The Art of Ruby

Matthew Mongeauhalogenandtoast

[email protected]

The Art of Ruby

A programmer who subconsciously views himself as an artist will enjoy

what he does and will do it better.

Donald Knuth

What is Art?

/ärt/the expression or application of human creative skill and imagination, typically in a visual form such as painting or sculpture, producing works to be appreciated primarily for their beauty or emotional power.

/ärt/the expression or application of human creative skill and imagination, typically in a visual form such as painting or sculpture, producing works to be appreciated primarily for their beauty or emotional power.

What is Art

It’s beautiful.

What is Art

It’s beautiful.It’s creative.

What is Art

It’s beautiful.It’s creative.It’s expressive.

What is Art

What is Programming

The art of writing code.

Code is Art

It’s beautiful.

Code is Art

It’s beautiful.It’s creative.

Code is Art

It’s beautiful.It’s creative.It’s expressive.

Code is Art

Writing beautiful Code

Simplicity

Code should be clear

def play puts "Welcome to the guessing game." 3.times do guess = get_guess if won? guess @won = true puts "You win!" break else puts "Wrong!" end end if !@won puts "You lost. The actual number is #{@actual_number}." endend

def play puts "Welcome to the guessing game." 3.times do guess = get_guess if won? guess @won = true puts "You win!" break else puts "Wrong!" end end if !@won puts "You lost. The actual number is #{@actual_number}." endend

def play puts "Welcome to the guessing game." play_rounds print_resultsend

Extract MethodPattern

def play print_header play_rounds print_resultsend

Single Level of Abstraction

Principle

Complexity

Balance

def play_rounds round_count.times do if correct_guess? get_guess @won = true break else puts "Wrong!" end endend

def play_rounds @won = round_count.times.detect { play_round }end

def play_round if correct_guess? get_guess true else puts "Wrong!" endend

def play_rounds @won = round_count.times.detect { play_round }end

def play_round if correct_guess? get_guess true else puts "Wrong!" # this returns nil which is falsey endend

Constraints

The more constraints one imposes, the more one frees one's self.

Igor Stravinsky

Code Constraints

Code Constraints

5 line methods

Code Constraints

5 line methods100 line classes

Code Constraints

5 line methods100 line classesNo classes in public methods

def play puts "Welcome to the guessing game." 3.times do guess = get_guess if won? guess @won = true puts "You win!" break else puts "Wrong!" end end if !@won puts "You lost. The actual number is #{@actual_number}." endend

def play print_header play_rounds print_resultsend

def play_rounds round_count.times do if correct_guess? get_guess @won = true break else puts "Wrong!" end endend

def play_rounds @won = round_count.times.detect { play_round }end

def play_round if correct_guess? get_guess true else puts "Wrong!" endend

def play_rounds @won = round_count.times.detect { play_round }end

def play_round if correct_guess? get_guess true else puts "Wrong!" # this is still bothering me endend

Breaking the Rules

Pablo

Picasso

Learn the rules like a pro, so you can break

them like an artist.

def play_round if correct_guess? get_guess true else puts "Wrong!" endend

def play_round if correct_guess? get_guess puts "Correct" true else puts "Wrong!" false endend

def play_round if correct_guess? get_guess correct_guess else incorrect_guess endend

def incorrect_guess puts "Wrong!" falseend

def correct_guess puts "Correct" falseend

def play_round if correct_guess? get_guess correct_guess else incorrect_guess endend

def incorrect_guess puts "Wrong!" falseend

def correct_guess puts "Correct" falseend

class Guess def initialize actual_number @actual_number = actual_number @guess = get_guess end

def status if correct? "Correct" else "Incorrect" end end

def correct? guess == actual_number end

private attr_reader :guess, :actual_number

def get_guess print "What is your guess: " gets.to_i endend

Extract Class

Pattern

def play_round guess = Guess.new(actual_number) puts guess.display_status guess.correct?end

Extract Class

Pattern

Extract Method

1

Extract Method Extract Class

1 2

Extract Method Extract Class Extract Gemor App

1 2 3

You Win

Performance

If you’re willing to restrict the flexibility of your approach, you can almost always do something better.

John Carmack

module Alchemist module Conversion def method_missing unit_name, *args, &block exponent, unit_name = Alchemist.parse_prefix(unit_name) if Alchemist.has_measurement?(unit_name) Alchemist.measurement self, unit_name, exponent else super( unit_name, *args, &block ) end end endend

class Numeric include Alchemist::Conversionend

module Alchemist module Conversion def method_missing unit_name, *args, &block exponent, unit_name = Alchemist.parse_prefix(unit_name) if Alchemist.has_measurement?(unit_name) Alchemist.measurement self, unit_name, exponent else super( unit_name, *args, &block ) end end endend

class Numeric include Alchemist::Conversionend

def self.parse_prefix(unit) matches = unit.to_s.match(prefix_matcher) prefix, parsed_unit = matches.captures

if prefix && si_units.include?(parsed_unit) value = prefixed_value_for(prefix.to_sym, parsed_unit) [value, parsed_unit.to_sym] else [1, unit] end end

def self.parse_prefix(unit) matches = unit.to_s.match(prefix_matcher) prefix, parsed_unit = matches.captures

if prefix && si_units.include?(parsed_unit) value = prefixed_value_for(prefix.to_sym, parsed_unit) [value, parsed_unit.to_sym] else [1, unit] end end

def self.parse_prefix(unit) matches = unit.to_s.match(prefix_matcher) prefix, parsed_unit = matches.captures

if prefix && si_units.include?(parsed_unit) value = prefixed_value_for(prefix.to_sym, parsed_unit) [value, parsed_unit.to_sym] else [1, unit] end end

def self.prefix_matcher keys = unit_prefixes.keys.map(&:to_s). sort{ |a,b| b.length <=> a.length } %r{^(#{keys.join('|')})?(.+)} end

[:googol, :yotta, :Y, :zetta, :Z, :exa, :E, :peta, :P, :tera, :T, :giga, :G, :mega, :M, :kilo, :k, :hecto, :h, :deca, :da, :deci, :d, :centi, :c, :milli, :m, :micro, :u, :nano, :n, :pico, :p, :femto, :f, :atto, :a, :zepto, :z, :yocto, :y, :kibi, :Ki, :mebi, :Mi, :gibi, :Gi, :tebi, :Ti, :pebi, :Pi, :exbi, :Ei,

:zebi, :Zi, :yobi, :Yi]

/^(googol|yotta|femto|zetta|zepto|micro|milli|centi|hecto|yocto|exbi|giga|tebi|mega|pebi|kilo|atto|tera|kibi|deca|yobi|deci|pico|nano|gibi|zebi|mebi|peta|exa|Ki|Mi|Gi|Zi|da|Ei|Ti|Pi|Yi|z|a|y|f|p|n|m|c|d|

h|k|M|G|T|P|E|Z|Y|u)?(.+)/

Some people, when confronted with a problem, think "I know, I'll

use regular expressions." Now they have two problems.

Jamie Zawinski

I thought

"I know, I'll use regular expressions."

I now had two problems

but

def self.prefix_matcher @prefix_matcher ||= begin prefix_keys = unit_prefixes.keys.map(&:to_s). sort{ |a,b| b.length <=> a.length } %r{^(#{prefix_keys.join('|')})?(.+)} endend

2.0

1.9

Keep existing interface

Constraints

Keep existing interfaceNo method_missing

Constraints

Keep existing interfaceNo method_missingIncrease performance

Constraints

module Alchemist

def self.setup category = nil if category load_category category else load_all_categories end end

private

def self.load_all_categories library.load_all_categories end

def self.load_category category library.load_category category endend

module Alchemist class ModuleBuilder def initialize category @category = category end

def build Module.new.tap do |category_module| category_module.class_eval %(def self.inspect() "#<Module(#{category})>" end) category_module.class_eval category_methods end end

private attr_reader :category

def library Alchemist.library end

def category_methods unit_names.map do |name| %(define_method("#{name}") { Alchemist.measure self, :#{name} }) + "\n" + prefixed_methods(name) end.join("\n") end

def unit_names library.unit_names(category) end

def prefixes_with_value(name) if library.si_units.include?(name.to_s) library.unit_prefixes else [] end end

def prefixed_methods(name) prefixes_with_value(name).map do |prefix, value| %(define_method("#{prefix}#{name}") { Alchemist.measure self, :#{name}, #{value} }) end.join("\n") end

module Alchemist class ModuleBuilder def initialize category @category = category end

def build Module.new.tap do |category_module| category_module.class_eval %(def self.inspect() "#<Module(#{category})>" end) category_module.class_eval category_methods end end

module Alchemist class ModuleBuilder def initialize category @category = category end

def build build_module do |category_module| define_inspect_method(category_module) define_unit_methods(category_module) end end

[success_kid.jpg]

the c-levelthe c-level#include <ruby.h> #include <string.h>

VALUE cParenParser;

VALUE paren_parser_parse(VALUE self, VALUE str) { const char *c_str = RSTRING_PTR(str); char *temp = (char *)malloc(sizeof(char) * RSTRING_LEN(str) + 1); int temp_pos = 1; int c_str_pos = 0; temp[0] = c_str[0]; while(c_str[c_str_pos++] != '\0') { if(temp_pos > 0 && temp[temp_pos-1] == ')' && c_str[c_str_pos] == '(') { temp_pos--; } else { temp[temp_pos++] = c_str[c_str_pos]; } } temp[temp_pos] = '\0';

return rb_str_new2(temp);}

void Init_paren_parser() { mParenParser = rb_define_module("ParenParser"); cParser = rb_define_class_under(mParenParser, "Parser", rb_cObject); rb_define_method(cParser, "parse", paren_parser_parse, 1);}

How to be an artist

Have a toolbox

Be inspired by others

Surround yourself with talented artists

Surround yourself with talented artists

Use well known techniques

Use well known techniques

Measure improvement

PULLREVIEW

Have feelings

Know when to break the rules

Have fun.

Primelearn.thoughtbot.com/prime

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