Top 5 ways to improve your code

Top 5 Ways to Improve Your CodeEric De CarufelAgile Coach

http://blog.decarufel.nethttp://pyxis-tech.com

Introduction• Legacy code is code

without tests• Michael Feather in Working

effectively with legacy code• Without continuous

maintenance the code will degrade rapidly

• We need to detect and remove code smell

Reduce class

hierarchy

Increase class collaboration

Reduce coupling

Increase cohesionUse one abstraction level per method

Use layer architectureExtract cross cutting concerns

1. Simplify conditionals

2. Improve code documentation

3. Improve method calls

4. Manage scope

5. Remove dead code

My Top 5 Improvements

1. Simplify conditionals – Why?• Reduced complexity• Better readability• Better maintainability• Better reusability

1. Simplify conditionals –When?• There is more than one condition (and / or)• There is too much code in the body• The condition is based on type• There are nested if statements• There are many decisions based on the

same info (if else if chain / switch case)

1. Simplify conditionals – How?• Refactor conditional statements

• Decompose conditional code• Consolidate conditional expressions• Consolidate duplicate conditional fragments• Introduce null objects• Flatten nested if• Don't use negative conditions• Keep conditional statements lean

• Avoid conditional statements• Replace conditional code with polymorphism• Replace conditional logic with strategy• Replace conditional dispatchers with commands

Decompose Conditional Code

Consolidate Conditional Expressions

Consolidate Duplicate Conditional Fragments

Introduce Null Objects

Flatten Nested if

Don't Use Negative Conditions

Keep Conditional Statements Lean• Do your best to have only one condition

• Use methods to combine multiple conditions• Invert your conditions if most (or all) the

code of your method is inside the "true" block• Make sure to avoid double negation

Replace Conditional with Polymorphism

Replace Conditional Logic with Strategy

Replace Conditional Dispatcher with Command

2. Delete comments – Why?• Better readability• Better maintainability• Fewer obsolete comments

2. Delete comments – When?• Every time there is a comment that is not (useful)

information, intention, clarification, warning, TODO or amplification.

• Comments are the only content of a code section• Empty catch statements

• Your comments describe line by line what you are trying to do• Example:

// Getting connection string from configuration// Opening connection// Retrieving data// Closing connection

2. Delete comments – How?• Replace comments with good naming

• Extract methods• Use meaningful names

• Write useful comments• Naming Conventions (MSDN: Guidelines for names)

• Properties• Enums• Events• Methods

Extract Methods

Use Meaningful Names• Use Intention-Revealing names• Avoid disinformation• Make meaningful distinctions• Use pronounceable names• Avoid encoding• Avoid mental mapping• Class names -> nouns not verbs• Method names -> verbs• Don't be cute. Use standard names• Solution Domain Names vs Problem Domain Names

Properties• Do use PascalCase naming• Do name properties with a noun, noun phrase or

an adjective• Do Not use names that match Get method• Do name booleans with Can, Is or Has prefix

Enums• Consider the first element to be the

default value• Do use PascalCasing naming• Single choice enumerations should

be singular• Bit fields enumerations should be

plural and have Flags attibute• Value of bit fields enumeration

should be coherent (Read & Write == ReadWrite)

Events• Do use PascalCase naming• Do name event using a verb, present progressive for pre-event and past

for post-event

• Do provide a virtual version of the event to override

• Do provide a way to cancel pre-event

Methods• Do give methods names that are verbs or

verb phrases• ProcessPayment

• Do express the return value in method name • CreateCustomer• GetInvoice

• Use consistent naming (Get, Fetch or Retrieve but not all in same context)

3. Clarify contracts – Why?• Better performance• Better readability• Better reusability

3. Clarify contracts – When?• There are too many parameters (how

many is too many?)• A method does more than one thing• A method uses out parameters• You need default values

3. Clarify contracts – How?• Reduce number of parameters

• Introduce parameter object• Create overloads with less parameters• Use default values

• Function output• Return type value• Use out parameters

• Overload methods in proper order

Introduce Parameter Object

Create Overloads with Fewer Parameters

Use Default Values

4. Reduce scope – Why?• Avoid side effects• Better reusability• Better maintainability

4. Reduce scope – When?• A field is used in only a few methods• Public members expose class behavior

4. Reduce scope – How?• Reduce visibility

• Use protected• Use private• Use Internal

• Reduce scope• Move fields to method• Split class• Move local variable close to its use

• Reduce lifetime• Initialize late• Reduce references• Free early

5. Remove Dead Code – Why?• Because you must• Better maintainability• Better performance• Better readability• 100% test coverage

5.Remove Dead Code – When?• You know the code is dead• You think the code is dead• You want that code to be dead

5. Remove Dead Code – How?• Identify and remove dead code

• Delete the code• Compile• Run the tests

• What is dead code?• Commented code.• Any line of code that is not covered by unit tests.

• Tools• There are tools that delete all code not covered by unit

tests.

Next Steps• Improve your conditional code• Improve your documentation• Improve your method calls

Resources• Refactoring – Improving the design of existing code

• Author: Martin Fowler• Edition: Addison Wesley• ISBN: 978-0-201-48567-7

• Refactoring to patterns (Martin Fowler signature)• Author: Joshua Kerievsky• Edition: Adison Wesley• ISBN: 978-0-321-21335-1

• Clean code – a handbook of agile software craftsmanship• Author: Robert C. Martin• Edition: Prentice Hall• ISBN: 978-0-132-35088-4

• Working effectively with legacy code• Author: Michael C. Feather• Edition: Prentice Hall• ISBN: 978-0-13-117705-5

Related sessions• Day 2 – 08h45 to 10h00

• DEV373 – Testing with Microsoft Visuals Studio Test Professional and the new Team Lab 2010by Etienne Tremblay

• Day 2 – 10h30 to 11h45• ARC301 – Design by Contract (DbC) and Code

Contracts in Visual Studio 2010by Joel Hebert

Remember To Complete Your Evaluations!

You could WIN a Samsung Focus Windows Phone 7!Let us know what you liked & disliked!Remember, 1=Bad, 5=Good Please provide comments!No purchase necessary. The contest is open to residents of Canada (excluding government employees). The Toronto Tech·Days evaluation form contest begins on October 25 th, 2011 and ends on October 26th, 2011. The Vancouver Tech·Days evaluation form contest begins on November 15 th, 2011 and ends on November 16th, 2011. The Montreal Tech·Days evaluation form contest begins on November 29th, 2011 and ends on November 30th, 2011. Participants can enter the contest in one of two ways: (1) complete and submit an evaluation form by the contest close date; or (2) provide contact information by the contest close date. The draw for Toronto will take place on October 31 st, 2011. The draw for Vancouver will take place on November 21st, 2011. The draw for Montreal will take place on December 5th, 2011. The chances of being selected depend upon the number of eligible entries. Selected participants will be contacted by phone and/or e-mail and will be required to answer correctly a time-limited skill-testing question. There are three (3) prizes available to be won. One (1) prize will be given away for each Tech·Days event in Toronto (October 25-26 2011), Vancouver (November 15-16 2011) and Montreal (November 29-30 2011). The prize consists of a Samsung Focus Windows Phone 7 (handset only; voice and/or data plan not included) (approximate retail value of $499 CAD). The prize will be delivered to the shipping address designated by the winner within 6-8 weeks. The winner may be required to sign a declaration and release form. For full contest rules, please see a Microsoft Tech·Days representative.

You can email any additional comments directly to td_can@microsoft.com at any time.

Q & A

© 2011 Microsoft Corporation. All rights reserved. Microsoft, Windows, Windows Vista and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries.

The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this

presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.