Single File Ruby Programs

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SINGLE FILE RUBY SINGLE FILE RUBY PROGRAMS PROGRAMS CHRISTIAN BÄUERLEIN CHRISTIAN BÄUERLEIN Created: 2020-03-26 Thu 18:58 1

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WELCOME! WELCOME! 2 . 1

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THE LOST ART OF SINGLE FILE RUBY PROGRAMS THE LOST ART OF SINGLE FILE RUBY PROGRAMS A loose collec on of Ruby fun facts and examples to organize your code in a single ﬁle. Let's have some fun with Ruby! 2 . 2

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CODE & TESTS IN ONE FILE CODE & TESTS IN ONE FILE 3 . 1

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RUBY MAGIC CONSTANTS RUBY MAGIC CONSTANTS There is ~$0. Source: Contains the name of the file containing the Ruby script being executed. Pre-defined variables and constants Pre-defined variables and constants 3 . 2

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THE SOURCE FILE THE SOURCE FILE def greet(name) "Hello #{name}!" end # this will only run if the script was the main # not load'd or require'd if __FILE__ == $0 require "test/unit/assertions" include Test::Unit::Assertions assert_equal 'Hello Ruby', greet('Ruby'), "greet function shoul end 3 . 3

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WHEN CALLED DIRECTLY WHEN CALLED DIRECTLY $ ruby code_and_test.rb greet function should return 'Hello Ruby!'. (Test::Unit::Asserti <"Hello Ruby"> expected but was <"Hello Ruby!">. diff: - Hello Ruby + Hello Ruby! ? 3 . 4

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WHEN REQUIRED WHEN REQUIRED require './code_and_test.rb' puts greet "Christian" $ ruby code_and_test_usage.rb Hello Christian! 3 . 5

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YOU MAY KNOW THIS FROM PYTHON YOU MAY KNOW THIS FROM PYTHON Source: def hello(): print("Hello world, this script was called!") if __name__ == '__main__': hello() Python Deﬁne Unit Test Classes Together with Code Python Deﬁne Unit Test Classes Together with Code 3 . 6

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A WEBSERVER IN ONE FILE? A WEBSERVER IN ONE FILE? 4 . 1

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MY LIFE BEFORE RUBY MY LIFE BEFORE RUBY Before Ruby, my favorite web framework was . Security ﬁrst: One index.html ﬁle in EVERY folder. CodeIgniter CodeIgniter 4 . 2

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SINATRA 0.6 SINATRA 0.6 sudo gem install sinatra 4 . 3

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Awesome!!! require "rubygems" require "sinatra" get '/' do "Hello World" end 4 . 4

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ruby myapp.rb 4 . 5

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TEMPLATES: UNCOOL WAY TEMPLATES: UNCOOL WAY "You can do this too but it's not as cool" - Sinatra Readme template :index do '%div.title Hello World!' end 4 . 6

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TEMPLATES TEMPLATES As documented in the this was the cool way to do it. README.rdoc README.rdoc get '/' do haml :index end use_in_file_templates! __END__ @@ layout X = yield X @@ index %div.title Hello world!!!!! 4 . 7

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A LITTLE RUBY HISTORY A LITTLE RUBY HISTORY 5 . 1

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RUBY IS A BETTER PERL RUBY IS A BETTER PERL Why the name 'Ruby'? Source: Inﬂuenced by Perl, Matz wanted to use a jewel name for his new language, so he named Ruby a er a colleague's birthstone. The Ruby Language FAQ The Ruby Language FAQ 5 . 2

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PERL'S LEGACY PERL'S LEGACY Ruby took a lot of things from Pearl. Today we will learn about: Keywords Command line ﬂags 5 . 3

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LET'S START WITH PERLDATA LET'S START WITH PERLDATA Perl has two special literals: __END__ - Indicates the logical end of the script before the actual end of ﬁle. Any following text is ignored. __DATA__ - A ﬁlehandle that points to everything that comes a er __END__. Source: perldata - perldoc.perl.org perldata - perldoc.perl.org 5 . 4

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THE THE __END__ __END__ AND AND DATA DATA KEYWORDS KEYWORDS Denotes the end of the regular source code sec on of a program ﬁle. Lines below __END__ will not be executed. 6 . 1

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Source: Those lines will be available via the special ﬁlehandle DATA Class: Object Class: Object 6 . 2

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SIMPLE EXAMPLE SIMPLE EXAMPLE DATA.each_line do |line| puts line end __END__ Doom Quake Diablo 6 . 3

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ERB TEMPLATE AND CODE IN ONE FILE ERB TEMPLATE AND CODE IN ONE FILE require 'erb' time = Time.now renderer = ERB.new(DATA.read) puts renderer.result() __END__ The current time is <%= time %>. 6 . 4

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EXPLAINED: SINATRA STYLE MULTIPLE TEMPLATES IN FILE EXPLAINED: SINATRA STYLE MULTIPLE TEMPLATES IN FILE get '/' do haml :index end use_in_file_templates! __END__ @@ layout X = yield X @@ index %div.title Hello world!!!!! 6 . 5

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Source: File.read(caller.first.split(":").first).split("__END__", 2).last Mixing code and data in Ruby Mixing code and data in Ruby 6 . 6

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PSA: PHP CAN DO IT AS WELL PSA: PHP CAN DO IT AS WELL Source: Example: // open self $fp = fopen(__FILE__, 'rb'); // seek file pointer to data //__COMPILER_HALT_OFFSET__ will return //the point after __halt_compiler(); fseek($fp, __COMPILER_HALT_OFFSET__); // and output it $unpacked = gzinflate(stream_get_contents($fp)); __halt_compiler(); //now here... all the binary gzdeflate already items!!! PHP: __halt_compiler - Manual PHP: __halt_compiler - Manual __halt_compiler(), make install ﬁles for PHP smaller __halt_compiler(), make install ﬁles for PHP smaller 6 . 7

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BUNDLER INLINE BUNDLER INLINE Fun fact: You don't need a Gemfile to use bundler! Useful for scripts in your /utils folder that you only use once a year. Source: How to use Bundler in a single-ﬁle Ruby script How to use Bundler in a single-ﬁle Ruby script 7 . 1

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INLINE HTTPARTY INLINE HTTPARTY require 'bundler/inline' gemfile do gem 'httparty' end puts HTTParty.get('https://www.boredapi.com/api/activity') 7 . 2

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INLINE MINITEST INLINE MINITEST require 'bundler/inline' gemfile do gem 'minitest', require: false end require 'minitest/autorun' class MyTest < Minitest::Test def test_should_be_true assert_equal true, true end end 7 . 3

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ADVANCED EXAMPLE: DOWNLOAD ICAL TO ADVANCED EXAMPLE: DOWNLOAD ICAL TO ORG ORG Source: ical_to_org.rb ical_to_org.rb 8 . 1

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ADVANCED EXAMPLE: DOWNLOAD ICAL TO ADVANCED EXAMPLE: DOWNLOAD ICAL TO ORG ORG Install Dependencies Source: ical_to_org.rb ical_to_org.rb 8 . 1

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ADVANCED EXAMPLE: DOWNLOAD ICAL TO ADVANCED EXAMPLE: DOWNLOAD ICAL TO ORG ORG Install Dependencies Do stuﬀ (download calendar events) Source: ical_to_org.rb ical_to_org.rb 8 . 1

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ADVANCED EXAMPLE: DOWNLOAD ICAL TO ADVANCED EXAMPLE: DOWNLOAD ICAL TO ORG ORG Install Dependencies Do stuﬀ (download calendar events) Render to ERb template Source: ical_to_org.rb ical_to_org.rb 8 . 1

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BEGIN BEGIN AND AND END END KEYWORDS KEYWORDS Yes, this is taken from Perl as well. 9 . 1

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DEFINITION DEFINITION Source: BEGIN defines a block that is run before any other code in the current file. It is typically used in one-liners with ruby -e. Similarly END defines a block that is run a er any other code. Documenta on for Ruby 2.2.0 Documenta on for Ruby 2.2.0 9 . 2

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EXAMPLE EXAMPLE END { puts 3 } BEGIN { puts 1 } puts 2 ruby begin.rb 1 2 3 9 . 3

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INTRODUCING LRUBY INTRODUCING LRUBY Logging Ruby - The Ruby alias for the forge ul scripter Logging Ruby! Only Feature: No more scrolling through your terminal… Logs the output of a script to the script itself! 10 . 1

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LET'S TRY THIS OUT LET'S TRY THIS OUT cat log_results/hello_world.rb ruby log_results/hello_world.rb 10 . 2

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INTRODUCING: LRUBY INTRODUCING: LRUBY lruby log_results/hello_world.rb cat log_results/hello_world.rb 10 . 3

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HOW DOES IT WORK? HOW DOES IT WORK? Let's check out the source of which lruby LRuby log_results.rb LRuby log_results.rb 10 . 4

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THE GARBAGE FLAG THE GARBAGE FLAG Aaaaand back to Perl! 11 . 1

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PERLRUN PERLRUN Source: perl -x Leading garbage will be discarded un l the ﬁrst line that starts with #! and contains the string "perl". perlrun - perldoc.perl.org perlrun - perldoc.perl.org 11 . 2

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BUT… WHY? BUT… WHY? Tells Perl that the program is embedded in a larger chunk of unrelated text, such as in a mail message. 11 . 3

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AND IN RUBY.. AND IN RUBY.. Source: ruby -x Tells Ruby that the script is embedded in a message. Leading garbage will be discarded un l the ﬁrst that starts with "#!" and contains string "ruby". Ruby Docs Command line Op ons Ruby Docs Command line Op ons 11 . 4

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EXAMPLE EXAMPLE Hello dear friend, this is a mail message. Please execute it with your ruby interpre Thanks, a random stranger #! hahaha this is ruby now puts "Hello World" ruby -x email.eml 11 . 5

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A SELF-ANIMATING GIF A SELF-ANIMATING GIF This is not an animated gif, but a gif that animates itself. 12 . 1

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LET'S TALK ABOUT GIFS LET'S TALK ABOUT GIFS 12 . 2

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A GIF FILE CONSISTS OF BLOCKS A GIF FILE CONSISTS OF BLOCKS 12 . 3

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EXAMPLE EXAMPLE 12 . 4

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TERMINATOR BYTE TERMINATOR BYTE The trailer block indicates when you've reached the end of the ﬁle. It is always a byte with a value of 3B. Source: What's In A GIF What's In A GIF 12 . 5

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SOOOO NOW WE KNOW THAT.. SOOOO NOW WE KNOW THAT.. 12 . 6

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SOOOO NOW WE KNOW THAT.. SOOOO NOW WE KNOW THAT.. GIFs are nice 12 . 6

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SOOOO NOW WE KNOW THAT.. SOOOO NOW WE KNOW THAT.. GIFs are nice GIFs always end with the same terminator byte 12 . 6

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SOOOO NOW WE KNOW THAT.. SOOOO NOW WE KNOW THAT.. GIFs are nice GIFs always end with the same terminator byte Ruby is nice 12 . 6

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SOOOO NOW WE KNOW THAT.. SOOOO NOW WE KNOW THAT.. GIFs are nice GIFs always end with the same terminator byte Ruby is nice Ruby can start with a deﬁned start line 12 . 6

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SOOOO NOW WE KNOW THAT.. SOOOO NOW WE KNOW THAT.. GIFs are nice GIFs always end with the same terminator byte Ruby is nice Ruby can start with a deﬁned start line Nice. 12 . 6

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A SELF-ANIMATING GIF A SELF-ANIMATING GIF This is not an animated gif, but a gif that animates itself. 12 . 7

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A SELF-ANIMATING GIF A SELF-ANIMATING GIF This is not an animated gif, but a gif that animates itself. One ﬁle 12 . 7

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A SELF-ANIMATING GIF A SELF-ANIMATING GIF This is not an animated gif, but a gif that animates itself. One ﬁle Upper half is a GIF 12 . 7

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A SELF-ANIMATING GIF A SELF-ANIMATING GIF This is not an animated gif, but a gif that animates itself. One ﬁle Upper half is a GIF Lower half is Ruby code 12 . 7

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A SELF-ANIMATING GIF A SELF-ANIMATING GIF This is not an animated gif, but a gif that animates itself. One ﬁle Upper half is a GIF Lower half is Ruby code File rewrites itself! 12 . 7

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A SELF-ANIMATING GIF A SELF-ANIMATING GIF This is not an animated gif, but a gif that animates itself. One ﬁle Upper half is a GIF Lower half is Ruby code File rewrites itself! Proﬁt! 12 . 7

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SOURCE CODE SOURCE CODE Let's check out the together! rbgif.gif source code rbgif.gif source code 12 . 8

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LIVE DEMO! LIVE DEMO! while 1; do cd ~/Dropbox/slides/single-file-ruby-programs/rbgif; 12 . 9

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ONE MORE THING… ONE MORE THING… Source: #!/bin/sh echo This is bash i=12 echo $i perl - $i <<'__HERE__' my $i = shift; print "This is perl\n"; print ++$i . "\n"; __HERE__ echo This is bash again echo $i perl script inside a shell script perl script inside a shell script 13 . 1

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PERLMONKS.ORG 2000 TESTIMONIALS PERLMONKS.ORG 2000 TESTIMONIALS 13 . 2

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PERLMONKS.ORG 2000 TESTIMONIALS PERLMONKS.ORG 2000 TESTIMONIALS "Ain't that fun?" - dchetlin 13 . 2

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PERLMONKS.ORG 2000 TESTIMONIALS PERLMONKS.ORG 2000 TESTIMONIALS "Ain't that fun?" - dchetlin "It's strange and terrible and I'm not sure how to get something out of the perl part, but this sort of works" - eg "This, on the other hand is just … just .. well, I don't know. Not right. Not even wrong. It just is." - Blue 13 . 2

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SUMMARY SUMMARY 14 . 1

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RUBY IS FUN! RUBY IS FUN! 14 . 2

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SINGLE FILE RUBY PROGRAMS SINGLE FILE RUBY PROGRAMS Code & Tests Dependencies & Code Data & Code Code & Data Code & Output Try it out for fun and proﬁt! 14 . 3

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THANKS! THANKS! Ques ons? Chris an Bäuerlein @fabrik42 @fabrik42 15 . 1