Structure and Interpretation of Ruby Programs

A lightning talk about how to structure one-off scripts that don't turn into a huge mess as features are added.

Transcript

1. Tim Uruski
   Clio and YYC Ruby
   @timuruski
   

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2. Structure and
   Interpretation of
   Computer Programs
   Ruby
   

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3. "I need you to
   export some data."
   

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4. #!/usr/bin/env ruby
   require 'cheezburger'
   db = DatabaseWrapper.default_connection
   user_id = ARGV.shift
   locations = LocationStream.new(db, user_id)
   puts locations
   

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5. "Actually I need it
   formatted as JSON."
   

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6. #!/usr/bin/env ruby
   require 'cheezburger'
   require 'json'
   db = DatabaseWrapper.default_connection
   user_id = ARGV.shift
   locations = LocationStream.new(db, user_id)
   geojson = {
   "type" => "FeatureCollection",
   "features" => locations.map { |location|
   {
   "type" => "Feature",
   "geometry" => {
   "type" => "Point",
   "coordinates" => [location.lng, location.lat]
   }
   "properties" => {
   "name": "location.name"
   }
   }
   }
   }
   end
   print JSON.pretty_generate(geojson)
   

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7. "Can you filter it
   by date range?"
   

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8. #!/usr/bin/env ruby
   require 'cheezburger'
   require 'json'
   db = DatabaseWrapper.default_connection
   user_id = ARGV.shift
   query_date = ARGV.shift || Tume.now
   min_recorded_at = query_date.beginning_of_day.utc.to_i * 1000
   max_recorded_at = query_date.end_of_day.utc.to_i * 1000
   query = {
   order_by: 'recorded_at',
   start_at: min_recorded_at,
   end_at: end_recorded_at
   }
   locations = LocationStream.new(db, user_id, query)
   geojson = {
   "type" => "FeatureCollection",
   "features" => locations.map { |location|
   {
   "type" => "Feature",
   "geometry" => {
   "type" => "Point",
   "coordinates" => [location.lng, location.lat]
   }
   "properties" => {
   "name": "location.name"
   }
   }
   }
   }
   end
   print JSON.pretty_generate(geojson)
   

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9. "We also need the data
   from other environments."
   

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10. #!/usr/bin/env ruby
    require 'cheezburger'
    require 'json'
    if database_url = ENV.fetch('DATABASE_URL')
    db = DatabaseWrapper.new(database_url)
    else
    db = DatabaseWrapper.default_connection
    end
    user_id = ARGV.shift
    query_date = ARGV.shift || Tume.now
    min_recorded_at = query_date.beginning_of_day.utc.to_i * 1000
    max_recorded_at = query_date.end_of_day.utc.to_i * 1000
    query = {
    order_by: 'recorded_at',
    start_at: min_recorded_at,
    end_at: end_recorded_at
    }
    locations = LocationStream.new(db, user_id, query)
    geojson = {
    "type" => "FeatureCollection",
    "features" => locations.map { |location|
    {
    "type" => "Feature",
    "geometry" => {
    "type" => "Point",
    "coordinates" => [location.lng, location.lat]
    }
    "properties" => {
    "name": "location.name"
    }
    }
    }
    }
    end
    print JSON.pretty_generate(geojson)
    

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11. "Can I just give you
    the user's email address
    instead of that weird ID?"
    

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12. #!/usr/bin/env ruby
    require 'cheezburger'
    require 'json'
    if database_url = ENV.fetch('DATABASE_URL')
    db = DatabaseWrapper.new(database_url)
    else
    db = DatabaseWrapper.default_connection
    end
    identifier = ARGV.shift
    begin
    user = UserStore.new(db).find(identifier)
    rescue NoUserFound
    warn "No user found for #{identifier}"
    exit 1
    end
    query_date = ARGV.shift || Tume.now
    min_recorded_at = query_date.beginning_of_day.utc.to_i * 1000
    max_recorded_at = query_date.end_of_day.utc.to_i * 1000
    query = {
    order_by: 'recorded_at',
    start_at: min_recorded_at,
    end_at: end_recorded_at
    }
    locations = LocationStream.new(db, user.id, query)
    geojson = {
    "type" => "FeatureCollection",
    "features" => locations.map { |location|
    {
    "type" => "Feature",
    "geometry" => {
    "type" => "Point",
    "coordinates" => [location.lng, location.lat]
    }
    "properties" => {
    "name": "location.name"
    }
    }
    }
    }
    end
    print JSON.pretty_generate(geojson)
    

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13. "Can you also filter
    by X, Y and Z fields?"
    

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14. #!/usr/bin/env ruby
    require 'cheezburger'
    require 'json'
    window_size = 10
    stay_radius = 500
    activity_threshold = 2.5
    OptionParser.new do |opts|
    window_desc = 'Window size in minutes, default: 5'
    opts.on('-wSIZE', '--window=SIZE', window_desc, Integer) do |value|
    window_size = value * 60
    end
    activity_desc = 'Activity within window threshold, default: 23'
    opts.on('-aCOUNT', '--activity=COUNT', activity_desc, Integer) do |value|
    activity_threshold = value
    end
    radius_desc = 'Size of stay radius in metres, default: 50.0'
    opts.on('-rSIZE', '--radiusSIZE', radius_desc, Float) do |value|
    stay_radius = value
    end
    end.parse!
    if database_url = ENV.fetch('DATABASE_URL')
    db = DatabaseWrapper.new(database_url)
    else
    db = DatabaseWrapper.default_connection
    end
    identifier = ARGV.shift
    begin
    user = UserStore.new(db).find(identifier)
    rescue NoUserFound
    warn "No user found for #{identifier}"
    exit 1
    end
    query_date = ARGV.shift || Tume.now
    min_recorded_at = query_date.beginning_of_day.utc.to_i * 1000
    max_recorded_at = query_date.end_of_day.utc.to_i * 1000
    query = {
    order_by: 'recorded_at',
    start_at: min_recorded_at,
    end_at: end_recorded_at
    }
    locations = LocationStream.new(db, user.id, query)
    geojson = {
    "type" => "FeatureCollection",
    "features" => locations.map { |location|
    {
    "type" => "Feature",
    "geometry" => {
    "type" => "Point",
    "coordinates" => [location.lng, location.lat]
    }
    "properties" => {
    "name": "location.name"
    }
    }
    }
    }
    end
    print JSON.pretty_generate(geojson)
    

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15. "How do I use that script
    you wrote for exports?"
    

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16. #!/usr/bin/env ruby
    require 'json'
    require 'optparse'
    require 'bundler/setup'
    require 'active_support'
    require 'active_support/core_ext/time'
    require_relative '../lib/cheezburger'
    include Cheezburger
    window_size = 10
    stay_radius = 500
    activity_threshold = 2.5
    OptionParser.new do |opts|
    window_desc = 'Window size in minutes, default: 5'
    opts.on('-wSIZE', '--window=SIZE', window_desc, Integer) do |value|
    window_size = value * 60
    end
    activity_desc = 'Activity within window threshold, default: 23'
    opts.on('-aCOUNT', '--activity=COUNT', activity_desc, Integer) do |value|
    activity_threshold = value
    end
    radius_desc = 'Size of stay radius in metres, default: 50.0'
    opts.on('-rSIZE', '--radiusSIZE', radius_desc, Float) do |value|
    stay_radius = value
    end
    end.parse!
    if ARGV.empty?
    warn "Usage: [DATABASE_URL=] #{$0} [2016-02-01]"
    exit 1
    end
    user_id = args.shift
    date = args.shift
    database_url = ENV.fetch('DATABASE_URL')
    database = DatabaseWrapper.new(database_url)
    def find_user(database, identifier)
    begin
    user = UserStore.new(database).find(identifier)
    rescue NoUserFound
    warn "No user found for #{identifier}"
    exit 1
    end
    end
    def fetch_locations(database, user, query_date)
    min_recorded_at = query_date.beginning_of_day.utc.to_i * 1000
    max_recorded_at = query_date.end_of_day.utc.to_i * 1000
    query = { order_by: 'recorded_at', start_at: min_recorded_at, end_at: end_recorded_at }
    begin
    LocationStream.new(database, user, query)
    rescue NoLocationsFound
    export_date = query_date.strftime('%Y-%m-%d')
    warn "No locations found for #{export_date}"
    exit 1
    end
    end
    def to_coords(location)
    [location.lng, location.lat]
    end
    user = find_user(database, options[:user_id])
    query_date = options[:date] ? Time.parse(options[:date]) : Time.now
    locations = fetch_locations(database, user, query_date)
    geojson = {
    "type" => "FeatureCollection",
    "features" => locations.map { |location|
    {
    "type" => "Feature",
    "geometry" => {
    "type" => "Point",
    "coordinates" => coords(location)
    }
    "properties" => {
    "name": "location.name"
    }
    }
    }
    }
    end
    print JSON.pretty_generate(geojson)
    

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17. "One more thing..."
    

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18. Time to refactor
    

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19. "I'll extract some methods,
    that's a good trick!"
    

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20. Execution
    Dependency
    

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21. Inverted Pyramid
    Headline
    Who? What? Where? When?
    Background Details
    General Info
    

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22. Execution
    

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23. Execution
    Dependency
    

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24. at_exit do
    # script goes here
    end
    

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25. at_exit do
    opts = parse_opts
    result = frobulate(opts)
    puts result
    end
    

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26. 1.Wrap the script core in at_exit
    2.Organize dependencies downwards
    3.Parse options in one place
    

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27. Example
    

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28. #!/usr/bin/env ruby
    puts "Hello, #{ARGV.shift || 'world'}"
    

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29. #!/usr/bin/env ruby
    require 'optparse'
    name = 'world'
    OptionParser.new do |opts|
    opts.on('-n=NAME', '--name=NAME', 'Name to greet') do |value|
    name = value
    end
    end.parse!
    puts "Hello, #{name}"
    

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30. #!/usr/bin/env ruby
    require 'optparse'
    def greet(name)
    puts "Hello, #{name}"
    end
    options = {
    name: 'world'
    }
    OptionParser.new do |opts|
    opts.on('-n=NAME', '--name=NAME', 'Name to greet') do |value|
    options[:name] = value
    end
    end.parse!
    greet(options[:name])
    

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31. #!/usr/bin/env ruby
    require 'optparse'
    def greet(name)
    puts "Hello, #{name}"
    end
    options = {
    name: 'world'
    }
    OptionParser.new do |opts|
    opts.on('-n=NAME', '--name=NAME', 'Name to greet') do |value|
    options[:name] = value
    end
    end.parse!
    greet(options[:name])
    

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32. #!/usr/bin/env ruby
    require 'optparse'
    at_exit do
    options = parse_options
    greet(options[:name])
    end
    def parse_options(args = ARGV)
    {
    name: 'world'
    }.tap do |options|
    parser = OptionParser.new do |opts|
    opts.on('-n=NAME', '--name=NAME', 'Name to greet', String) do |value|
    options[:name] = value
    end
    end
    parser.parse!(args)
    end
    end
    def greet(name)
    puts "Hello, #{name}"
    end
    

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33. #!/usr/bin/env ruby
    require 'optparse'
    at_exit do
    options = parse_options
    greet(options[:name])
    end
    def parse_options(args = ARGV)
    {
    name: 'world'
    }.tap do |options|
    parser = OptionParser.new do |opts|
    opts.on('-n=NAME', '--name=NAME', 'Name to greet', String) do |value|
    options[:name] = value
    end
    end
    parser.parse!(args)
    end
    end
    def greet(name)
    puts "Hello, #{name}"
    end
    

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34. #!/usr/bin/env ruby
    require 'optparse'
    at_exit do
    options = parse_options
    greet(options[:name])
    end
    def parse_options(args = ARGV)
    {
    name: 'world'
    }.tap do |options|
    parser = OptionParser.new do |opts|
    opts.on('-n=NAME', '--name=NAME', 'Name to greet', String) do |value|
    options[:name] = value
    end
    end
    parser.parse!(args)
    end
    end
    def greet(name)
    puts "Hello, #{name}"
    end
    

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35. 1.Wrap the script core in at_exit
    2.Organize dependencies downwards
    3.Parse options in one place
    

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36. Confident Ruby
    http://confidentruby.com/
    

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37. Structuring Ruby Scripts
    http://timuruski.net/blog/2016/structuring-ruby-scripts/
    

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38. Helpful Gist
    https://git.io/sirp
    

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