Conditions

Every configuration can make use of a condition mechanism to conditionally add parameters.

task = project.program(name='hello-conditions',
                       source=['src'])
task.when(osystem="windows", includes=['src/windows'])
task.when(osystem="linux", includes=['src/linux'])
task.when(osystem="osx", includes=['src/macos'])

project.program() returns a task, which is in fact a definition to build a program, and since it’s a program it also is a configuration, therefore it can make use of the condition mechanism .when(). Here is how it works:

def when(self,
         variant=None,
         link=None,
         runtime=None,
         osystem=None,
         arch=None,
         compiler=None,
         distribution=None,
         release=None,
         <any configuration parameter>)

The when() function takes a list of parameters to express when certain configuration parameters should be applied.

In other words, these condition parameters have to match the options they refer to (e.g. golem configure options) to allow the associated configuration parameters to be applied to what is currently being built.

Here is a description of these condition parameters:

💡 Tip

All the list parameters can be set with single values, Golem makes them lists automatically if they are not.

• variant list of variants (e.g. 'debug', 'release')

• link list of linking options (e.g. 'shared', 'static')

• runtime list of runtime linking options (e.g. 'shared', 'static')

• arch list of architectures (e.g. 'x86', x64)

• compiler list of compilers (e.g. 'msvc', 'gcc', 'clang')

• osystem list of platforms (e.g. 'windows', 'osx', 'linux')

• distribution list of Linux distributions (e.g. 'debian')

• release list of Linux distribution releases (e.g. 'trixie'), requires lsb_release Python module

In our previous example, task.when(osystem="windows", includes=['src/windows']) adds 'src/windows' to the includes parameter of the task only if the current platform is Windows.

Examples#

To learn with examples have a look at:

• https://github.com/GolemCpp/golem/tree/main/examples/conditions