dsilfen-handy

Refactoring Ruby: Chapter 2

Principles in refactoring

What is refactoring?

• Fixing code the second time around, because programmers rarely write good code the first time

Noun: a change to made to the internal structure of software to make it easier to understand and cheaper to modify without changing its observable behavior

dsilfen-handy

Pragmatic Programmer: Chapter 6

What to think about while writing code

---

Programming By Coincidence

• Untrue assumptions are like landmines, and tend to blow up in our faces at inopportune times.
• Before changing code, one should have a good handle understanding of how the current implementation works.

dsilfen-handy

grep shotgun docker-compose.development.yml
if [ $? -eq 0 ] ; then
    perl -p -i -e "s/shotgun/unicorn/g" docker-compose.development.yml
else
    perl -p -i -e "s/unicorn/shotgun/g" docker-compose.development.yml
fi

dsilfen-handy

Pragmatic Programmer: Chapter 3

Learning basic tools to feel comfortable constructing your own toolkit

Power of plain text:

• Insurance against obsolescence 
  • Self describing data carries context with data. Look at application.yml to see keys and their meaning. Many elements describe their purpose with their name.
• Leverage
• grep/ag/ruby/python/perl/bash/sh

dsilfen-handy

CURRENT_BRANCH=$(git describe --contains --all HEAD)
PREVIOUS_BRANCH=$(git for-each-ref --sort=committerdate refs/heads/ | tail -n 1 | cut -c 60-)
TWO_BACK_BRANCH=$(git for-each-ref --sort=committerdate refs/heads/ | tail -n 2 | head -n 1 | cut -c 60-)
if [[ $CURRENT_BRANCH == $PREVIOUS_BRANCH  ]]; then
  GITCOMMAND="git checkout ${TWO_BACK_BRANCH}"
else
  GITCOMMAND="git checkout ${PREVIOUS_BRANCH}"
fi

eval $GITCOMMAND

dsilfen-handy

Chapter 6 - Acquiring Behavior Through Inheritance

What is inheritance?

• Automatic Message Delegation - Defining a path for forwarding messages an object does not understand.
• Defining an inheritance relationship will automatically forward messages from the child to the parent if they are misunderstood (or if they are explicitly called with super
• Multiple Inheritance VS. Single Inheritance
  • Languages like Python allow more than one parent class
  • Ruby features single inheritance

dsilfen-handy

Rake it 'Til you make it

Tips on making resiliant rake tasks for data cleanup

Your script should have the following features:

1. Print the output, show progress in the stdout to make it
2. Provide a limit argument, so you can test on a small subset
3. Provide a offset argument, so you can skip already processed rows

dsilfen-handy

Chapter 2 - Single Responsibility Principle (SRP)

What belongs in a class?

Flexible code as a truth

• T.R.U.E.
  • Transparent: Consequences of changing the code should be obvious in the code it is changing and in distant code it relies upon
  • Reasonable: The cost of changing the code should be porportional to any benefits one might gain. (Small change == Small gain, big change == big gain)
  • Usable: Existing code should be usable in new and unexpected contexts

dsilfen-handy

Chapter 1 - Principles of OOP

Problems to solve

• Flexibility (The only certainty in life is change!)
• Dependency Management
• Cost of development
  • Avoiding design that anticipates future feature requirements

Definition of Design

dsilfen-handy

ActiveGripes

MyProblems::With::ActiveRecord

• What does << actually do for a has_many relation
• Use of transactions with find_or_create_by
• Are you sure you exist?
• Racing to find_or_create records!