Global Variable Manual Page

This manual describes features contained within the GV prolog knoledge base, and how to use them.

declare(Variable, Value)

Binds a value to a variable globally when called
Arguments:
Example - Bind 5 to a variable with label "a":

?- declare(a, 5). true.

display_bindings

Displays all current bindings
Example - declare variables "a" and "b" and display:

?- declare(a, 5). true. ?- declare(b, 7). true. ?- display_bindings. a -> 5 b -> 7 true.

value_of(Variable, Value)

Gets a value from a global variable
Arguments:
Example - Get value of variable "a":

?- declare(a, 5). true. ?- value_of(a, Value). Value = 5.

bind(Variable, Value)

Rebinds a value to a global variable
Arguments:
Example - Rebind 7 to variable "a" :

?- declare(a, 5). true. ?- bind(a, 7). true.

undeclare(Variable)

Deletes a global variable
Arguments:
Example - delete variable "a" :

?- declare(a, 5). true. ?- undeclare(a). true. ?- display_bindings. true.

inc(Variable)

Increments a global variable
Arguments:
Example - increment variable "a" :

?- declare(a, 5). true. ?- display_bindings. a -> 5 true. ?- inc(a). true. ?- display_bindings. a -> 6 true.

dec(Variable)

Decrements a global variable
Arguments:
Example - decrement variable "a" :

?- declare(a, 5). true. ?- display_bindings. a -> 5 true. ?- dec(a). true. ?- display_bindings. a -> 4 true.

add(Variable, Value)

Adds to a global variable
Arguments:
Example - add 3 to variable "a" :

?- declare(a, 5). true. ?- display_bindings. a -> 5 true. ?- add(a,3). true. ?- display_bindings. a -> 8 true.

sub(Variable, Value)

Subtracts from a global variable
Arguments:
Example - subtract 3 from variable "a" :

?- declare(a, 5). true. ?- display_bindings. a -> 5 true. ?- sub(a,3). true. ?- display_bindings. a -> 2 true.