Anti-patterns

By: Andrei Uvarov
Java developer

© 2016 Return On Intelligence, Inc. All Rights Reserved
Agenda
Introduction
• Definitions
• Reasons to learn
• Root causes
Methodological APs
Coding APs
OOD APs
Software design APs
Project Management APs
Other AP examples

• Questions: end of sections only
Our workflow
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• Discussions: end of training
Our workflow
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Anti-pattern is…
• … a common response to a recurring problem that is usually
ineffective and risks being highly counterproductive.

• Process, solution, actions — obvious, but ineffective
• Alternative solution — working and effective
Anti-pattern includes

• Know your enemy
Goals

• Use common terms
– as with patterns
Goals

• Recognize problem early
Goals

• Don’t “walk on known rakes”
Goals

• Haste
Root causes

• Ignorance
Root causes

• Laziness
Root causes

• Arrogance
Root causes

• Summary:
“I don’t have time and I don’t feel like learning all that crap,
I’ll do without!”
Root causes

• The way we code
Methodological anti-patterns

• The name says it all
– just copy your code fragments
Copy & paste

• Refactoring
– Extract method
– Use IDE tools
Copy & paste — solution

• If all you have is a hammer, everything looks like a nail
– “Law of the instrument”
Golden hammer

• Look at the problem from another point of view
• Look at another technology
• How many patterns do you remember?
Golden hammer — solutions

• Learn more than one tool!
Golden hammer — solutions

• Battle for the performance from start
– Repeat for every line you add
– Sacrifice the design if needed
– No need to measure with performance tests!
Premature optimization

• A simple design is easier to optimize
• Measure your performance
• Optimize worst points first
• Mind the 80-20 rule
Premature optimization — solutions

• Forget about that performance!
– Design is über alles
– Don’t bother caching
– Copy heavyweight containers
– …? (Add your option)
Premature pessimization

Keep the balance!

• Create your own solution for everything
– and be original…
Reinventing the square wheel

• Be aware of existing solutions, libraries etc.
• Don’t be afraid of them
• But be sure you understand them
Reinventing the square wheel — solution

• Copy & paste
• Golden hammer
• Premature optimization
• Premature pessimization
• Reinventing the square wheel
Methodological anti-patterns

Introduction
• definitions
• reasons to learn
• root causes
Methodological APs
Coding APs
OOD APs
Software design APs
Other AP examples
Agenda

• Our everyday “friends”
Coding anti-patterns

• “Tactical” level
– but can affect project in general

• Ongoing improvements
– “Keep your planet clean”
• “Clean code” approach

• Use unexplained numbers in code
• … or even unexplained strings
• … or explained only in javadocs
Magic numbers

• Solution: Replace with constants
– Easier to read
– Easier to change
Magic numbers — solution

• Add MORE complexity to the solution
– essential complexity: we have a hard problem
– accidental complexity: we have made a problem hard
Accidental complexity

• Solution:
– Avoid “tricky code”
– Check yourself
– Keep cleaning your code
Accidental complexity — solution

• Use patterns, technologies, frameworks
without understanding why
• “Full-stackoverflow developer”
Cargo cult programming

• Understand what you are doing
• Learn!
Cargo cult programming — solution

• Guess the problem source
• Don’t use logs, stack traces, local bug reproducing
• Fix the symptoms only
Shot in the dark

Shot in the dark

• Tactical: understand the problem before fixing
• Really fix it – not only cure the symptoms
Shot in the dark – solutions

• Strategical: provide yourself with diagnostic tools
– Use logging
– Keep stacktrace
– Document steps
Shot in the dark – solutions

• Just fix and commit: we have QA anyway, no need for self-testing
• Just use this class: there are hardly any restrictions
Blind faith

• Aviation rule: Don’t assume — check!
Blind faith — solutions

• Don’t remove any code!
You may need it… sometimes… probably…
Boat anchor

• “Is this code working or obsolete?”
Boat anchor — consequences

• “That ancient mess?! We’ll better write a new one!”
Boat anchor — consequences

VCS.
Boat anchor — solution
Just use it.

• Don’t even touch that code!
– It will take time…
– It can affect… something, we don’t even know what!
Lava flow

• Things will get only worse by themselves
Lava flow — consequences

• Write tests before refactoring
– And you will be more confident while cleaning
Lava flow — solutions

• Remember?
Keep. Your. Planet. Clean.
Lava flow — solutions

• Don’t tell user what’s happening
Error hiding
This should be enough.

• Cause: desire to hide complexity
• Solution:
– simplified message for user
– detailed message in log
– show errors depending on environments
Error hiding — solutions

• Just keep adding lines to the method
– Using labels made it even more spicy in olden days
– But you still can do it with IF’s just like that
Spaghetti code

• “Clean code” practices
– E.g.: methods not longer than a screen
• Use metrics to stay warned!
Spaghetti code — solutions

More food!
Ravioli code Lasagna code

• Keep all configuration at hand: have it all in code!
– Usernames, passwords, hosts, paths…
Hard coding

• Properties files
• User input
• External configuration
Hard coding — solutions

• OK, OK, I got it. No more business logic in code!
– Let’s move everything to… database?
Soft coding
There’s definitely something wrong here…

Smart coding!

• Have a special code for every new special case
– Refactoring is for cowards!
Coding by exception

• It is not about try-catch
• New case can be not-so-new
• Adapt your code
Coding by exception — details

• Accidental complexity
• Cargo cult programming
• Shot in the dark
• Blind faith
• Boat anchor
• Lava flow
• Error hiding
• Spaghetti code
• Hard coding
• Soft coding
• Coding by exception

• How to prevent?
Methodological & coding anti-patterns

• Inspections
• Code reviews
• Metrics
• Mind your technical debt!
Methodological & coding anti-patterns

Agenda
Introduction
• definitions
• reasons to learn
• root causes
Methodological APs
Coding APs
OOD APs
Software design APs
Other AP examples

• The way the system is designed
– on classes level
Object-oriented design anti-patterns

• Is circle an ellipse?
Circle-ellipse problem

• No!
…says Liskov’s substitution principle
• Ellipse.stretchX()
– Can not be replaced with Circle!
Circle-ellipse problem

• Return success/failure value; or raise an exception
– OperationNotSupportedException
• Return the new value (no change for Circle)
• Allow for a weaker contract
– stretchX() also calls stretchY() (Surprise!)
• Use immutable objects
• Question the hierarchy
– Circle.asEllipse()
Circle-ellipse problem — solutions

• Let your modules depend on each other
– Enlarge your coupling!
Circular dependency

• Acyclic Dependencies Principle
– Have a Directed Acyclic Graph of dependencies
Circular dependency — solution

• Dependency Inversion Principle
Circular dependency — solution

• When your domain objects contain little or no business logic
Anemic domain model

• Any benefits?
• Clear separation between logic and data
• “Pure fabrication” pattern support
– “Service” classes
Anemic domain model

• Liabilities?
− Not really object-oriented way
− Data can be inconsistent (no validation)
− Increased coupling
Anemic domain model

• One class to rule them all
Monster object

• Hard to maintain
• No “Single responsibility”
• Testability problems
Monster object — drawbacks

• Beware of: …Driver, …Manager, …System
• Follow SRP
• Use testability as a problem detector
Monster object — solution

• Extend a utility object to have access to its methods
– Bonus: strange hierarchy
– Bonus: unexpected internals
BaseBean

• Use delegation
• “Composition over inheritance” principle
– Interfaces help decoupling
BaseBean — solution

• A retro-style way of shortening constants
• Pollutes the class namespace
• Not a part of implementing class API
Constant interface

• Do it modern style!
– Create a class with constants
– Use static imports
Constant interface — solution

• When methods order is important
Sequential coupling
Hmm… or maybe?

• Be suspicious about start…(), init…() methods
• Don’t reveal your class details
• Use “Template method” pattern
Sequential coupling — solution

• Circle-ellipse problem
• Circular dependency
• Anemic domain model
• Monster object
• BaseBean
• Constant interface
• Sequential coupling
Object-oriented design anti-patterns

• The way the system is designed
– on architectural level
Software design anti-patterns

• More features, less benefits
Software bloat
• Plug-ins (extensions, add-ons)
• Similar anti-patterns?

• Architecture?
No time for this!
Big ball of mud
• Reasons:
– business pressure
– developers rotation
• Symptoms
– bugfixing as a main task
– maintenance nightmare

• Everything can be improved
a bit more
– when should you stop?
Gold plating
• Efforts distribution
• Pareto principle (80/20)

• Software bloat
• Big ball of mud
• Gold plating
• …
Software design anti-patterns

• Everyone knows the project is going to fail
– But the truth is hidden to prevent project cancellation
• Alternatively: unreasonable deadline
– And unnecessary overtime work
Death march

• Rely on heroic efforts (of one or more persons)
– Even base estimates on them
Hero mode
• Solutions:
– Make honest estimates
– Distribute tasks
– Don’t reward heroic behavior

• “No-no, we cannot do anything in this module without John!”
• “I don’t know about it. Ask Mary, she has written all this code.”
• “I like to work alone. It’s just my way of working.”
Lonely rider
• Solutions:
– If you have an irreplaceable person — replace him ASAP
– Knowledge sharing
– Peer reviews
– Mentoring to less experienced
developers

• Pay too much attention to measurement data
– Due to your ignorance or on purpose
Metric abuse
• Solutions:
– Ensure that everyone understands metrics meanings
– Remember: metrics are means, not goals

• Seagull manager
– flies in,
– makes a lot of noise,
– craps on everything
– and flies out again.
Seagull management
• Solutions:
– … show him this definition?

• Death march
• Hero mode
• Lonely rider
• Metrics abuse
• Seagull management
• …
Project management anti-patterns

• “Measure thrice and cut once”
– Some people prefer to measure even more times…
Analysis paralysis
• In software development:
long phases of
– project planning
– requirements gathering
– program design
– …

• “Two heads are better than one”
– The more heads, the better?
Design by committee
• Many contributors, but no unifying vision

Escalation of commitment
• English proverb: “Throw good money after bad”
• Examples:
– Bidding wars (“Dollar auction”)
– Trying to revive the inevitably dying project

• Use a vendor you can’t change without losses
Vendor lock-in
• Examples:
– SIM locking
– Gift certificates
– Sony Memory Stick
– External service or framework
• Solution:
– Isolation layer

• Analysis paralysis
• Design by committee
• Escalation of commitment
• Vendor lock-in
Organizational anti-patterns

• Use link text that does not correspond to the target
“Click here”
For downloading demo version, click here.
For reading the online documentation, click here.
You can download demo version
or read the online documentation,

• Open your menu on hover, not on click
– And hide it once the cursor is out
– That will train visitors’ fine motor skills. And patience.
Hover menus

• Make important icon/link too small
– Yes, fine motor skills again
Tiny targets
► Gadgets
► Buildings
► Food
▼ Transport
► DeLorean
► Hoverboard
Only bullets are clickable

• Is it a switch or an indicator?
Mixing status and action

• Let switch indicate its state:
Mixing status and action

• Show all the power of your software at once!
Bloated interface

• “Click here”
• Hover menus
• Tiny targets
• Mixing status and action
• Bloated interface
UI anti-patterns

One problem…
Conclusion

Different layers…
Conclusion

Different anti-patterns
Conclusion

Any other examples?
Conclusion

Hope for your feedbacks!
Thank you

Thank you
Andrei I. Uvarov
Java developer
andrew.uvarov@returnonintelligence.com

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