Domain at the core, simplicity and design principles is what makes the code maintainable.

1. SoftwareSoftware
MantenibleMantenible
Carlos Blé
@carlosble

2. About meAbout me
Developer, Speaker, Author, Trainer, Entrepreneur
Founder of Lean Mind
Software Craftsmanhip Community Member
Brought SoCraTes to the Canary Islands
Co-founder of Agile Canarias & Agile Spain
@carlosble

3. @carlosble

4. Why is it hard to maintain?Why is it hard to maintain?
1 - Don’t consider your audience
when writing new code
2- Don’t refactor every day
@carlosble

5. Consider your audienceConsider your audience
Don’t aim for reusability
●
Accidental Complexity
●
Painful generalizations
●
Premature optimizations
Standards are not
enough
●
Frameworks, Three tiers, MVC,
MVP...
●
File per class, small code units, PR,
metrics
●
Linters, Compilers, Coding
standards
●
Quality Attributes
@carlosble
Explicit domain core
✔
Names and abstractions
✔
Avoid primitives
✔
Domain Driven Design
✔
Design Principles
✔
Tests as documentation
✔
Framework agnostic
✔
Database structure agnostic
Paradigms don’t solve
the problem either
●
Imperative, Declarative
●
Multi-paradigm

6. Domain at the coreDomain at the core
- yes! also in the front-end- yes! also in the front-end
@carlosble
input
Data
Store
output
Infrastructure:
- Controller
- Component
- Action
- ViewModel
- Dispatcher
DOMAIN CORE
Infrastructure:
- Repository
- Mapper
- Client
- DTO
- Mailer
3rd
party
system
output
Service
Entity
Value Object
Entity
Delivery
mechanism
Domain core doesn’t know the outer layers
(clean architecture: mind dependencies’ direction)

7. Example: Interaction-Driven DesignExample: Interaction-Driven Design
@carlosble
Image from Sandro Mancuso, author of IDD
https://dzone.com/articles/introducing-interaction-driven-design

8. You’re wrong anyway, refactor please!You’re wrong anyway, refactor please!
It’s about ROI
●
Avoid analysis paralysis
●
Small thoughtful changes keep the
project on the green field
●
We re-discover the business as we
work on it
●
Code is the single source of truth
Balance
●
Aim for decent quality, not
perfection
●
Technical debt under control
●
Proud of a well-done job
●
Control your optimism
@carlosble
Every day
●
Warm up reading yesterday’s
code, like a kata
●
Automatic changes with an IDE
●
Pair review, Pair programming
Pick your battles
●
The low hanging fruit
●
Refactor to understand the code
●
Discard your changes when
needed
●
Delete all the lines you safely could
●
If it works don’t touch it

9. Thank you!Thank you!
@carlosble