twenty four merry days of Perl Feed

Where Does He Get Those Wonderful Codepoints?

App::Uni & Unicode::Tussle - 2011-12-24

𝔖𝔱𝔲𝔭𝔦𝔡 𝔘𝔫𝔦𝔠𝔬𝔡𝔢 𝔗𝔯𝔦𝔠𝔨𝔰

I got interested in understanding how Unicode works for two reasons: I needed to understand it to do my job, and it gave me an improved ability to do stupid things on Twitter. Mostly, today I want to talk about the latter.

So, for example, how did I make that stupid section header above? (By the way, if you can't read it, you should probably go install a more complete Unicode font, like Symbola!) Well, I knew that Unicode 6 had introduced Fraktur characters, and if I knew how they were named, I could start from there, so I used the uni command provided with App::Uni:


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$ uni fraktur
1D504 𝔄 MATHEMATICAL FRAKTUR CAPITAL A
1D505 𝔅 MATHEMATICAL FRAKTUR CAPITAL B
1D507 𝔇 MATHEMATICAL FRAKTUR CAPITAL D
1D508 𝔈 MATHEMATICAL FRAKTUR CAPITAL E
1D509 𝔉 MATHEMATICAL FRAKTUR CAPITAL F
1D50A 𝔊 MATHEMATICAL FRAKTUR CAPITAL G
...

 

This a stupidly useful tool for being a goofball. Did you know that I mostly use my programming skills to make dumb jokes on the internet? Yeah, this is your surprised face: 😐


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$ uni neutral
A64E Ꙏ CYRILLIC CAPITAL LETTER NEUTRAL YER
A64F ꙏ CYRILLIC SMALL LETTER NEUTRAL YER
1F610 😐 NEUTRAL FACE

 

The 𝑁𝑒𝑥𝑡 Level

So, uni is great for finding characters quickly by name. Sometimes, though, you want to find characters based on other criteria. For example, when I see somebody trying to use m{\d} to match ASCII digits, I want to give them an example of some of the things that they really don't think should be matched. Tom Christiansen is one of Perl's chief Unicode gurus, and he's written a bunch of weird and useful tools. brian d foy packaged those up and now it's easy for anybody to install them. One of the tools is unichars, which lets you find characters based on many more criteria than their names. For example, to enlighten the guy using m{\d}, I want to find digits that aren't in [0-9] and I'm going to pick the seven from each script, because seven is a funny number:


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$ unichars '\d' '$_ !~ /[0-9]/' 'NAME =~ /SEVEN/'
...
७ U+096D DEVANAGARI DIGIT SEVEN
৭ U+09ED BENGALI DIGIT SEVEN
੭ U+0A6D GURMUKHI DIGIT SEVEN
૭ U+0AED GUJARATI DIGIT SEVEN
୭ U+0B6D ORIYA DIGIT SEVEN
௭ U+0BED TAMIL DIGIT SEVEN
౭ U+0C6D TELUGU DIGIT SEVEN
೭ U+0CED KANNADA DIGIT SEVEN
൭ U+0D6D MALAYALAM DIGIT SEVEN
๗ U+0E57 THAI DIGIT SEVEN
໗ U+0ED7 LAO DIGIT SEVEN
...

 

I just specified my three criteria as arguments to the command:

  • a digit: \d

  • not in [0-9]: $_ !~ /[0-9]/

  • seven: NAME =~ /SEVEN/

You could also replace that second rule with, say, '\P{ASCII}'. There's more than one way to do it. There are some important things to know, though. By default, for example, unichars won't search the supplementary multilingual plane or the so-called "astral" plane. That means that this vital search will fail:


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$ unichars 'NAME =~ /WEARY/'
(nothing)

 

You meant:


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$ unichars -a 'NAME =~ /WEARY/'
😩 U+1F629 WEARY FACE
🙀 U+1F640 WEARY CAT FACE

 

Also, the sophistication of unichars comes at a price: speed. Searching for that weary cat face with uni takes about 0.144s on my laptop. Searching with unichars, 14.899.

When you're just trying to make a stupid joke on Twitter, those 14 seconds aren't worth spending. On the other hand, when you need to actually search for characters matching certain criteria, unichars can do it, and uni can't.

Two More Tools

Unicode::Tussle comes with a bunch more tools, but I'll just show you two more, briefly. uninames is a bit more like uni in that its primary job is to search character descriptions, but its searches aren't limited to character names. It looks at the whole description. For example:


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$ uninames face
 ∯ 222F SURFACE INTEGRAL
  # 222E 222E
 ⌓ 2313 SEGMENT
  = position of a surface
 ⌚ 231A WATCH
  x (alarm clock - 23F0)
  x (clock face one oclock - 1F550)
 ⏰ 23F0 ALARM CLOCK
  x (watch - 231A)
  x (clock face one oclock - 1F550)
...
 ☺ 263A WHITE SMILING FACE
  = have a nice day!

 

We get SURFACE INTEGRAL because it matches /face/i, but why do we get SEGMENT or WATCH? It's because they're related to character with "face" in their descriptions. Sometimes, you'll get a match against a comment about the characters' usage:


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$ uninames fraktur
 ſ 017F LATIN SMALL LETTER LONG S
   * in common use in Roman types until the 18th century
   * in current use in Fraktur and Gaelic types
...

 

Finally, there's uniprops. This is a wonderfully useful tool, in very limited circumstances. Most often, for me, it comes up when I've got some weird input. Say some user's name isn't working with some data validator. The guy who wrote that validator required names to be (for some insane reason) Latin letters that were either uppercase or lowercase. Our other input validator only has the first half of that constraint: Latin letters. What's happening? Well, the user causing us problems is going by the name “ᴿᴶᴮˢ” – what can uniprops tell us about those?


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~$ uniprops <1d3f>
U+1D3F ‹ᴿ› \N{MODIFIER LETTER CAPITAL R}
    \w \pL \p{L_} \p{Lm}
    All Any Alnum Alpha Alphabetic Assigned InPhoneticExtensions Case_Ignorable
       CI Cased Changes_When_NFKC_Casefolded CWKCF Dia Diacritic L Lm Gr_Base
       Grapheme_Base Graph GrBase ID_Continue IDC ID_Start IDS Letter L_ Latin
       Latn Modifier_Letter Lower Lowercase Phonetic_Extensions Print Word
       XID_Continue XIDC XID_Start XIDS X_POSIX_Alnum X_POSIX_Alpha
       X_POSIX_Graph X_POSIX_Lower X_POSIX_Print X_POSIX_Word

 

So, it's Latin, a Letter, and Lowercase, but not a Lowercase_Letter. What?? Surely this is an anomaly..? We can find out with unichars!


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$ unichars '\p{Letter}' '\P{Lowercase_Letter}' '\P{Uppercase_Letter}' '\p{Latin}'
(131 characters listed)

 

What's the lesson here? You and the other guy should learn what those categories mean. Once you've started doing that, you'll be well on your way down the rabbit hole, and you'll start to find all new uses for these tools… but none is likely to be as much fun as making stupid Tweets.

See Also

Gravatar Image This article contributed by: Ricardo Signes <rjbs@cpan.org>