# variant

**Repository Path**: mirrors_tangrams/variant

## Basic Information

- **Project Name**: variant
- **Description**: C++11 Variant
- **Primary Language**: Unknown
- **License**: BSL-1.0
- **Default Branch**: master
- **Homepage**: None
- **GVP Project**: No

## Statistics

- **Stars**: 0
- **Forks**: 0
- **Created**: 2020-09-26
- **Last Updated**: 2025-12-14

## Categories & Tags

**Categories**: Uncategorized

**Tags**: None

## README

# Mapbox Variant

An alternative to `boost::variant` for C++11.

[![Build Status](https://secure.travis-ci.org/mapbox/variant.svg)](https://travis-ci.org/mapbox/variant)
[![Build status](https://ci.appveyor.com/api/projects/status/v9tatx21j1k0fcgy)](https://ci.appveyor.com/project/Mapbox/variant)
[![Coverage Status](https://coveralls.io/repos/mapbox/variant/badge.svg?branch=master&service=github)](https://coveralls.io/r/mapbox/variant?branch=master)

## Why use Mapbox Variant?

Mapbox variant has the same speedy performance of `boost::variant` but is faster to compile, results in smaller binaries, and has no dependencies.

For example on OS X 10.9 with clang++ and libc++:

Test | Mapbox Variant | Boost Variant
---- | -------------- | -------------
Size of pre-compiled header (release / debug) | 2.8/2.8 MB         | 12/15 MB
Size of simple program linking variant (release / debug)     | 8/24 K             | 12/40 K
Time to compile header     | 185 ms             |  675 ms


## Depends

 - Compiler supporting `-std=c++11` or `-std=c++14`

Tested with

 - g++-4.7
 - g++-4.8
 - g++-4.9
 - g++-5
 - clang++-3.4
 - clang++-3.5
 - clang++-3.8
 - Visual C++ Compiler November 2013 CTP
 - Visual C++ Compiler 2014 CTP 4

Note: get the "2013 Nov CTP" release at http://www.microsoft.com/en-us/download/details.aspx?id=41151 and the 2014 CTP at http://www.visualstudio.com/en-us/downloads/visual-studio-14-ctp-vs.aspx


## Usage

There is nothing to build, just include `variant.hpp` and
`recursive_wrapper.hpp` in your project. Include `variant_io.hpp` if you need
the `operator<<` overload for variant. Include `optional.hpp` to get an
`optional<T>` class.


## Unit Tests

On Unix systems compile and run the unit tests with `make test`.

On Windows run `scripts/build-local.bat`.


## Benchmarks

The benchmarks depend on:

 - Boost headers (for benchmarking against `boost::variant`)
 - Boost built with `--with-timer` (used for benchmark timing)

On Unix systems set your boost includes and libs locations and run `make test`:

    export LDFLAGS='-L/opt/boost/lib'
    export CXXFLAGS='-I/opt/boost/include'
    make bench


## Check object sizes

    make sizes /path/to/boost/variant.hpp