Functional Ruby Idioms

Method Chaining

Method chaining passes each result into the next method call.

method chain A method chain reads left to right when each step returns a value for the next step.

Method Chaining

raw_text
method_chaining.rb
Replay: real traced execution (multi-file project)
raw_text = " ruby "

cleaned = raw_text.strip
normalized = cleaned.downcase
title = normalized.capitalize
label = title.then { |text| "Topic: #{text}" }

puts "raw=#{raw_text}"
puts "cleaned=#{cleaned}"
puts "label=#{label}"

raw_text = " trace "

cleaned = raw_text.strip
normalized = cleaned.downcase
title = normalized.capitalize
label = title.then { |text| "Topic: #{text}" }

puts "raw=#{raw_text}"
puts "cleaned=#{cleaned}"
puts "label=#{label}"

raw_text = " CODE "

cleaned = raw_text.strip
normalized = cleaned.downcase
title = normalized.capitalize
label = title.then { |text| "Topic: #{text}" }

puts "raw=#{raw_text}"
puts "cleaned=#{cleaned}"
puts "label=#{label}"

  1. raw_text ← ruby , cleaned ← ruby, normalized ← ruby, title ← Ruby

    1raw_text→  ruby  = " ruby "  #@raw_text=" trace ", " CODE "23cleaned→ ruby = raw_text.stripruby4normalized→ ruby = cleaned.downcaseruby5title→ Ruby = normalized.capitalizeRuby6label→ Topic: Ruby = titleRuby.then { |text| "Topic: #{text}" }78puts "raw=#{raw_text ruby }"9puts "cleaned=#{cleanedruby}"10puts "label=#{labelTopic: Ruby}"
    outputraw= ruby
cleaned=ruby
label=Topic: Ruby

  1. raw_text ← trace , cleaned ← trace, normalized ← trace, title ← Trace

    1raw_text→  trace  = " trace "23cleaned→ trace = raw_text.striptrace4normalized→ trace = cleaned.downcasetrace5title→ Trace = normalized.capitalizeTrace6label→ Topic: Trace = titleTrace.then { |text| "Topic: #{text}" }78puts "raw=#{raw_text trace }"9puts "cleaned=#{cleanedtrace}"10puts "label=#{labelTopic: Trace}"
    outputraw= trace
cleaned=trace
label=Topic: Trace

  1. raw_text ← CODE , cleaned ← CODE, normalized ← code, title ← Code

    1raw_text→  CODE  = " CODE "23cleaned→ CODE = raw_text.stripCODE4normalized→ code = cleaned.downcasecode5title→ Code = normalized.capitalizeCode6label→ Topic: Code = titleCode.then { |text| "Topic: #{text}" }78puts "raw=#{raw_text CODE }"9puts "cleaned=#{cleanedCODE}"10puts "label=#{labelTopic: Code}"
    outputraw= CODE
cleaned=CODE
label=Topic: Code