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68 lines
5.7 KiB
Markdown
68 lines
5.7 KiB
Markdown
# Boost PolyCollection library
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[](https://github.com/boostorg/poly_collection/tree/master) [](https://github.com/boostorg/poly_collection/actions/workflows/ci.yml) [](https://drone.cpp.al/boostorg/poly_collection) [](https://ci.appveyor.com/project/joaquintides/poly-collection/branch/master) [](https://pdimov.github.io/boostdep-report/master/poly_collection.html) [](https://www.boost.org/doc/libs/master/doc/html/poly_collection.html) [](https://regression.boost.org/master/developer/poly_collection.html)<br/>
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[](https://github.com/boostorg/poly_collection/tree/develop) [](https://github.com/boostorg/poly_collection/actions/workflows/ci.yml) [](https://drone.cpp.al/boostorg/poly_collection) [](https://ci.appveyor.com/project/joaquintides/poly-collection/branch/develop) [](https://pdimov.github.io/boostdep-report/develop/poly_collection.html) [](https://www.boost.org/doc/libs/develop/doc/html/poly_collection.html) [](https://regression.boost.org/develop/developer/poly_collection.html)<br/>
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[](https://www.boost.org/users/license.html) <img alt="C++11 required" src="https://img.shields.io/badge/standard-C%2b%2b11-blue.svg"> <img alt="Header-only library" src="https://img.shields.io/badge/build-header--only-blue.svg">
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**Boost.PolyCollection**: fast containers of polymorphic objects.
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Typically, polymorphic objects cannot be stored *directly* in regular containers
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and need be accessed through an indirection pointer, which introduces performance
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problems related to CPU caching and branch prediction. Boost.PolyCollection
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implements a
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[novel data structure](http://www.boost.org/doc/html/poly_collection/an_efficient_polymorphic_data_st.html)
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that is able to contiguously store polymorphic objects without such indirection,
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thus providing a value-semantics user interface and better performance.
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Four *polymorphic collections* are provided:
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* [`boost::base_collection`](http://www.boost.org/doc/html/poly_collection/tutorial.html#poly_collection.tutorial.basics.boost_base_collection)
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* [`boost::function_collection`](http://www.boost.org/doc/html/poly_collection/tutorial.html#poly_collection.tutorial.basics.boost_function_collection)
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* [`boost::any_collection`](http://www.boost.org/doc/html/poly_collection/tutorial.html#poly_collection.tutorial.basics.boost_any_collection)
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* [`boost::variant_collection`](http://www.boost.org/doc/html/poly_collection/tutorial.html#poly_collection.tutorial.basics.boost_variant_collection)
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dealing respectively with classic base/derived or OOP polymorphism, function wrapping
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in the spirit of `std::function`, so-called
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[*duck typing*](https://en.wikipedia.org/wiki/Duck_typing) as implemented by
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[Boost.TypeErasure](http://www.boost.org/libs/type_erasure),
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and variant-like _closed polymorphism_.
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## Learn about Boost.PolyCollection
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* [Online docs](http://boost.org/libs/poly_collection)
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* [Seminal article at bannalia.blogspot.com](http://bannalia.blogspot.com/2014/05/fast-polymorphic-collections.html)
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## Install Boost.PolyCollection
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* [Download Boost](https://www.boost.org/users/download/) and you're ready to go (this is a header-only library requiring no building).
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* Using Conan 2: In case you don't have it yet, add an entry for Boost in your `conanfile.txt` (the example requires at least Boost 1.86):
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```
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[requires]
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boost/[>=1.86.0]
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```
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<ul>If you're not using any compiled Boost library, the following will skip building altogether:</ul>
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```
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[options]
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boost:header_only=True
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```
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* Using vcpkg: Execute the command
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```
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vcpkg install boost-poly-collection
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```
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* Using CMake: [Boost CMake support infrastructure](https://github.com/boostorg/cmake)
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allows you to use CMake directly to download, build and consume all of Boost or
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some specific libraries.
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## Support
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* Join the **#boost** discussion group at [cpplang.slack.com](https://cpplang.slack.com/)
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([ask for an invite](https://cppalliance.org/slack/) if you’re not a member of this workspace yet)
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* Ask in the [Boost Users mailing list](https://lists.boost.org/mailman/listinfo.cgi/boost-users)
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(add the `[poly_collection]` tag at the beginning of the subject line)
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* [File an issue](https://github.com/boostorg/poly_collection/issues)
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## Contribute
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* [Pull requests](https://github.com/boostorg/poly_collection/pulls) against **develop** branch are most welcome.
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Note that by submitting patches you agree to license your modifications under the [Boost Software License, Version 1.0](http://www.boost.org/LICENSE_1_0.txt).
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