@page Other @subpage Architecture @page Architecture Achitecture

* Note, limitation of markdown to create a non-rectangular table cell

Basic Principles

• DRY - Don't Repeat Yourself
• Orthogonality
• Software Layering
• Referential Transparency
• Test driven development
• Data oriented design

DRY

• Avoid duplication
• Smaller
• Removes fixing bugs multiple times

Orthogonality

• Modular
• Separation of concerns
• Testability
• Maintainability

Software Layering

• Pragmatic approach to orthoginality
• Can re-use code more by allowing higher layers to be built from lower layer components
• Avoiding inversion of control

Referential Transparency

• Do not mutate the input or global or internal state
• Avoids side-effects
• Same input means same output
• Testability
• Maintainability
• Scalability - Concurrent

Test driven development

• Given a specification of what you want a module to do, then
• write tests that assert that each requirement is met, then
• write the code to pass all the tests

Data oriented design

• This is in contrast to object oriented design
• Basic idea is that many computational tasks are not bottlenecked by the CPU the bottleneck is accessing memory. RAM access is vastly slower than calculations.
• Rearranging layout of data to improve locality of access can yield speed improvements greater than an improved algorithm that on apearances is computationally less expensive.