Abseil Blog

Abseil Random

21 Nov 2019

By Andy Soffer, Engineer

We are happy to announce the arrival of the Abseil Random library, providing simple tools for generating random numbers and testing code that uses random numbers.

Abseil now includes a random number generation library, which can be found in absl/random/. The library includes

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Introducing Abseil Options

15 Nov 2019

By Greg Falcon, Abseil Engineer

Abseil now provides an options file, providing a limited means of configuring Abseil’s features. In the initial release of this options mechanism, we have added the ability to override Abseil’s automatic type detection and force (for example) absl::string_view to either always alias to std::string_view, or always remain using our Abseil implementation.

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B-tree Ordered Containers

12 Aug 2019

By Evan Brown, Engineer

The Abseil container library now includes B-tree containers that generally conform to the STL sorted container APIs:

• absl::btree_set (meant to replace usage of std::set)
• absl::btree_map (meant to replace usage of std::map)
• absl::btree_multiset (meant to replace usage of std::multiset)
• absl::btree_multimap (meant to replace usage of std::multimap)

You use a B-tree container just as you would an STL ordered container:

#include "absl/container/btree_map.h"

absl::btree_map<int, std::string> ducks =
    {{2, "dewey"}, {1, "huey"}, {3, "louie"},};

// Prints "huey, dewey, louie "
for (const auto& n : ducks) {
    std::cout << n.second << ", ";
}

B-trees have a different implementation from STL std::map containers, which require binary trees commonly implemented as red-black trees. While a red-black tree is limited to single-element nodes, with precisely two children, a B-tree may contain multiple values per node (M), with each node having (M+1) children. Having more values and children per node is more cache friendly because nodes are generally allocated separately so accessing additional nodes often results in cache misses.

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Abseil Flags

09 May 2019

By Gennadiy Rozental, Abseil Engineer

Abseil is very happy to announce the release of the Abseil Flags library. Abseil’s flags library provides a standard, readable way to pass command-line values to a program.

#include <iostream>
#include <string>

#include "absl/flags/flag.h"
#include "absl/flags/parse.h"

ABSL_FLAG(std::string, name, "you", "Name of the person to greet");

int main(int argc, char** argv) {
  absl::ParseCommandLine(argc, argv);
  std::cout << "Hello " << absl::GetFlag(FLAGS_name) << "!" << std::endl;
  return 0;
}

$ greet
Hello you!
$ greet --name=Alice
Hello Alice!

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Abseil Support for CMake

02 Apr 2019

By Jon Cohen, Abseil Engineer

CMake is a popular tool used to build multi-platform C++ projects. Abseil has had unofficial CMake support for some time, but support has never been as robust as that for Bazel. We are happy to announce that Abseil now fully supports the CMake build system.

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