stl

How to Reorder A Collection With the STL—Jonathan Boccara

Did you know?

How to Reorder A Collection With the STL

by Jonathan Boccara

From the article:

The STL lets you do plenty of things on collections, and one of them is to reorder the elements inside of the collection. Or, said another way, to perform a permutation on the collection.

Inded, moving elements around a collection typically takes a fair amount of complex code to write, involving for loops and iterators. And it is perhaps the area where the STL generates the most spectacular improvements, by encapsulating those complex operations behing meaningful interfaces.

Let’s see what sorts of permutations the STL offers:

  • Lexicographical permutations
  • Cyclic permutations
  • Random permutation
  • Reverse
  • Checking for permutations
  • Other permutations

How to Pass a Polymorphic Object to an STL Algorithm—Jonathan Boccara

Did you ever try?

How to Pass a Polymorphic Object to an STL Algorithm

by Jonathan Boccara

From the article:

As we can read in the opening chapter of Effective C++, C++ is a federation of 4 languages:

  • the procedural part coming from C,
  • the object-oriented part,
  • the STL part (following a functional programming paradigm),
  • the generic part with templates.

And what’s more, all of those 4 sub-languages are part of one whole: the C++ language. Those 4 paradigms begin united in one language gives opportunities for them to interact – and often, those interactions create interesting situations.

Today we’re focusing on one particular interaction, between the object-oriented model and the STL. There could be multiple forms for this interaction, and the case we will look at is how to pass a polymorphic (that is, having virtual methods) function object to an STL algorithm.

How to Use the STL With Legacy Output Collections—Jonathan Boccara

And how back_inserter works.

How to Use the STL With Legacy Output Collections

by Jonathan Boccara

From the article:

When you start using the STL and its algorithms in your code, it’s a bit of a change of habits. And then after a while you get used to it. Then it becomes a second nature. And then even your dreams become organized into beautifully structured ranges that fly in and out of well-oiled algorithms.

And when you reach that point, there is no coming back.

Until the day you come upon an old legacy structure that won’t let itself approached by the elegant and expressive way of coding that STL algorithms have. It’s a terrible encounter, where the beast tries to suck you back into the lengthy and dangerous quicksand of the raw for loops that now seemed so far away...

CppCon 2016: std::accumulate: Exploring an Algorithmic Empire—Ben Deane

Have you registered for CppCon 2017 in September? Don’t delay – Registration is open now.

While we wait for this year’s event, we’re featuring videos of some of the 100+ talks from CppCon 2016 for you to enjoy. Here is today’s feature:

std::accumulate: Exploring an Algorithmic Empire

by Ben Deane

(watch on YouTube) (watch on Channel 9)

Summary of the talk:

What is the most powerful algorithm in the STL? In the world? There are many cases to be made. But this talk explores what I think is a pretty good candidate, which C++ calls std::accumulate(). Tucked away in <numeric>, perhaps relatively unregarded when compared with workhorses like std::find_if() and std::partition(); nevertheless, std::accumulate() is in some sense the ur-algorithm on sequences.

Let’s explore the result of looking at code through an accumulate-shaped lens, how tweaking the algorithm for better composability can unlock many more uses, and how it can be further genericized with applications to parallelism, tree structures, and heterogeneous sequences.

std::accumulate(): it’s not just for adding things up!

Snail: Continuation-ready algorithms from STL algorithms—Manu Sánchez

Monads in use, finally!!

Snail | Continuation-ready algorithms from STL algorithms

by Manu Sánchez

From the article:

Snail is my try to get a continuation-ready set of algorithms to operate on C++ containers, but instead of reinventing all the algorithms, addapting them through a continuation monad (or something resembling a continuation monad).