Interlude 1. Smells and Refactorings


The smells (along with the refactorings commonly used to fix them) from Martin Fowler's book Refactoring are listed in Table I-1, and the refactorings are listed in Table I-2.

INTERLUDE I1.1

Tally. Put a tally mark by each refactoring for each time a smell references it.

INTERLUDE I1.2

Refactorings that Fix the Most Smells. Which refactorings fix the most smells?

See Appendix A for solution.

INTERLUDE I1.3

Refactorings Not Mentioned. Which refactorings aren't mentioned by any of the smells? Why not?

See Appendix A for solutions.

INTERLUDE I1.4

Other Smells. Does this list suggest any other smells you might want to be aware of?

See Appendix A for solutions.


Table I.1. Smells and Their Associated Refactorings (from Fowler's Refactoring , back cover)

SMELL

COMMON REFACTORINGS

Alternative Classes with Different Interfaces

Rename Method, Move Method

Comments

Extract Method, Introduce Assertion

Data Class

Move Method, Encapsulate Field, Encapsulate Collection

Data Clump

Extract Class, Introduc 6 e Parameter Object, Preserve Whole Object

Divergent Change

Extract Class

Duplicated Code

Extract Method, Extract Class, Pull Up Method, Form Template Method

Feature Envy

Move Method, Move Field, Extract Method

Inappropriate Intimacy

Move Method, Move Field, Change Bidirectional Association to Unidirectional, Replace Inheritance with Delegation, Hide Delegate

Incomplete Library Class

Introduce Foreign Method, Introduce Local Extension

Large Class

Extract Class, Extract Subclass, Extract Interface, Replace Data Value with Object

Lazy Class

Inline Class, Collapse Hierarchy

Long Method

Extract Method, Replace Temp with Query, Replace Method with Method Object, Decompose Conditional

Long Parameter List

Replace Parameter with Method, Introduce Parameter Object, Preserve Whole Object

Message Chains

Hide Delegate

Middle Man

Remove Middle Man, Inline Method, Replace Delegation with Inheritance

Parallel Inheritance Hierarchies

Move Method, Move Field

Primitive Obsession

Replace Data Value with Object, Extract Class, Introduce Parameter Object, Replace Array with Object, Replace Type Code with Class, Replace Type Code with Subclasses, Replace Type Code with State/Strategy

Refused Bequest

Replace Inheritance with Delegation

Shotgun Surgery

Move Method, Move Field, Inline Class

Speculative Generality

Collapse Hierarchy, Inline Class, Remove Parameter, Rename Method

Switch Statements

Replace Conditional with Polymorphism, Replace Type Code with Subclasses, Replace Type Code with State/Strategy, Replace Parameter with Explicit Methods, Introduce Null Object

Temporary Field

Extract Class, Introduce Null Object

Table I.2. Refactorings (from Fowler, Refactoring , inside front cover)

Add Parameter

Pull Up Constructor Body

Change Bidirectional Association to Unidirectional

Pull Up Field

Change Reference to Value

Pull Up Method

Change Unidirectional Association to Bidirectional

Push Down Field

Change Value to Reference

Push Down Method

Collapse Hierarchy

Remove Assignment to Parameters

Consolidate Conditional Expression

Remove Control Flag

Consolidate Duplicate Conditional Expression

Remove Middle Man

Convert Procedural Design to Objects

Remove Parameter

Decompose Conditional

Remove Setting Method

Duplicate Observed Data

Rename Method

Encapsulate Collection

Replace Array with Object

Encapsulate Downcast

Replace Conditional with Polymorphism

Encapsulate Field

Replace Constructor with Factory Method

Extract Class

Replace Data Value with Object

Extract Hierarchy

Replace Delegation with Inheritance

Extract Interface

Replace Error Code with Exception

Extract Method

Replace Exception with Test

Extract Subclass

Replace Inheritance with Delegation

Extract Superclass

Replace Magic Number with Symbolic Constant

Form Template Method

Replace Method with Method Object

Hide Delegate

Replace Nested Conditional with Guard Clause

Hide Method

Replace Parameter with Explicit Methods

Inline Class

Replace Parameter with Method

Inline Method

Replace Record with Data Class

Inline Temp

Replace Subclass with Fields

Introduce Assertion

Replace Temp with Query

Introduce Explaining Variable

Replace Type Code with Class

Introduce Foreign Method

Replace Type Code with State/Strategy

Introduce Local Extension

Replace Type Code with Subclasses

Introduce Null Object

Self Encapsulate Field

Introduce Parameter Object

Separate Domain from Presentation

Move Field

Split Temporary Variable

Move Method

Substitute Algorithm

Parameterize Method

Tease Apart Inheritance

Preserve Whole Object

 


Refactoring Workbook
Refactoring Workbook
ISBN: 0321109295
EAN: 2147483647
Year: 2003
Pages: 146

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