# “Modern STL Programming” at C++ On Sea 2021

It’s almost time for C++ On Sea 2021! This three-day all-remote conference runs June 30th through July 2nd, 2021. This year it consists of just a single day of conference presentations, preceded by two days of online “workshops” — long-form half-day, full-day, or two-day classes. One of those two-day classes will be Arthur O’Dwyer on “Modern STL Programming: Algorithms, Containers, Iterators.”

You might be familiar with CppCon’s training model, where you buy a conference ticket and then add on specific pre- and/or post-conference classes á là carte for about $1000 each. In contrast, C++ On Sea 2021 offers a combined conference-and-workshop ticket which entitles you to attend all three days, including any class(es) you like; and the combined ticket price is a shockingly low £600 ($850) for the whole three-day package.

The schedule of talks for the “conference day” has not yet been announced, but judging from past years (2020, 2019), I’d predict that there will be about three tracks of about five talks each. (UPDATE, 2021-05-27: The schedule has been announced as two tracks of five talks each, plus a plenary keynote.)

The schedule of classes and workshops also has not yet been announced (UPDATE: yes it has been) but I can say with confidence that one of the classes you’ll be able to attend will be Arthur O’Dwyer’s “Modern STL Programming: Algorithms, Containers, Iterators.”

This is a new and improved version of the “Classic STL” course I gave online at CppCon 2020. To fit that three-day course into C++ On Sea’s two days, I’ve removed the speculative unit on C++20 and reduced the number of labs from nine to six; but to increase its practical usefulness for industry programmers, I’ve managed to add a unit on smart pointers, including a lab exercise where the student is asked to upgrade a piece of code from raw pointers to the appropriate kind(s) of smart pointers.

If you took “Classic STL” at CppCon 2020, this will be basically the same course; you shouldn’t expect much change. But that’s also good news: If you took the CppCon 2020 course and liked it, here’s your chance to recommend it to your friends and coworkers — for a low low price — and with a bonus unit on smart pointers! Act now!

## Class description

With the arrival of C++20 Ranges, it’s more important than ever to have a solid grasp of classic C++ STL concepts: algorithms, containers, and iterators. We’ll look at the technical considerations that went into the design of the Standard Template Library, and how those considerations have evolved in the two decades between C++98 and C++20.

After motivating the STL’s core concepts of non-owning iterators and half-open ranges, we’ll cover the different kinds of iterators in the STL, and look at the mechanisms by which the STL distinguishes iterator capabilities and the kinds of optimizations that it can perform. We’ll do a deep dive on comparator-based algorithms such as merge and partial_sort. We’ll also cover library iterator types such as move_iterator, insert_iterator, and ostream_iterator; and show the usefulness of classic utility types such as std::reference_wrapper. Students will be asked to write and evaluate their own STL-style algorithms, and practice using std::priority_queue.

On Day 2, we’ll cover the sequence containers and their various semantic guarantees, such as contiguity or iterator-stability. Then we’ll cover the associative containers, including the unordered containers. We’ll present best practices for using the standard containers with user-defined comparators and hashers. We’ll also cover the “particular skills” of various containers, such as how std::list::sort differs from std::sort.

The course is bookended by units on two C++ library facilities that are not “classic STL” but are critically important for any programmer: string_view and the smart pointers.

The course is organized as lectures interleaved with six hands-on lab exercises. The lab exercises require a C++14-or-later compiler and either make or nmake.

### Prerequisites

Attendees should have basic to intermediate knowledge of C++11, including at least one year of programming experience. This course focuses on the library, not the language; it’s assumed you will be able to keep up with offhand mentions of language concepts such as “class template,” “rvalue reference,” and “lambda.”

No special knowledge of C++14, C++17, or C++20 is required.

### Course outline

Day 1

• string and string_view (+ lab)
• iterators and the notion of an algorithm (+ lab)
• standard algorithms: sorting, heaps, comparators (+ lab)
• iterator adaptors and output iterators

Day 2

• proxy types, std::ref, std::pair
• sequence containers, iterator invalidation (+ lab)
• associative and unordered containers (+ lab)
• upgrading to smart pointers (+ lab)

### Informational email

It’s still too early to fill in all the blanks on the pre-class informational email you’ll get when you sign up; but for an example of the kind of thing you should expect, see “Classic STL at CppCon 2020” (2020-09-12).

Posted 2021-05-17