.. index:: single: coupling_metric .. _coupling_metric/0:

.. rst-class:: right

object

coupling_metric

Computes entity efferent coupling, afferent coupling, instability, abstractness, and distance from the main sequence.

| Availability: | logtalk_load(code_metrics(loader))

| Author: Ebrahim Azarisooreh and Paulo Moura | Version: 0:15:0 | Date: 2026-03-13

| Compilation flags: | static, context_switching_calls

| Imports: | public :ref:`code_metrics_utilities <code_metrics_utilities/0>` | public :ref:`code_metric <code_metric/0>` | Uses: | :ref:`list <list/0>`

| Remarks:

• Efferent coupling (Ce): Number of entities that an entity depends on.
• Afferent coupling (Ca): Number of entities that depend on an entity.
• Instability (I): Computed as Ce / (Ce + Ca). Measures the entity resilience to change. Ranging from 0 to 1, with 0 indicating a maximally stable entity and 1 indicating a maximally unstable entity. Ideally, an entity is either maximally stable or maximally unstable.
• Abstractness (A): Computed as the ratio between the number of static predicates with scope directives without a local definition and the number of static predicates with scope directives. Measures the rigidity of an entity. Ranging from 0 to 1, with 0 indicating a fully concrete entity and 1 indicating a fully abstract entity.
• Distance from main sequence (D): Computed as abs(A + I - 1). Measures how far an entity is from the idealized line A + I = 1. Ranging from 0 to 1, with 0 indicating the entity is on the main sequence and 1 indicating it is as far as possible (either maximally abstract and stable, or maximally concrete and unstable).
• Entity score: Represented as the compound term ce_ca_i_a_d(Ce,Ca,I,A,D).
• Dependencies count: Includes direct entity relations plus calls or dynamic updates to predicates in external objects or categories.

| Inherited public predicates: |  :ref:`code_metric/0::all/0`  :ref:`code_metric/0::all/1`  :ref:`code_metric/0::all_score/1`  :ref:`options_protocol/0::check_option/1`  :ref:`options_protocol/0::check_options/1`  :ref:`options_protocol/0::default_option/1`  :ref:`options_protocol/0::default_options/1`  :ref:`code_metric/0::directory/1`  :ref:`code_metric/0::directory/2`  :ref:`code_metric/0::directory_score/2`  :ref:`code_metric/0::entity/1`  :ref:`code_metric/0::entity_score/2`  :ref:`code_metric/0::file/1`  :ref:`code_metric/0::file/2`  :ref:`code_metric/0::file_score/2`  :ref:`code_metric/0::format_entity_score//2`  :ref:`code_metric/0::library/1`  :ref:`code_metric/0::library/2`  :ref:`code_metric/0::library_score/2`  :ref:`options_protocol/0::option/2`  :ref:`options_protocol/0::option/3`  :ref:`code_metric/0::rdirectory/1`  :ref:`code_metric/0::rdirectory/2`  :ref:`code_metric/0::rdirectory_score/2`  :ref:`code_metric/0::rlibrary/1`  :ref:`code_metric/0::rlibrary/2`  :ref:`code_metric/0::rlibrary_score/2`  :ref:`options_protocol/0::valid_option/1`  :ref:`options_protocol/0::valid_options/1`  

.. contents:: :local: :backlinks: top

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)