Conditionally decide which steps should be run at runtime.

Options

• matches - a list of match consisting of predicates and a list of steps to execute if the predicate returns a truthy value. See t:matches for more information. Required.
• default - a list of steps to execute if none of the predicates match. Optional.
• allow_async? - a boolean indicating whether to allow the steps to be executed asynchronously. Optional. Defaults to true.
• on - the name of the argument to pass into the predicates. If this argument is not provided to this step, then an error will be returned.

Branching behaviour

Each of the predicates in matches are tried in order, until either one returns a truthy value, or all the matches are exhausted.

If there is a match, then the matching steps are emitted into the parent running Reactor.

In the case that no match is found, then the steps provided in the default option are emitted. If no default is provided, then an error is returned.

Tip

Execution of predicates stops once the first match is found. This means that if multiple predicates potentially match, the subsequent ones will never be called.

Returning

By default the step returns nil as it's result.

You can have the step return the result of a branch by adding a step to the branch with the same name as the switch which returns the expected value. This will be handled by normal Reactor step emission rules.