Learn STL

Learning about the C++ Standard Library by Implementation

Ever wondered how std::tuple is implemented? How std::get works? Well I started implementing this to find out just that.

The standard library heavily relies on many C++ Idioms and unusual language features, by implementing the library you can get a bit more familiar with them!

Each of the components have documentation in /docs explaining how they work, what idioms the use, and whats interesting about them.

Hopefully you'll find this an interesting read!

Feel free to submit a PR adding more components or improving library / documentation!

Vocab Types

any

Any is the de-facto type-erasure method in C++, it provides type-safe container for single values of any type. The implementation provides an introduction to polymorphism in C++.

optional

How can you store an object without a default-constructor on the stack? Well with a union is how, but what is this weird special type.

tuple

Tuple heavily depends on variadic templates and std::index_sequence, and isn't obvious how its implemented. It's a refreshing look at features which aren't used day-to-day.

variant

Another component thats heavily dependent on variadic templates, it employs more template metaprogramming tricks than tuple. It also provides an interesting use case of aligned_storage.

Containers

array

Array is deceptively simple, but how are its constructors and destructors implicity declared? Why is array constexpr but vector isn't, and what is aggregate-initialization? Understanding Array requires a strong comprehension of these often over-looked language features.

vector

Everyone knows std::vector right? But why is reserving so important? And what is std::allocator and why wrap it in std::allocator_traits?

valarray

valarray provides an introduction to expression-templates. It stores elements in a vector, and it provides element-wise unary and binary operations. It won't create any temporaries and will only perform one iteration as it evaluates the expression for each resultant element.

Memory Mangement

unique_ptr

unique_ptr is pretty simple, but its always good to understand what std::default_deleter does and how dangerous aggregate initialisation can be

addressof

addressof might seem like a verbose way of calling &T; but why does it exist? And why is it constexpr in C++17 and what does a constexpr pointer mean?

allocator

allocator is relatively simple, but why does it define is_always_equal and propagate_on_container_move_assignment.