Modularity

Question 1

what is module

Answer 1

each of the set of standardized parts that are used to create more complex structure

Question 2

how is modularity being measured

Answer 2

by using three factors - cohesion, coupling and connascence

Question 3

what is cohesion

Answer 3

cohesion is an indication of the extent to which parts of a module should be kept together, inside the module

Question 4

what is coupling

Answer 4

coupling is an indicator of how much calls a module needs to make to another module so as to be able to perform any meaningful transaction

Question 5

what are the varieties of cohesion

Answer 5

functional (best), sequential, communicational, procedural, temporal, logical, coincidental (worst)

Question 6

what is LCOM measure of cohesion

Answer 6

LCOM or Lack of Cohesion Measurement is a part of Chidamber and Kemerer suit of Object - oriented metrics. It represents the sum of the methods not shared via sharing of a common field; so for example, in a class if there are 3 out 10 methods that shares common attribute, would have lower LCOM score (and therefore less cohesion, which is usually bad) than the class that has 7 out of 10 methods that uses the shared common attribute.

Question 7

what is afferent coupling

Answer 7

number of inbound calls

Question 8

what is efferent coupling

Answer 8

number of outbound calls

Question 9

what is abstractness

Answer 9

the ratio between number of abstract methods to concrete method is the measure of abstractness

Question 10

what is instability

Answer 10

the ratio between efferent coupling / sum of afferent & efferent coupling; higher value indicates that there are lot of outbound calls that a class makes, thereby making it susceptible to breakage in case any of the called classes break

Question 11

what is distance from main sequence

Answer 11

distance from main sequence = |abstractness + instability - 1|; if abstraction scores high, a class falls to zone of uselessness, if instability is very high then the class falls to zone of pain

Question 12

what is connascence

Answer 12

two components are connascent if change in one, requires changing in the other, to ensure that the system functions correctly

Question 13

what is the difference between static and dynamic connascence

Answer 13

static connascence indicates source code level coupling and dynamic connascence indicate runtime coupling

Question 14

what are the variety of static connascence

Answer 14

static connascence indicates the degree to which multiple components agree on the name, type, meaning, position, algorithm of a given entity

Question 15

what is the use of connascence as a tool

Answer 15

connascence is a measure that needs to be minimized across module boundaries, by the use of encapsulation; the connascence within a module should be made high

Question 16

what are 7 typical code review sections

Answer 16

Style, Correctness, Complexity, Design, Security & Coverage

Question 17

what are to be used for consistent styling

Answer 17

checkstyle & .editorconfig

Question 18

what are to be used to ensure code correctness

Answer 18

spotbugs, pmd, checker, error prone etc. can find potential coding issues

Question 19

what is used to measure code complexity

Answer 19

code complexity are of two types, cyclometric complexity, which if higher makes testing more difficult and cognitive complexity, which if higher makes understanding code more difficult

Question 20

what is used to find design flaws

Answer 20

checkstyle, pmd validates design issues with class, method, parameter and source code level design issues

Question 21

what is the way to find security vulnerability

Answer 21

using findsecbugs and sonarquebe

Question 22

how to measure code coverage

Answer 22

by using Jacoco

Question 23

what are some advanced mechanism to find design flaws

Answer 23

PMD’s LawOfDemeter — Law of Demeter is a simple rule that can help in reducing tight coupling between classes.

Checkstyle’s DesignForExtension — based on Effective Java 3rd Edition book by Joshua Bloch, Item 17: Design and document for inheritance or else prohibit it.

PMD’s CouplingBetweenObjects — detects tightly coupled classes that are difficult to test, analyze and extend by measuring its number of unique attributes, local variables and return types.

jPeek — you can use this tool to measure the cohesion of our classes and as a result, help to keep the high cohesion of classes, modules, packages.