Class Optional<T>

Represents an optional item of type T.
Inheritance
System.Object
Optional<T>
Inherited Members
System.Object.Equals(System.Object, System.Object)
System.Object.GetType()
System.Object.MemberwiseClone()
System.Object.ReferenceEquals(System.Object, System.Object)
System.Object.ToString()
Namespace: Maki
Assembly: Maki.dll
Syntax
public sealed class Optional<T>
Type Parameters
Name Description
T Contained item type.
Examples
The following example shows how to use an Optional object to represent a value or absence of a value. 
using Maki;
using System;

namespace Samples
{

    class Program
    {
        // Return a value only if a condition is met, otherwise Nothing
        static Optional<int> TryGet()
        {
            var value = new Random().Next(100);
            return value < 50 ? Optional.Make(value) : Optional.Nothing;
        }

        static void Main(string[] args)
        {
            var maybeInt = TryGet();

            // HasValue checks for presence of the value
            if (maybeInt.HasValue)
            {
                // Get() returns the value from the Optional
                Console.WriteLine(maybeInt.Get());
            }
            else
            {
                Console.WriteLine("maybeInt is empty");
            }
        }
    }
}

Constructors

| Improve this Doc View Source

Optional()

Creates an empty Optional.
Declaration
public Optional()
| Improve this Doc View Source

Optional(T)

Creates an Optional holding the given item.
Declaration
public Optional(T item)
Parameters
Type Name Description
T item Item to place into the Optional.

Properties

| Improve this Doc View Source

HasValue

True if the optional holds an item.
Declaration
public bool HasValue { get; }
Property Value
Type Description
System.Boolean
| Improve this Doc View Source

Nothing

Represtens an empty Optional of the given type T.
Declaration
public static Optional<T> Nothing { get; }
Property Value
Type Description
Optional<T>

Methods

| Improve this Doc View Source

Equals(Object)

Determines whether the specified object is equal to the current object.
Declaration
public override bool Equals(object obj)
Parameters
Type Name Description
System.Object obj The object to compare with the current object.
Returns
Type Description
System.Boolean True if the objects are equal.
Overrides
System.Object.Equals(System.Object)
| Improve this Doc View Source

Get()

Gets the item held by this Optional.
Declaration
public T Get()
Returns
Type Description
T Item held by this Optional.
Exceptions
Type Condition
System.InvalidCastException Thrown when the Optional does not hold an item.
| Improve this Doc View Source

GetHashCode()

Returns the hash code for this instance.
Declaration
public override int GetHashCode()
Returns
Type Description
System.Int32 Hash code.
Overrides
System.Object.GetHashCode()

Operators

| Improve this Doc View Source

Explicit(Optional<T> to T)

Explicitly casts from the given Optional to the held item type.
Declaration
public static explicit operator T(Optional<T> optional)
Parameters
Type Name Description
Optional<T> optional Optional to cast from.
Returns
Type Description
T
| Improve this Doc View Source

Implicit(T to Optional<T>)

Implicitly casts from the given item to an Optional holding the item.
Declaration
public static implicit operator Optional<T>(T item)
Parameters
Type Name Description
T item Item to cast from.
Returns
Type Description
Optional<T>
| Improve this Doc View Source

Implicit(Unit to Optional<T>)

Creates a new empty Optional.
Declaration
public static implicit operator Optional<T>(Unit unit)
Parameters
Type Name Description
Unit unit Unit type, can be Optional.Nothing.
Returns
Type Description
Optional<T>

Extension Methods