Class Decorator<TIn, TOut>

Namespace

PatternKit.Structural.Decorator

Assembly

PatternKit.Core.dll

Fluent, allocation-light decorator that wraps a component and applies layered enhancements via ordered decorators. Build once, then call Execute(in TIn) to run the component through the decorator pipeline.

public sealed class Decorator<TIn, TOut>

Type Parameters

TIn

Input type passed to the component.

TOut

Output type produced by the component.

Inheritance

object

Decorator<TIn, TOut>

Inherited Members

object.Equals(object)

object.Equals(object, object)

object.GetHashCode()

object.GetType()

object.ReferenceEquals(object, object)

object.ToString()

Extension Methods

CoercerExtensions.Coerce<T>(object?)

Examples

var decorator = Decorator<int, int>.Create(static x => x * 2)
    .Before(static x => x + 1)  // Add 1 before
    .After(static x => x * 10)   // Multiply result by 10
    .Build();

var result = decorator.Execute(5); // ((5 + 1) * 2) * 10 = 120

Remarks

Mental model: A base component is wrapped by zero or more decorators. Each decorator can:

• Transform the input before passing it to the next layer (Decorator<TIn, TOut>.BeforeTransform).
• Transform the output after receiving it from the next layer (Decorator<TIn, TOut>.AfterTransform).
• Wrap the entire execution with custom logic (Decorator<TIn, TOut>.AroundTransform).

Decorators are applied in the order they are registered. The innermost layer is the base component.

Immutability: After Build(), the decorator chain is immutable and safe for concurrent reuse.

Methods

Create(Component)

Creates a new Decorator<TIn, TOut>.Builder for constructing a decorated component.

public static Decorator<TIn, TOut>.Builder Create(Decorator<TIn, TOut>.Component component)

Parameters

component Decorator<TIn, TOut>.Component

The base component to decorate.

Returns

Decorator<TIn, TOut>.Builder

A new Decorator<TIn, TOut>.Builder instance.

Examples

var dec = Decorator<string, int>.Create(static s => s.Length)
    .Before(static s => s.Trim())
    .After(static (_, len) => len * 2)
    .Build();

var result = dec.Execute("  hello  "); // 10

Execute(in TIn)

Executes the decorated component with the given input.

public TOut Execute(in TIn input)

Parameters

input TIn

The input value (readonly via in).

Returns

TOut

The result after applying all decorators in order, ending with the base component execution.

Remarks

The execution flows outward-to-inward for Decorator<TIn, TOut>.BeforeTransform decorators (transforming input), then executes the base component, then flows inward-to-outward for Decorator<TIn, TOut>.AfterTransform decorators (transforming output). Decorator<TIn, TOut>.AroundTransform decorators control the entire flow at their layer.