There are two ways to specify dependencies between packages. In order of “general use”:

• list them in the package’s manifest.xml
• add them in the package set’s autobuild scripts

Moreover, a dependency can either be mandatory or optional.

In the first case, autoproj will always refuse to build a package if one of its dependencies is either not defined or excluded from the build

In the second case, autoproj will only take into account the dependency information for building, and simply ignore the dependency if the depended-upon package is inexistent or excluded from the build.

The rest of this page details how to add these two types of dependencies

When to make a dependency optional

This is a matter of engineering, really. Concrete examples are:

• libraries that contain both core functionality and GUIs. GUIs won’t get built on the embedded systems (a.k.a. “robots”), and therefore should be made optional
• dependencies on “heavy” stuff, when the functionality that depends on these heavy packages is not the main package functionality.

Dependencies in the package’s manifest.xml

This should be the main way through which you specify dependencies

The manifest.xml file is a file that lies in each package’s root directory. It contains general information (description, author, license, …) and build related information

The tag can be used to specify dependencies between packages. For instance, to add a dependency on the “drivers/xsens_imu” package, one does

<depend name="drivers/xsens_imu" />

Making a dependency optional is simply a matter of adding the optional=”1” flag:

<depend name="drivers/xsens_imu" optional="1" />

Dependencies in autobuild files

It is useful when some dependencies should be added or not depending on some [configuration options](creating_pkg_set.html#configopts}

This is simply a matter of calling #depends_on(package_name) or #optional_dependency(package_name) on the package objects.

For instance, when defining a new package

cmake_package 'drivers/orogen/pkgname' do |pkg|
  if user_config('WITH_GUI')
    pkg.depends_on 'gui'
  end
end

Or later in for instance autoproj/overrides.rb

if user_config('WITH_GUI')
  package('drivers/orogen/pkgname').depends_on 'gui'
end