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 code_metrics_utilities

public code_metric

Uses:

list

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.