intercept

Documentation
- Reference manual
  - The SWI-Prolog library
    - library(intercept): Intercept and signal interface
- Packages

Availability::- use_module(library(intercept)).(can be autoloaded)

intercept_all(+Template, :Goal, ?Ball, -List)

True when List contains all instances of Template that have been sent using send_signal/1 where the argument unifies with Ball. Note that backtracking in Goal resets the List. For example, given

enum(I, Max) :- I =< Max, !, send_signal(emit(I)),
                I2 is I+1, enum(I2, Max).
enum(_, _).

Consider the following queries

?- intercept_all(I, enum(1,6), emit(I), List).
List = [1, 2, 3, 4, 5, 6].

?- intercept_all(I, (between(1,3,Max),enum(1,Max)),
                 emit(I), List).
Max = 1, List = [1] ;
Max = 2, List = [1, 2] ;
Max = 3, List = [1, 2, 3].

See also: nb_intercept_all/4