Chidamber & Kemerer

Shyam Chidamber and Chris Kemerer proposed a suite of six object-oriented design metrics in their 1994 paper "A Metrics Suite for Object Oriented Design" [1], covering complexity, inheritance, coupling, and cohesion at the class level.

Chidamber & Kemerer Metrics¶

Notes:

1. Chidamber & Kemerer's original WMC definition weights each method by a complexity metric of the implementer's choosing, without specifying one. Understand offers two interpretations: CountDeclMethod counts methods unweighted (every method has weight 1), while SumCyclomatic weights each method by its own Cyclomatic Complexity before summing, which is the more common weighting used in practice.
2. CountDeclMethodAll is also tagged as Lorenz & Kidd's Number of Methods (NM), since RFC's simplified form (methods in the class, ignoring the methods it calls elsewhere) and Lorenz & Kidd's NM count the same thing.
3. PercentLackOfCohesion also goes by LCOM2 — a normalized, percentage-based cohesion formula commonly used in tools (100% minus the average share of methods that touch each attribute). That is not Chidamber & Kemerer's own LCOM from their 1994 TSE paper, which instead counts dissimilar method pairs minus similar method pairs (floored at zero) — a raw integer, not a percentage; Understand uses the LCOM2 form for the suite's cohesion slot.

References¶

1. Chidamber, Shyam R., and Chris F. Kemerer. "A Metrics Suite for Object Oriented Design." IEEE Transactions on Software Engineering, vol. 20, no. 6, 1994, pp. 476-493.

Chidamber & Kemerer Plugins¶