.8 / 4.8.1

ModernBCL.Core.BLC brings high-performance, zero-allocation replacements for missing modern BCL APIs to legacy .NET Framework apps — enabling performance and clarity normally available only in .NET 7/8.

This library is especially useful for:

• Enterprise systems that must stay on .NET Framework 4.8 / 4.8.1
• Developers wanting modern C# coding patterns on legacy frameworks
• Teams needing high-quality hashing or safe guard clauses
• Projects migrating from .NET Framework → .NET Core but needing parity

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🎯 Project Goals

ModernBCL.Core.BLC provides:

✔ High-performance hashing

• Drop-in System.HashCode polyfill (for .NET Framework only)
• Modern, order-sensitive HashCode.Combine()
• HashAccumulator (32-bit) and HashAccumulator64 (64-bit)
• Extremely low collision rates
• Zero allocations

✔ Modern guard clauses

• Clean replacement for repetitive null/empty/whitespace checks
• Fluent Guard.Against() API
• Polyfilled [CallerArgumentExpression] attribute
• No need to manually pass parameter names

✔ Cleaner code, safer APIs

• Modern BCL patterns for older frameworks
• Full parity with .NET 6/7/8 guard & hashing behavior (where appropriate)

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🚀 Installation

Install via NuGet:

.NET CLI

dotnet add package ModernBCL.Core.BLC --version 1.2.0

Visual Studio Package Manager Console

Install-Package ModernBCL.Core.BLC -Version 1.2.0

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📦 Compatibility

Target	Status	Notes
.NET Framework 4.8 / 4.8.1	✔ Supported	HashCode polyfill is active
.NET 8+ / .NET Core	✔ Supported	Uses native System.HashCode (polyfill disabled)
NuGet Package	✔ Multi-target	net48; net481; net8.0

ModernBCL intelligently switches behavior:

• Under net48/net481 → uses ModernBCL HashCode polyfill
• Under net8+ → uses native framework HashCode

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💻 Usage Examples

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1. ⚡ High-Performance Hash Codes

using System;

public class ProductKey
{
    public string ProductId { get; }
    public string Color { get; }
    public int Size { get; }

    public override int GetHashCode()
    {
        return HashCode.Combine(ProductId, Color, Size);
    }
}

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2. 🔐 Modern Guard Clauses

using ModernBCL.Core.Guards;

public class DependencyContainer
{
    public DependencyContainer(object service, string clientName)
    {
        _service = Guard.Against(service).Null();
        _clientName = Guard.Against(clientName).NullOrWhiteSpace();
    }
}

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⚙️ How It Works

🧮 HashCode Polyfill

• Only used under .NET Framework
• Fully deterministic
• Zero allocations
• Based on HashAccumulator

🛡 Guard Polyfills

• Provides [CallerArgumentExpression] for .NET Framework
• Modern fluent API on legacy runtimes

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📊 Benchmarks Included

Benchmark results generated to:

BenchmarkDotNet.Artifacts/results/

Formats:

• .html
• .md
• .csv

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🧾 Changelog

Version 1.2.0 (Latest)

✔ Added multi-targeting: net48; net481; net8.0
✔ Added HashAccumulator64 (64-bit hashing)
✔ Added comparer suite
✔ Added full Guard API
✔ Added fuzz tests
✔ Added benchmarks
✔ Improved HashCode polyfill

Version 1.1.1

✔ Support for both net48 and net481

Version 1.1.0

✔ ThrowHelper + polyfill attributes

Version 1.0.0

✔ Initial release with HashCode polyfill

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📄 License

MIT License.