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make_suspension(+Goal, +Prio, -Susp, +Module)

Make Goal from module Module a suspended goal with waking priority Prio and return the corresponding suspension object in Susp.
Goal
A Prolog Goal.
Prio
A small integer.
Susp
A variable.
Module
An atom.

Description

The goal Goal from module Module is made a suspended goal, i.e. it enters the suspended part of the resolvent and shows up as a delayed goal. When the debugger is on, a DELAY port is generated.

A suspension can be in three states:

	State		Printed as
	---------------------------------
	sleeping	'SUSP-_123-susp'
	scheduled	'SUSP-_123-sched'
	dead		'SUSP-_123-dead'

The Prio argument determines the priority with which the Goal will be scheduled when woken. It can be a positive number between 1 and 12, or zero, in which case the priority defaults to the priority setting of the predicate which is called in Goal.

Note that a suspension is not a standard Prolog data structure and can only be manipulated in a restricted way. In particular, a suspension is not an atom although it gets printed by default in the form 'SUSP-_123-susp'. The only way to create a suspension is with make_suspension/3,4, suspend/3,4 or by copying an existing suspension. The contents of a suspension can only be retrieved using get_suspension_data/3.

Modes and Determinism

Exceptions

(4) instantiation fault
Goal is not instantiated.
(4) instantiation fault
Module is not instantiated.
(5) type error
Goal is not a callable term.
(5) type error
Susp is not a variable.
(5) type error
Prio is not an integer.
(5) type error
Module is not an atom.
(6) out of range
Prio is not a valid priority.
(60) referring to an undefined procedure
Goal refers to an undefined precedure.

See Also

suspend / 3, insert_suspension / 4, is_suspension / 1, make_suspension / 3, schedule_suspensions / 1, schedule_suspensions / 2, get_suspension_data / 3, wake / 0