Ruby was initially designed to be a successor of the Perl programming language, which also means that it inherited a lot of Perl's expressiveness. To celebrate this, the TRIC¹ contest was invented: Write the most Transcendental, Imbroglio Ruby program! Illustrate some of the subtleties (and design i...

Have you ever been confused by the __underscores__ required by some of __RUBY__'s features? You can get it right with this overview of all of "super snake" keywords and methods. There are three different types of underscore-wrapped syntaxes in the Ruby core language: keywords Object methods and Kern...

The Ruby core team cares a lot about Unicode, and this is why we have pretty good Unicode support in the language. Even though the Unicode standard evolves constantly - it gets updated at least once a year - Ruby's Unicode support is often only a little bit behind the current version of Unicode. The...

Recent Ruby versions allow you to choose from a wide-range of uppercase letters - beyond just ASCII - to start a constant / class name: class Österreich # 00D6 ├─ Ö ├─ LATIN CAPITAL LETTER O WITH DIAERESIS end # Syntax OK However, it is not possible to use just any Unicode character: class ℻ # 213B ...

Ruby's mode of operation can be altered with some --enable-* / --disable-* command-line switches. By default, all of the following features are activated, except for the frozen strings and the JIT: Feature CLI Option to Change Description RubyGems --disable-gems RubyGems is the package manager of Ru...

What is your wild guess: How many different ways does Ruby provide for inserting a NULL byte into a double-quoted string? There are exactly 43 options¹! Here is the list, put together with some ideas from Episode 61: Meta Escape Control: Directly embedded NULL byte # => "\u0000" "\0" # => "\u0000" "...

How does nothing (as in nil, null, or nan) compare to nothing? Equality Equality == nil 0 0.0 0i 0r NaN¹ nil true false false false false false 0 false true true true true false 0.0 false true true true true false 0i false true true true true false 0r false true true true true false NaN false false ...

The introduction of pattern matching in Ruby 2.7 brought us a new style of multi-assigning local variables: The pattern assignment, or, how you could also call it, the assignment in-style. After you have deactivated the warnings for experimental features, try the following piece of code: [1, 2, 3, 4...

Ruby's Warning module learned some new tricks in Ruby 2.7: Support for muting different categories of compile warnings has been introduced. This is a mechanism on top of the warning level reflected by the $VERBOSE variable. You can now silence deprecation warnings: These are aspects of the language ...

Ruby comes with good support for Unicode-related features. Read on if you want to learn more about important Unicode fundamentals and how to use them in Ruby… …or just watch my talk from RubyConf 2017: ⑩ Unicode Characters You Should Know About as a 👩‍💻 Ruby ♡ Unicode Characters in Unicode Codepoint...

Starting with Ruby 2.5¹ it is possible to customize the behavior of Kernel#warn through the Warning module. Here is how: def Warning.warn(w) # super calls the original behavior, which is printing to $stderr super "\e[31;1mRUBY WARNING: \e[22m#{w.sub(/warning: /, '')}\e[0m" end # # # # examples warn ...

Regexes, the go-to-mechanism for string matching, must not only be written, but also need to be applied. This episode acts as a reference with some style advice for working with regular expressions in Ruby. If you are looking for resources on writing the actual regexes, take a look at the link colle...

When you get farther upwards the steep hill that is Ruby mastery, you will come across some powerful, yet slightly evil methods: instance_eval and class_eval¹. They allow you to execute code and define methods tied to a specific class, at the same time giving you access to outer scope variables thro...

Ruby was created in 1993 and has come a long way. The preferred style of coding has changed quite a lot and solid best practice has emerged (though, as always, one size does not fit all). At the same time, Ruby's tool support could be better, the language is still too complex. Maybe, the time has co...

Double-quoted strings can not only be used with interpolation, #{}, they also support various escape sequences, which are initiated with \. Escape sequences allow you to embed raw byte and codepoint values. Furthermore, there are shortcuts for common formatting and control characters. Byte Sequences...

Ruby has more than one way to access additional information about the most recent regex match, like captured groups. One way is using the special variables $`, $&, $', $1 - $9, $+, and also in the MatchData object $~. They become available after using a method that matched a regex, or when the metho...

Ruby's big DATA constant does more than you might expect! Everything after the __END__ keyword (at the beginning of the line) is not interpreted as Ruby, but can be retrieved with the big¹ DATA constant.² This is an example big-data.rb script: p DATA.read __END__ big data Big DATA is a File object, ...

Ruby supports magic comments (interpreter instructions) at the top of the source file, mostly known for setting a source files' Encoding. This is the most common use case, but there is more you can do. Source File Encoding The default encoding of string literals in a Ruby file is UTF-8: p "".encodin...

%a %A %b %B %c %C %d %D %e %F %g %G %h %H %I %j %k %l %L %m %M %n %N %p %P %Q %r %R %s %S %t %T %u %U %v %V %w %W %x %X %y %Y %z %Z %+ %% - _ 0 ^ # : Date and time formatting is traditionally done with strftime. Not any different in Ruby, which includes a public domain based strftime implementation ...

How come that Ruby has two ASCII encodings? Encoding.name_list.grep(/ASCII/) # => ["ASCII-8BIT", "US-ASCII"] Which one is the normal one you should use for ASCII? Aliases ASCII-8BIT US-ASCII BINARY ASCII   ANSI_X3.4-1968   646 So, US-ASCII is aliased to ASCII, but then what is ASCII-8BIT for? Encodi...

Another of Ruby's idiosyncrasies is equalness. It's not too complicated, but naming is an issue here. Four Concepts of Equalness equal? Object Identity Comparison This one is easy. Two objects should be considered identical. Think: x.object_id == y.object_id == Equality Equality This is the usual me...

Similar to metaprogramming, Ruby's type conversion system has evolved over time. While the result functions, it is also a little inconsistent and suffers from poor naming. Let's put things in perspective: Implicit and Explicit Conversion Ruby objects are usually converted to other classes/types usin...

Generated with Ruby 3.2.2, including RubyGems and DidYouMean: Object (Class) ├─ARGF (ARGF.class) ├─ARGV (Array) ├─ArgumentError (Class) ├─Array (Class) ├─BasicObject (Class) │ └─BasicObject → BasicObject ├─Binding (Class) ├─CROSS_COMPILING (NilClass) ├─Class (Class) ├─ClosedQueueError (Class) ├─Comp...

It is less common, but similar to methods, constants have a visibility attached to them. You have the choice between private and public, and you can also mark a constant deprecated! Like with methods, the default visibility of a constant is public. Unlike methods, which have a lot of associated meth...

How many bytes (= ASCII characters) of Ruby code does it take to generate a SHA 256 hash sum of STDIN? 500 Bytes¹ q,z=[3,2].map{|t|i=l=1;(2..330).select{i-1<(l*=i)%i+=1}.map{|e|(e**t**-1*X=2**32).to_i&X-=1}} s=proc{|n,*m|a=0 m.map{|e|a^=n>>e|n<<32-e} a} i=$<.read.b<<128 (i+"\0"*(56.-(w=i.size)%64)+[...

Some words should not be chosen as identifiers for variables, parameters and methods in Ruby, because they clash with core methods or keywords. As long as you do not define a method with the name of a keyword, Ruby will not complain. Still, it is often better to avoid naming things like existing met...

%a %A %b %B %c %d %e %E %f %g %G %i %o %p %s %u %x %X %% 0 $ # + - * space Ruby comes with a structured alternative to classic string interpolation: This episode will explore format strings, also known as the sprintf syntax. Recall the normal way of interpolating variables into a string: v = 42 "-->...

Ruby was initially designed to be a successor of the Perl programming language, which also means that it inherited a lot of Perl's expressiveness. To celebrate this, the TRIC¹ contest was invented: Write the most Transcendental, Imbroglio Ruby program! Illustrate some of the subtleties (and design i...

Ruby was initially designed to be a successor of the Perl programming language, which also means that it inherited a lot of Perl's expressiveness. To celebrate this, the TRIC¹ contest was invented: Write the most Transcendental, Imbroglio Ruby program! Illustrate some of the subtleties (and design i...

There is nothing easier than parsing the command-line arguments given to your Ruby program: It is an array found in the special variable $*: $ ruby -e 'p $*' -- some command line --arguments ["some", "command", "line", "--arguments"] That is Too Easy! The trouble begins with supporting common argume...