sonarsource认知复杂度文档CognitiveComplexity.pdf

Thomas J. McCabe’s Cyclomatic Complexity has long been the de facto standard for

measuring the complexity of a method’s control flow. It was originally intended “to identify

software modules that will be difficult to test or maintain”[1], but while it accurately calculates

the minimum number of test cases required to fully cover a method, it is not a satisfactory

measure of understandability.

This is because methods with equal Cyclomatic Complexity do

not necessarily present equal difficulty to the maintainer, leading to a sense that the

measurement “cries wolf” by over-valuing some structures, while under-valuing others.

a large, easily maintained domain class, or a small class with a complex control flow. Beyond

the class level, it is widely acknowledged that the Cyclomatic Complexity scores of

applications correlate to their lines of

code totals. In other words, Cyclomatic Complexity is of

little use above the method level.

As a remedy for these problems, Cognitive Complexity has been formulated to address

modern language structures, and to produce values that are meaningful at the class and

application levels. More importantly, it departs from the practice of evaluating code based on

mathematical models so that it can yield assessment

s of control flow that correspond to