EnumerablePrinter

A lightweight, reflection-aware formatter for debugging .NET objects, collections, and dictionaries.

EnumerablePrinter is intentionally focused on one job: printing data in a clear, predictable, human-readable format for console output, logging, and quick inspection during development. It does not try to duplicate features already provided by the .NET framework.

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Why this project exists

The library was deliberately narrowed to a single purpose:

• print common .NET values clearly
• render nested structures recursively
• show object properties in a debug-friendly way
• keep output readable and consistent
• avoid re-implementing framework features that already exist elsewhere

This makes the library easier to understand, easier to maintain, and better aligned with real debugging workflows.

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Features

• pretty-prints arrays, lists, sets, and other IEnumerable values
• prints IDictionary entries as key/value output
• reflects public instance properties for complex objects
• handles string, byte[], and IEnumerable<char> gracefully
• prevents circular-reference recursion from causing runaway output
• supports console output or any TextWriter
• supports configurable output through PrintOptions
• exposes ObjectFormatter for formatting without console output
• provides a chainable Format() extension that returns diagnostic text without writing it
• keeps the public API intentionally small and focused
• includes optional Python-style slicing through the separate EnumerablePrinter.Linq project
• includes a separate Roslyn analyzer project for flagging Print() calls in performance-sensitive code

Optional sequence slicing

The EnumerablePrinter.Linq project adds a focused Slice() extension for IEnumerable<T> values. It supports optional start, end, and positive step parameters, including negative indices.

Reference the project alongside EnumerablePrinter:

<ProjectReference Include="..\..\src\EnumerablePrinter.Linq\EnumerablePrinter.Linq.csproj" />

Then use it with the printer:

using EnumerablePrinter.Extensions;
using EnumerablePrinter.Linq;

var numbers = new[] { 10, 20, 30, 40, 50, 60 };

numbers.Slice(start: 1, end: 4).Print();
// [20, 30, 40]

numbers.Slice(step: 2).Print();
// [10, 30, 50]

var fruits = new[] { "Apple", "Banana", "Cherry", "Date", "Elderberry" };
fruits.Slice(start: -3).Print();
// ["Cherry", "Date", "Elderberry"]

Positive-index slices stream from the source; slices using negative indices buffer the source so they can resolve positions from the end. step must be greater than zero.

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Installation

dotnet add package EnumerablePrinter

Supported frameworks

The core EnumerablePrinter package targets netstandard2.0 and net8.0. This supports .NET Framework 4.7.2 and later, .NET Core, and modern .NET applications without maintaining separate formatter implementations.

The optional EnumerablePrinter.Linq package targets the same frameworks. The analyzer remains a separate netstandard2.0 project.

The repository includes a .NET Framework 4.7.2 compatibility smoke test under tests/EnumerablePrinter.Compatibility.Tests. Run it on Windows with:

dotnet build tests/EnumerablePrinter.Compatibility.Tests/EnumerablePrinter.Compatibility.Tests.csproj -c Release
& .\tests\EnumerablePrinter.Compatibility.Tests\bin\Release\net472\EnumerablePrinter.Compatibility.Tests.exe

Roslyn analyzer

The repository also contains EnumerablePrinter.Analyzers, a separate netstandard2.0 Roslyn analyzer project. It defines diagnostic EP0001, which reports calls to EnumerablePrinter.Extensions.PrintExtensions.Print and suggests explicit formatting or logging instead.

The analyzer is maintained separately from the core EnumerablePrinter package. To use it from a local checkout, add a project reference to src/EnumerablePrinter.Analyzers/EnumerablePrinter.Analyzers.csproj in the consuming project.

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Basic usage

using EnumerablePrinter.Extensions;

var numbers = new[] { 1, 2, 3, 4, 5 };
numbers.Print();
// [1, 2, 3, 4, 5]

var person = new { Name = "Wayne", Age = 42 };
person.Print();
// {Name: "Wayne", Age: 42}

var metadata = new Dictionary<string, int>
{
    ["One"] = 1,
    ["Two"] = 2
};
metadata.Print();
// {"One": 1, "Two": 2}

Explicit console output

new[] { 1, 2, 3 }.PrintToConsole();

This follows the same formatting path as Print(), but makes the console intent explicit.

Formatting without output

Use Format() when you want a diagnostic string to pass to a logger or write to a destination you choose. It uses the same formatting rules and PrintOptions as Print(), but does not write output:

using EnumerablePrinter.Abstractions;
using EnumerablePrinter.Extensions;

var details = request.Format(new PrintOptions
{
    Pretty = true,
    MaxDepth = 4,
    MaxItems = 50
});

logger.LogError(exception, "Request details: {Details}", details);

Format() returns diagnostic text, not JSON or HTML-encoded content. Encode it at the HTML output boundary, and use a serializer when you need a serialization contract.

ObjectFormatter remains available when you prefer a static entry point or need to write directly to a TextWriter:

using EnumerablePrinter;

var text = ObjectFormatter.Format(new[] { 1, 2, 3 });
// [1, 2, 3]

Configuring output

Use PrintOptions when you need limits or readable multiline output. The default remains compact output for compatibility.

using EnumerablePrinter.Abstractions;
using EnumerablePrinter.Extensions;

var report = new
{
    Title = "Inventory",
    Items = new[] { "Keyboard", "Mouse", "Monitor" }
};

var options = new PrintOptions
{
    Pretty = true,
    IndentSize = 4,
    MaxItems = 10
};

report.Print(options: options);

PrintOptions also supports maximum recursion depth, optional null and private-member handling, and collection item limits. Pass the same options to PrintToConsole(options) when writing directly to the console.

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Output conventions

The formatter uses a consistent debug-printing style:

• collections render as [ ... ]
• dictionaries render as { "key": value }
• object properties render as PropertyName: value
• strings are quoted
• null renders as null
• circular references render as <Circular Reference>

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Repository workflow

The project is organized around a clean release and publish split:

• release scripts handle versioning and git tagging
• deploy scripts handle build, test, packaging, and NuGet publishing

See the script guide in scripts/README.md for the full flow and dry-run usage.

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Final project direction

The current design intentionally avoids adding collection helpers or framework duplicates. The library remains focused on the single, practical task it does well: iterating over values and printing them in a clear, debug-friendly form.

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License

MIT

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Links

• NuGet: EnumerablePrinter on NuGet
• Repository: EnumerablePrinter on GitHub