度量代码特征的常见度量元

度量元体系

对于已有度量元的分类可以按照提取的角度进行分类也可以从软件质量的角度进行分类。

度量元按照提取方式的角度分为如下的几类

从软件可维护性质量模型的角度可以按照如下的方式进行分类

CK度量元

wmc	Weighted methods per class	CK	类中方法的个数
dit	Depth of Inheritance Tree	CK	类的继承层次
noc	Number of Children	CK	类的直接子类个数
cbo	Coupling between object classes	CK	类与其他类存在耦合关系的数量，这里耦合关系只考虑非继承关系，即 CK 认为耦合关系不包括继承关系，只包括依赖 关系、实现关系、关联关系、组合关系、聚合关系。
rfc	Response for a class	CK	类的响应集，RFC一方面反应了类本身定义的方法数量，另一方面反映了一个类与其他类之间的交互性（耦合性）。因此 RFC 体现了类的复杂性。
lcom	Lack of cohesion in methods	CK	内聚缺乏度；计算所有的方法对的个数减去方法对中没有共享全局变量的方法对
ca	Afferent couplings	CK	传入耦合：有多少类依赖于要度量的类
ce	Efferent couplings	CK	传出耦合：要度量的类依赖多少外部类
npm	Number of Methods	CK	有多少方法是公共的方法
lcom3	Lack of cohesion in methods	CK
loc	Lines of Code	CK	代码行数
dam	Data Access Metric	CK	一个类中私有的属性占所有属性的比例
moa	Measure of Aggregation	CK	类中的属性类型是类的定义的个数
mfa	Measure of Functional Abstraction	CK	一个类中继承的方法个数占所有方法个数的比率
cam	Cohesion Among Methods of Class	CK	每个方法不同参数类型总和除以类中不同参数的个数乘以总的方法个数
cbm	Coupling between Methods	CK	继承的方法与该类中新建的方法之间耦合的个数；继承的方法使用新定义的属性，继承的方法调用新建的方法；新建的方法调用继承的方法

McCabe

loc	line of code	McCabe	代码行数
v(g)	cyclomatic complexity	McCabe	圈复杂度
ev(g)	essential complexity	McCabe	基本复杂度

Halstead

n	total oeprators+operands	Halstead	所有的操作符和操作数的和
v	volume	Halstead	程序容量
l	program length	Halstead	程序长度
d	difficulty	Halstead	复杂度
i	intelligence	Halstead	智力
e	effot	Halstead	工作量
t	time estimator	Halstead	时间评估
lOCode	line count	Halstead	代码行数（有效代码）
lOComment	count of lines of comments	Halstead	注释行数
IOBlank	count of blank lines	Halstead	空行数
uniq_Op	unique operators	Halstead	多少种操作操作符
uniq_Opnd	unique operands	Halstead	多少种操作数
total_Op	total operators	Halstead	操作符个数
total_Opnd	total operands	Halstead	操作数个数
branchCount	branch of the flow graph		分支个数
HALSTEAD_LEVEL	level at which the program can be understand	Halstead	程序可以理解的程度

LOC

空白行

注释行

总的代码行

可执行的代码行

code churn

Total LOC	is the number of lines of non-commented executable lines in the files comprising the new version of a binary.
Churned LOC	is the sum of the added and changed lines of code between a baseline version and a new version of the files comprising a binary.
Deleted LOC	is the number of lines of code deleted between the baseline version and the new version of a binary. The churned LOC and the deleted LOC are computed by the version control systems using a file comparison utility like diff.
File count	is the number of files compiled to create a binary.
Weeks of churn	is the cumulative time that a file was opened for editing from the version control system.
File churned	is the number of files within the binary that churned.
churned LOC/Total LOC
Deleted LOC/Total LOC
Weeks of churn/File count
Churned LOC/Deleted LOC

耦合和内聚度量元

CBO	Coupling between object classes. According to the definition of this measure, a class is coupled to another, if methods of one class use methods or attributes of the other, or vice versa. CBO is then defined as the number of other classes to which a class is coupled.
CBO'	Same as CBO, except that inheritance-based coupling is not counted.
DAC	Data abstraction coupling. The number of attributes in a class that have another class as their type.
LCOM1	Lack of cohesion in methods. The number of pairs of methods in the class using no attribute in common.
LCOM2	LCOM2 is the number of pairs of methods in the class using no attributes in common, minus the number of pairs of methods that do. If this difference is negative, however, LCOM2 is set to zero.
LCOM3	Consider an undirected graph G, where the vertices are the methods of a class, and there is an edge between two vertices if the corresponding methods use at least an attribute in common. LCOM3 is defined as the number of connected components of G.
LCOM4	Like LCOM3, where graph G additionally has an edge between vertices representing methods m and n, if m invokes n or vice versa.
LCOM5	Consider a set of methods {Mi} (i=1,...,m) accessing a set of attributes {Aj} (j=1,...,a). Let (Aj) be the number of methods which reference attribute Aj. Then LCOM5=

NetworkMetrics

通过网络嵌入的方式提取模块依赖图中的节点特征

Previous Defects

模块之前含有的缺陷个数

Entropy Metrics

the idea consists in measuring, over a time interval, how distributed changes are in a system.The more spread, the higher is the complexity.

HCM	History of Complexity Metric
WHCM	Weight History of Complexity Metric	cij = pj , each modified file gets the entropy of the system weighted with the probability of the file being modified.