[ Advanced Control and Suspensions | The ECLiPSe Built-In Predicates | Reference Manual | Alphabetic Index ]
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.
Fail Conditions
None.
Resatisfiable
No.
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