SWI-Prolog -- autoload/2

Documentation
- Reference manual
  - Modules
    - Controlled autoloading for modules
      - autoload/1
      - autoload/2
- Packages

Availability:built-in

autoload(:File)

autoload(:File, +Imports)

Declare that possibly missing predicates in the module in which this declaration occurs are to be resolved by using use_module/2 on File to (possibly) load the file and make the target predicate available. The autoload/2 variant is tried before autoload/1. It is not allowed for two autoload/2 declarations to provide the same predicate and it is not allowed to define a predicate provided in this way locally. See also require/1, which allows specifying predicates for autoloading from their default location.

Predicates made available using autoload/2 behave as defined predicates, which implies that any operation on them will perform autoloading if necessary. Notably predicate_property/2, current_predicate/1 and clause/2 are supported.

Currently, neither the existence of File, nor whether it actually exports the given predicates (autoload/2) is verified when the file is loaded. Instead, the declarations are verified when searching for a missing predicate.

If the Prolog flag autoload is set to false, these declarations are interpreted as use_module/[1,2].