zenofgithub - how to consume portable conan.io C/C++ packages, like libzengithub, libgit2 and libcurl and build on multiple platforms

zenofgithub is a small C application that prints out a random Zen of Github whenever you call it from a directory that contains a Git repository:

./zenofgithub

will provide you something like

               MMM.           .MMM
               MMMMMMMMMMMMMMMMMMM
               MMMMMMMMMMMMMMMMMMM      _________________________________________
              MMMMMMMMMMMMMMMMMMMMM    |                                         |
             MMMMMMMMMMMMMMMMMMMMMMM   | Anything added dilutes everything else. |
            MMMMMMMMMMMMMMMMMMMMMMMM   |_   _____________________________________|
            MMMM::- -:::::::- -::MMMM    |/
             MM~:~ 00~:::::~ 00~:~MM
        .. MMMMM::.00:::+:::.00::MMMMM ..
              .MM::::: ._. :::::MM.
                 MMMM;:::::;MMMM
          -MM        MMMMMMM
          ^  M+     MMMMMMMMM
              MMMMMMM MM MM MM
                   MM MM MM MM
                   MM MM MM MM
                .~~MM~MM~MM~MM~~.
             ~~~~MM:~MM~~~MM~:MM~~~~
            ~~~~~~==~==~~~==~==~~~~~~
             ~~~~~~==~==~==~==~~~~~~
                 :~==~==~==~==~~

if you are in a Git repo and

You're not in a git repo so the octocat will stay silent.
Create a git repo and the Zen of GitHub will be revealed to you.

if you are not in a Git repo.

But why?

The main purpose of this application is to demo how you can use the portable conan.io package manager to declare (and easily consume) C/C++ dependencies no matter whether you are running on Windows, Linux or Mac.

This small demo application consumes a lot of packages, like ZenGithub, libgit2, libbzip2 and their transitive dependencies:

conan info . --graph deps.html
open deps.html

The only thing to consume all those dependencies is to have a conanfile.txt which is referencing the versions you want:

[requires]
ZenGitHub/1.0@jonico/stable
libgit2/0.26.0@jonico/stable

conan.io takes care of the rest, downloads the dependencies from your conan.io remotes and if it cannot find appropriate binaries for your architecture, download the build recipe and build locally.

If you look into conanfile-semver.txt, you can also see an example how you can use semantic versioning while specifying your package dependencies:

[requires]
ZenGitHub/[>0.9<1.2 || 0.8]@jonico/stable # In such range, OR’ing possible
libgit2/[~=0.26.0]@jonico/stable # Compatible according to semantic versioning

Building the package

Basic setup

First, install the conan package manager locally. Then, add the remote to my conan bintray repo where the ZenGithub package is stored:

conan remote add conan-jonico https://jonico.jfrog.io/artifactory/api/conan/libzengithub-conan

Then, clone this repository and cd into it:

git clone https://github.com/jonico/zenofgithub.git && cd zenofgithub

After that, create a build subdirectory and cd into it:

mkdir build && cd build

Installing dependent conan packages

Now you can let conan do the work and install all needed dependencies and generates the files conanbuildinfo.txt and conanbuildinfo.cmake with all the paths and variables that we need to link with our dependencies.

conan install ..

If conan complains about missing dependencies (like ZenGitHub, libCurl or libz or OpenSSL), this is an indication that we do not have a pre-built version of those packages for your architecture. Don't worry, this is how you can build anything missing on your local machine instead:

conan install .. --build missing

If you rather want to link statically against libcurl (or other libraries), run

conan install .. -o libcurl:shared=False --build missing

Generating Makefile, compile and link

Now, that all dependencies are satisfied and conanbuildinfo.txt and conanbuildinfo.cmake are generated, we just have to create the Makefile using cmake (or any other generator of your choice).

For Linux and Mac, run

cmake .. -G "Unix Makefiles" -DCMAKE_BUILD_TYPE=Release
cmake --build .

For Windows, run

cmake .. -G "Visual Studio 14 Win64"
cmake --build . --config Release

After that, you can finally run our small program:

cd bin
./zenofgithub

If the does not reveal a Zen of GitHub yet, you have to switch to a Git repo or create one:

git init
./zenofgithub

               MMM.           .MMM
               MMMMMMMMMMMMMMMMMMM
               MMMMMMMMMMMMMMMMMMM      _______________________________________
              MMMMMMMMMMMMMMMMMMMMM    |                                       |
             MMMMMMMMMMMMMMMMMMMMMMM   | Non-blocking is better than blocking. |
            MMMMMMMMMMMMMMMMMMMMMMMM   |_   ___________________________________|
            MMMM::- -:::::::- -::MMMM    |/
             MM~:~ 00~:::::~ 00~:~MM
        .. MMMMM::.00:::+:::.00::MMMMM ..
              .MM::::: ._. :::::MM.
                 MMMM;:::::;MMMM
          -MM        MMMMMMM
          ^  M+     MMMMMMMMM
              MMMMMMM MM MM MM
                   MM MM MM MM
                   MM MM MM MM
                .~~MM~MM~MM~MM~~.
             ~~~~MM:~MM~~~MM~:MM~~~~
            ~~~~~~==~==~~~==~==~~~~~~
             ~~~~~~==~==~==~==~~~~~~
                 :~==~==~==~==~~

Enjoy ❤️