The Pragmatic Programmer - Chapter 7: While You Are Coding

• Listen to your inner lizard.
• Prototype when stucked.
• Avoid programming by coincidence.
• Don’t assume it, prove it (again)!

Algorithm Speed

• Estimate the order of your algorithm.
• Test your estimates.
• Always be wary of premature optimization.

Refactoring

• Software engineering is more like gardening than construction - More organic than concrete.
• Acording to Martin Fowler:
  • Refactoring is disciplined.
  • External behaviour does not change.
• Refactoring is a day-to-day activity, taking low-risk and small steps.
• Refactor early, refactor often.
• Martin Fowler’s Tip for refactoring:
  • Don’t try to refactor and add functionality at the same time.
  • Make sure you have good tests before you begin refactoring. Run it often.
  • Take short and deliberate steps.

Test To Code

• Testing is not about finding bugs.
• A test is the first user of your code.
• The higher the testability, the lower the coupling.

One of the most important aspects of the software development is that we don’t know what we are doing when we start.

• Build end-to-end, not top-down or bottom-up.
• Design to test.
• Log messages should be in a regular and consistent format because you may want/need to parse them automatically to deduce processing time or logic paths that the program took.
• Test, design, coding - it’s all programming.

Property-Based Testing

• Use property-based tests to validate your assumptions.
• Property = contracts + invariants
• For Python, use hypothesis library.

Stay Safe Out There

• Security basic principles:
  1. Minimize attack surface area.
     • Complex code makes the surface more porous and open to infection. Simpler, less complex code is easier to spot potential weakness.
     • Always sanitize external data.
     • Add auth to your service.
     • Remove unused auth users.
     • Don’t give away informations through log and debugging.
  2. Principle of less privilege
     • Every program and privileged user of the system should operate using the least amount of privilege necessary to complete the job.
  3. Secure defaults
     • The default should be the most secure values.
  4. Encrypt sensitive data
     • Keys and secrets need to be managed separately, generally via config files or environment variables.
  5. Maintain security updates
     • Apply security patches quickly.
• You want to encourage long, random passwords with a high degree of entropy.
• Cryptography: NEVER do it yourself!

Naming Things

• “The beggining of wisdom is to call things by their proper name.” Confucius
• Honor the local culture.
• Be consistent.
• Name well; Rename when needed.
• Make renaming easy; Rename often.