You were just handed the keys to a new repo. Your first glance over the code base causes the fearful "LEGACY" word to ring in your head. HAVE NO FEAR! I'll share the techniques I've learned after working on several legacy codebases to help update that old code to the current PHP generation. We'll cover triaging the old code base, writing tests to make sure you don't break anything, and how to modernize your old code base!

1. So You Just Inherited a
$Legacy Application...
https://joind.in/talk/4d6d9
Joe Ferguson

2. Who Am I?
Joe Ferguson
PHP Developer
Twitter: @JoePFerguson
Organizer of @MemphisPHP
@NomadPHP Lightning Talks
PHP FIG Secretary
Passionate about Community

3. For Further Reading
leanpub.com/mlaphpleanpub.com/minimumviabletests

4. Legacy Applications

5. First: A Warning

6. “There are no solutions,
only trade offs”
- Joe Ferguson
- Paul M. Jones
- Thomas Sowell

7. What is a "Legacy" application

8. Legacy is often used for an older production
application that was written before, or without
regard for modern technologies or practices.

9. If you ask Wikipedia…
"... no-longer supported …"
"... maintained by an administrator that did not develop the code
…"
"... supporting older file formats ..."
https://en.wikipedia.org/wiki/Legacy_code

10. Modern Interpretation
"... source code inherited from someone else …"
"... source code inherited from an older version of the software ..."

11. Some people say…
"Any code in production is not legacy”
"Any code written X years ago is legacy"

12. Legacy is all these things
As we talk about Legacy code here,
we're really talking about all of these definitions

13. This process is not Legacy
Specific…

14. Inheriting a Legacy App
Precontemplation or Shock/Disbelief
Contemplation and/or Anger
Determination and Bargaining
Action and Reconstruction
Maintenance and Acceptance

15. Precontemplation or Shock/
Disbelief

16. This is the initial
"what is this?!"

17. That’s now how this works!

18. Precontemplation
Not ready for change (project, code base, etc)
Usually you don’t know the depths of issues
Can sometimes lead to assuming the worst
Usually this is the shortest phase due to business needs

19. Shock/Disbelief
This is where the WTFs and the WTHs should be left
Try to work through any negativity here
Be positive about the previous developer’s intentions

20. Contemplation and/or Anger

21. This is the planning phase

22. Try to get all of your ager at the code
base out during this phase, it will help
you see the path forward.

23. Taking stock of what we’re
working with

24. Initial Project Overview
Is there a framework?
Is there a coding standard?
Is there any autoloading?
How are dependencies behind handled?
Is there an ORM or how is the database being utilized?
Is there a development environment?

25. Is there a framework?

26. Is there a coding standard?

27. No Standard? No problem!

28. Is there any autoloading?

29. There is a PSR for that…

30. How are dependencies behind
handled?

31. Is there an ORM or how is the
database being utilized?

32. Is there a development
environment?

33. Tools to help

34. PHP Coding Standards Fixer
http://cs.sensiolabs.org/

35. PHP Coding Standards Fixer
php-cs-fixer fix app --dry-run

36. PHP Mess Detector
https://phpmd.org

37. PHP Mess Detector
https://phpmd.org
$ phpmd app html cleancode --reportfile report.html

38. Warning about Automating
Code Changes

39. Composer
https://getcomposer.org/doc/01-basic-usage.md

40. Doctrine
http://www.doctrine-project.org

41. Propel
http://propelorm.org

42. Local Dev Environments
Physical Hardware
Vagrant (Virtual Machines)
Docker (Containers)

43. Physical Hardware

44. Vagrant

45. PuPHPet.com

47. Docker For Developers
leanpub.com/dockerfordevs

48. Determination and Bargaining
Decision making and triage time

49. Triage
Address any critical things found in Contemplation phase
PHP version issues
Fixing critical vulnerabilities

50. You have a plan and now you
need to estimate this plan.

51. I hate estimating
nomadphp.com/2016/04/06/stop-
multiplying-4/
Lightning talk by Chuck Reeves
(@manchuck)
Short and sweet talk about how to
do better estimating

52. No Question Left Behind!
The application has no framework, We’re going to use a micro
framework as we refactor.
The application has no autoloading, But we’re using Composer
Dependencies are checked into version control, But we’re using
Composer
There is no ORM, but we’re going to use Propel
We have no dev environment but we’re going to use Vagrant

53. Proof of Concept
Any new things introduced should be tested to ensure
functionality
Build out a small example of an area you or the team doesn't fully
comprehend so you can address any questions that may arise

54. Bargaining
Getting stakeholders on board with your estimates
Do the decisions made thus far make business sense?
Are there any doubts in the plan?

55. “We should just rewrite the app”

56. "This would be so much easier in
framework _____________”

57. Why not rewrite?
Progress halts entirely
Business logic is rarely reused
Most of the time is getting back to
current functionality

58. Why you should refactor
Progress continues
Business logic reused
Modernizing functionality instead
of recreating

59. Make Decisions
Build Proof of Concept(s)
Ensure stakeholder buy in
Avoid the allure of green fields**
** in some cases a rewrite is warranted

60. Action and Reconstruction

61. Existing Tests
This is great!
Review the tests to get an idea of coverage
Passing tests become your control for any upcoming changes
Confidence++

62. No Existing Tests
Not the end of the world!
Inspect the code base, was it written to be easily testable?
Could you easily mock dependencies?

63. Untestable Code
Not all code is testable
If you can’t easily unit test the code base, consider alternatives
Functional testing and Acceptance testing are valid options

64. Acceptance Testing
NOT a replacement for Unit Testing
Test large parts of your application at a time
Can be harder to pinpoint error location
Gives large code coverage in short amount of time

65. Digging into the Code
Code Consolidation

66. Digging into the Code
Code Consolidation
Replace globals with DI

67. Digging into the Code
Code Consolidation
Replace globals with Dependency Injection
Write tests

68. Digging into the Code
Code Consolidation
Replace globals with Dependency Injection
Write tests
Extract SQL (to ORM or other)

69. Digging into the Code
Code Consolidation
Replace globals with Dependency Injection
Write tests
Extract SQL (to ORM or other)
Extract Business Logic (To domain logic)

70. Digging into the Code
Code Consolidation
Replace globals with Dependency Injection
Write tests
Extract SQL (to ORM or other)
Extract Business Logic (To domain logic)
Extract Presentation Logic to Views (Twig, Blade, etc)

71. Digging into the Code
Code Consolidation
Replace globals with Dependency Injection
Write tests
Extract SQL (to ORM or other)
Extract Business Logic (To domain logic)
Extract Presentation Logic to Views (Twig, Blade, etc)
Extract Action Logic (To Controllers)

72. Digging into the Code
Code Consolidation
Replace globals with Dependency Injection
Write tests
Extract SQL (to ORM or other)
Extract Business Logic (To domain logic)
Extract Presentation Logic to Views (Twig, Blade, etc)
Extract Action Logic (To Controllers)
Write (more) tests

73. Maintenance and Acceptance

74. Maintenance and Acceptance
Code Consolidation
Replace globals with Dependency Injection
Write tests
Extract SQL (to ORM or other)
Extract Business Logic (To domain logic)
Extract Presentation Logic to Views (Twig, Blade, etc)
Extract Action Logic (To Controllers)
Write (more) tests

75. Maintenance and Acceptance
Adding Features
More New Code
Less Refactoring
Maintain your processes

76. Continuous Integration

77. Revisit Acceptance Tests

78. Resources / Q & A
Modernizing Legacy Applications In PHP - Paul M. Jones
https://leanpub.com/mlaphp
Minimum Viable Tests - Chris Hartjes
https://leanpub.com/minimumviabletests
Code Style https://github.com/FriendsOfPHP/PHP-CS-Fixer, http://editorconfig.org
php mess detector https://phpmd.org
Autoloading PSR-4 https://getcomposer.org/doc/01-basic-usage.md
ORMs http://www.doctrine-project.org http://propelorm.org
Docker https://leanpub.com/dockerfordevs, Vagrant https://puphpet.com

79. Feedback!
https://joind.in/talk/4d6d9
Joe Ferguson
Twitter: @JoePFerguson
Email: joe@joeferguson.me
Freenode: joepferguson
Contact Info: