https://github.com/oktal/optional

Option type implementation in C++11
https://github.com/oktal/optional

Last synced: about 21 hours ago
JSON representation

Option type implementation in C++11

• Host: GitHub
• URL: https://github.com/oktal/optional
• Owner: oktal
• Created: 2014-05-04T18:39:40.000Z (over 10 years ago)
• Default Branch: master
• Last Pushed: 2016-04-02T11:58:45.000Z (almost 9 years ago)
• Last Synced: 2023-04-09T13:57:48.717Z (almost 2 years ago)
• Language: C++
• Size: 1.38 MB
• Stars: 12
• Watchers: 3
• Forks: 2
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

Awesome Lists containing this project

README

        
# Option type in C++

## Introduction

This is my attempt of implementing Option types in C++

Option types are very popular in functionnal programming languages like Haskell

or Scala.

An Option type is a polymorphic type that can either represent no value (None)

or some value (Some).

In functionnal programming, option types are for example used when a function

can fail or return an empty value. Haskell defines option type as follows :

```haskell

data Maybe a = Just a | Nothing

```

Scala defines it as follows :

```Scala

Option[A] = if (x == null) None else Some(x)

```

For example, when performing a hash-table or map lookup, the lookup function

would return Some(ValueType) if the key is present in the map or None if not.

That way, no null pointer or reference is involved and you can't get a

NullPointerException. Even Java 8 now has an Optional type, based on the one

provided by Guava, the google Java open source library.

A proposal has been made for C++14 to provide a std::optional type but for some

reason, it didn't make to the standard yet.

So I decided to give it a try and implement my own option type C++ with some

funny templating stuff.

## Getting started

If you want to use it, all you need to do is copy the optional.h header file

to your project source directory and guess what, that's it ! Since this is only

template, it only consists of a single header file.

As for the interface, the optional_test.cc should be straightforward as a

starting point.

## Running tests

To compile and run the tests, you just need cmake. On Unix, run the following

commands:

```

mkdir build

cd build

cmake -G "Unix Makefiles" ..

./run_optional_tests

```