Logtalk reference manual
Built-in method: once/1
once/1
Description
once(Goal)
This predicate behaves as call(Goal)
but it is not re-executable. This built-in meta-predicate is declared as a private method and thus cannot be used as a message to an object.
Template and modes
once(+callable)
Errors
- Goal is a variable:
instantiation_error
- Goal is neither a variable nor a callable term:
type_error(callable, Goal)
Examples
- Call a goal deterministically in the context of the object or category containing the call:
once(Goal)
- To send a goal as a non-backtracable message to self:
once(::Goal)
- To send a goal as a non-backtracable message to an explicit object:
once(Object::Goal)
See also
call/1-N
, ignore/1
, \+/1