The standard library allocators are one of the more mysterious parts of namespace std, as well as one of the more flexible parts. In this "under construction" article and GitHub repo, Thomas Köppe undertakes to demystify the feature.

A visitor’s guide to C++ allocators (repo)

by Thomas Köppe

From the README:

This repository contains a collection of documents that describe the allocator concept in the standard library of C++11 and beyond. The main guide covers the following topics.

• Allocator traits
• Statefulness
• Fancy pointers
• Allocator propagation in breadth (container copy, POC{CA,MA,S}) and depth (scoped_allocator_adaptor)

Start reading with the main guide.

Furthermore, there are several worked-out end-to-end examples:

• Using allocators: A simple arena allocator
• Writing containers: A simple dynamic container
• Writing fancy pointers: A simple offset pointer

The code for the end-to-end examples is available separately in the example_code directory.