In Ruby 2.5 and prior:

It’s been a longstanding rule in Ruby that you must use a capital ASCII letter as the first character of a Class or Module name. This limited you to just these 26 characters:

ABCDEFGHIJKLMNOPQRSTUVWXYZ

New in Ruby 2.6:

In Ruby 2.6, non-ASCII upper case characters are allowed. By my count, that makes a total of 1,853 options! Here are the 1,827 new characters that can start a Class or Module name in Ruby 2.6:

ÀÁÂÃÄÅÆÇÈÉÊËÌÍÎÏÐÑÒÓÔÕÖØÙÚÛÜÝÞĀĂĄĆĈĊČĎĐĒĔĖĘĚĜĞĠĢĤĦĨĪĬĮİIJĴĶĹĻĽĿŁŃŅŇŊŌŎŐŒŔŖŘŚŜŞŠŢŤŦŨŪŬŮŰŲŴŶŸŹŻŽƁƂƄƆƇƉƊƋƎƏƐƑƓƔƖƗƘƜƝƟƠƢƤƦƧƩƬƮƯƱƲƳƵƷƸƼDŽDžLJLjNJNjǍǏǑǓǕǗǙǛǞǠǢǤǦǨǪǬǮDZDzǴǶǷǸǺǼǾȀȂȄȆȈȊȌȎȐȒȔȖȘȚȜȞȠȢȤȦȨȪȬȮȰȲȺȻȽȾɁɃɄɅɆɈɊɌɎͰͲͶͿΆΈΉΊΌΎΏΑΒΓΔΕΖΗΘΙΚΛΜΝΞΟΠΡΣΤΥΦΧΨΩΪΫϏϒϓϔϘϚϜϞϠϢϤϦϨϪϬϮϴϷϹϺϽϾϿЀЁЂЃЄЅІЇЈЉЊЋЌЍЎЏАБВГДЕЖЗИЙКЛМНОПРСТУФХЦЧШЩЪЫЬЭЮЯѠѢѤѦѨѪѬѮѰѲѴѶѸѺѼѾҀҊҌҎҐҒҔҖҘҚҜҞҠҢҤҦҨҪҬҮҰҲҴҶҸҺҼҾӀӁӃӅӇӉӋӍӐӒӔӖӘӚӜӞӠӢӤӦӨӪӬӮӰӲӴӶӸӺӼӾԀԂԄԆԈԊԌԎԐԒԔԖԘԚԜԞԠԢԤԦԨԪԬԮԱԲԳԴԵԶԷԸԹԺԻԼԽԾԿՀՁՂՃՄՅՆՇՈՉՊՋՌՍՎՏՐՑՒՓՔՕՖႠႡႢႣႤႥႦႧႨႩႪႫႬႭႮႯႰႱႲႳႴႵႶႷႸႹႺႻႼႽႾႿჀჁჂჃჄჅჇჍᎠᎡᎢᎣᎤᎥᎦᎧᎨᎩᎪᎫᎬᎭᎮᎯᎰᎱᎲᎳᎴᎵᎶᎷᎸᎹᎺᎻᎼᎽᎾᎿᏀᏁᏂᏃᏄᏅᏆᏇᏈᏉᏊᏋᏌᏍᏎᏏᏐᏑᏒᏓᏔᏕᏖᏗᏘᏙᏚᏛᏜᏝᏞᏟᏠᏡᏢᏣᏤᏥᏦᏧᏨᏩᏪᏫᏬᏭᏮᏯᏰᏱᏲᏳᏴᏵḀḂḄḆḈḊḌḎḐḒḔḖḘḚḜḞḠḢḤḦḨḪḬḮḰḲḴḶḸḺḼḾṀṂṄṆṈṊṌṎṐṒṔṖṘṚṜṞṠṢṤṦṨṪṬṮṰṲṴṶṸṺṼṾẀẂẄẆẈẊẌẎẐẒẔẞẠẢẤẦẨẪẬẮẰẲẴẶẸẺẼẾỀỂỄỆỈỊỌỎỐỒỔỖỘỚỜỞỠỢỤỦỨỪỬỮỰỲỴỶỸỺỼỾἈἉἊἋἌἍἎἏἘἙἚἛἜἝἨἩἪἫἬἭἮἯἸἹἺἻἼἽἾἿὈὉὊὋὌὍὙὛὝὟὨὩὪὫὬὭὮὯᾈᾉᾊᾋᾌᾍᾎᾏᾘᾙᾚᾛᾜᾝᾞᾟᾨᾩᾪᾫᾬᾭᾮᾯᾸᾹᾺΆᾼῈΈῊΉῌῘῙῚΊῨῩῪΎῬῸΌῺΏῼℂℇℋℌℍℐℑℒℕℙℚℛℜℝℤΩℨKÅℬℭℰℱℲℳℾℿⅅⅠⅡⅢⅣⅤⅥⅦⅧⅨⅩⅪⅫⅬⅭⅮⅯↃⒶⒷⒸⒹⒺⒻⒼⒽⒾⒿⓀⓁⓂⓃⓄⓅⓆⓇⓈⓉⓊⓋⓌⓍⓎⓏⰀⰁⰂⰃⰄⰅⰆⰇⰈⰉⰊⰋⰌⰍⰎⰏⰐⰑⰒⰓⰔⰕⰖⰗⰘⰙⰚⰛⰜⰝⰞⰟⰠⰡⰢⰣⰤⰥⰦⰧⰨⰩⰪⰫⰬⰭⰮⱠⱢⱣⱤⱧⱩⱫⱭⱮⱯⱰⱲⱵⱾⱿⲀⲂⲄⲆⲈⲊⲌⲎⲐⲒⲔⲖⲘⲚⲜⲞⲠⲢⲤⲦⲨⲪⲬⲮⲰⲲⲴⲶⲸⲺⲼⲾⳀⳂⳄⳆⳈⳊⳌⳎⳐⳒⳔⳖⳘⳚⳜⳞⳠⳢⳫⳭⳲꙀꙂꙄꙆꙈꙊꙌꙎꙐꙒꙔꙖꙘꙚꙜꙞꙠꙢꙤꙦꙨꙪꙬꚀꚂꚄꚆꚈꚊꚌꚎꚐꚒꚔꚖꚘꚚꜢꜤꜦꜨꜪꜬꜮꜲꜴꜶꜸꜺꜼꜾꝀꝂꝄꝆꝈꝊꝌꝎꝐꝒꝔꝖꝘꝚꝜꝞꝠꝢꝤꝦꝨꝪꝬꝮꝹꝻꝽꝾꞀꞂꞄꞆꞋꞍꞐꞒꞖꞘꞚꞜꞞꞠꞢꞤꞦꞨꞪꞫꞬꞭꞮꞰꞱꞲꞳꞴꞶ???????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????ＡＢＣＤＥＦＧＨＩＪＫＬＭＮＯＰＱＲＳＴＵＶＷＸＹＺ (Characters unsupported by this font appear as squares.)

This change supports upper case characters in other languages but doesn’t go so far as to allow emoji as a Class or Module name. These examples are now valid Ruby:

class ?
end

?.new
#<?:0x...>

class Ωμέγα; end

Ωμέγα.new
#<Ωμέγα:0x...>

class Ærbødig; end

Ærbødig.new
#=> #<Ærbødig:0x...>

class Даймон; end

Даймон.new
#<Даймон:0x...>

It’s worth noting that local variables in Ruby could begin with these characters in Ruby 2.5 and earlier. (Thanks to Cary Swoveland for pointing this out.) A local variable starting with one of these characters would become a constant in Ruby 2.6.

Why support these additional characters? Sergei Borodanov started an issue ticket asking about support for Cyrillic characters. Matz decided, “maybe it’s time to relax the limitation for Non-ASCII capital letters to start constant names.” Nobuyoshi (“nobu”) Nakada (a.k.a. “patch monster”) wrote and committed the patch to support this new feature.

With the addition of this feature, Rubyists in various languages can use their own alphabet for the first character of a Class or Module. For example, a Greek Rubyist can now have an Ωμέγα class, instead of an Oμέγα class — where the first letter is transliterated. Thanks to the Ruby core team for making this change! It will be shipped on December 25, 2018 with Ruby 2.6.

We use Ruby for lots of things here at Square — including our Square Connect Ruby SDKs and open source Ruby projects. We’re eagerly awaiting the release of Ruby 2.6!

The Ruby logo is Copyright © 2006, Yukihiro Matsumoto, distributed under CC BY-SA 2.5.

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By Shannon Skipper
Medium