8. dhaval.dalal@software-artisan.com
Why Should I Refactor?
! Development is a process of Discovery
and code constantly evolves.
! Refactoring is a code curative
technique, just as Sleep is a Curative
Agency for the body playing part in
repairing mechanism of the body.
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9. dhaval.dalal@software-artisan.com
Why Should I Refactor?
Any fool can write code that a computer
can understand. Good programmers write
code that humans can understand. The
purpose of refactoring is to make the
software easier to understand and modify.
Martin Fowler.
10. dhaval.dalal@software-artisan.com
Why Should I Refactor?
! It improves the design of software
" By repairing a highly coupled, non-cohesive
design.
! Helps to find bugs faster.
! Helps to Program Faster.
11. dhaval.dalal@software-artisan.com
Code Smells…lets code along
! Duplicate Code
! Switch Statements
! Long Method
! Long Parameter List
! Large Class
! Indecent Exposure
! Divergent Change
! Shotgun Surgery
! ...and many more.
If it Stinks,
Change it!
! Speculative Generality Kent Beck
12. dhaval.dalal@software-artisan.com
Deodorize With Fresheners…code along
! Encapsulate Collections
! Encapsulate Downcast
! Replace Error Code with Exception
! Introduce Variable
! Introduce Symbolic Constants
! Rename Method/Variable
! Remove Control Flag
! Simplify Conditionals
! Simply Nested Conditionals with Guard Clauses
! Move Method
! Chain Multiple Constructors/Methods
! Replace Type Code with Enums or Class
14. dhaval.dalal@software-artisan.com
General Principles in Refactoring
! From Near to Far.
" That which is obvious and close to us now
is the starting point, a.k.a the inflection
point.
" That which is abstract is the goal.
! Take baby-steps.
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16. dhaval.dalal@software-artisan.com
Undertaking Big Refactorings
(Bridge Replacement Metaphor)
! Let traffic continue to
flow on old bridge.
! Create new refactored
implementation.
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! Create another bridge
side-by-side the old one.
! Take an Interface-oriented
approach.
! House the old code in
one implementation.
! When the new bridge is
ready, delink traffic from
the old one and re-route it
over the new bridge.
! Use the new impl. by
replacing the old one.
17. dhaval.dalal@software-artisan.com
Refactoring To Patterns
! Arrive to pattern via series of small
refactorings.
" Rigorously apply OO principles along-side
continuous refactoring.
# SRP, OCP, LSP, ISP, DIP (SOLID) etc...
" You will eventually evolve to some known
pattern.
! When you “intuit” that a pattern will
readily apply.
" Approach this in baby steps. 14
18. dhaval.dalal@software-artisan.com
Refactoring and Legacy Code
! Code without tests is Legacy.
" Does anyone still create this?
" Michael Feathers’ has an excellent book on
this.
#Working Effectively with Legacy Code
! Refactoring code without tests is like
performing a tight-rope walk without any
safety net underneath.
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20. dhaval.dalal@software-artisan.com
As in many things the answer lies in
balancing opposing forces,
especially when its difficult to make
hidden Business Value explicit.
Pragmatic Vs Dogmatic
Agility Vs Fragility
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When to Refactor?
21. dhaval.dalal@software-artisan.com Views on Refactoring
! A traditionalist view on Refactoring is
re-work!
! In reality, it is responding to new
information as it arrives.
! At the same time, avoid “Major
Refactorings”
" Do initial architecture envisioning.
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22. dhaval.dalal@software-artisan.com
No Silver Bullet
Refactoring is no “silver bullet”, yet it is
a valuable tool, a pair of silver pliers
that helps you keep good grip on your
code. Without refactoring, the design
of the program will decay.
Martin Fowler
23. dhaval.dalal@software-artisan.com
References
! Refactoring
" Martin Fowler.
! Refactoring to Patterns
" Joshua Kerievsky.
! Refactoring Motivations
" Jay Fields’ Blog
! Creating an Agile Culture to drive organizational Change
" David Anderson
