How to elicit an instalation on a client



I’m using Plots (GR backend) to create some animations. At least on osx, Plots needs cairo and ffmpeg installed for animations to work. While I can “fix” that for the CI by adding this line to the .travis.yml file:

  - if [[ "$TRAVIS_OS_NAME" == "osx" ]]; then brew install ffmpeg cairo; fi

it doesn’t take care of the fact that users that will use my package will have to manually install cairo and ffmpeg. Is there any other elegant way to solve this other than stating exactly that in the README?