object

# `print_goal_hook`

Use this object to easily print entity predicate goals before, after, or before and after calling them.

Author: Paulo Moura
Version: 1:0:0
Date: 2020-03-14
Compilation flags:
`static, context_switching_calls`
Implements:
`public` expanding
Remarks:

> - Usage: Mark a goal to be printed by prefixing it with an operator. Printing uses a `comment` message.

> - To print goal before calling it: `- Goal`.

> - To print goal after calling it: `+ Goal`.

> - To print goal before and after calling it: `* Goal`.

> - Operators: This hook object uses the standard `-` and `+` prefix operators and also defines a global `*` prefix operator with the same type and priority.

Inherited public predicates:
goal_expansion/2 term_expansion/2

## Public predicates

(no local declarations; see entity ancestors if any)

## Protected predicates

(no local declarations; see entity ancestors if any)

## Private predicates

(no local declarations; see entity ancestors if any)

## Operators

(none)

See also

backend_adapter_hook, default_workflow_hook, grammar_rules_hook, identity_hook, prolog_module_hook(Module), object_wrapper_hook, write_to_stream_hook(Stream,Options), write_to_stream_hook(Stream), suppress_goal_hook