Today was my first day at Hacker School.
I learned about decorators from Erik Taubeneck.
Decorators can be seen as a way to wrap arbitrary functions. Decorating the method
foo with the decorator @bar is syntactically equivalent to
foo = bar(foo) — that is, redefining foo to always be passed through bar.
The reason you'd want to do this: you can abstract out a lot of boilerplate that might apply to many different functions. As a bonus that boilerplate doesn't have to be in one spot; it can be at the beginning and end of the functions you want to call. For instance, if you need to run authentication checks on lots of functions in your web app, you can decorate all those functions with an authentication decorator.
Then, when you define the decorator, it takes a function as an argument and returns that function depending on whatever logic you like. So for instance it would take your user operation, check for authentication, and return the operation if the user was authenticated (and the operation would then run normally), and return a redirect function if the user is not authenticated.
During my first week I worked on an application called abba—the abbreviation engine.
abba began life as an adaptation of the New Abbreviations, the shorthand system that I've been working on since 2006. I wanted to write an application that could basically model the the Abbreviations—the challenge being that many of the abbreviations I made up have no unicode equivalents, and so you couldn't simply write a script to do unicode character replacement.
abba does is insert references to abbreviation objects, which exist independently of their representation in any given medium. It does this by the rather clever method—originally suggested by Tom, I think—of passing through single high-plane unicode characters which can then be dereferenced at rendering time.
The original version of the app that I wrote on Tuesday treated strings as lists of chars and simply inserted the abbreviation objects directly into the lists in the place of the character sequence to be replaced. This had the desired effect but the math was laborious, as you ended up after only a single pass with heterogeneous lists, that had to be traversed, broken up into two lists—one for chars and one for objects—which were then worked upon separately, and finally recombined.
On Wednesday, though, I rewrote the program to use single unicode characters to reference abbreviation objects. This radically simplified the logic involved, because the resulting lists were homogeneous lists of chars—mutable strings, in other words—which meant they could be acted on in-place, in a single pass. And regular expressions provide a very powerful framework for doing string substitutions.
For my own sense of propriety and politesse I decided to programmatically assign the unicode control chars from the Private Use Area, which is designated to be unused by official encodings. I originally thought it might be nice to use Plane 15, the supplemental Private Use Area-A, but that would involve the use of double-wide surrogate pair characters and complicate the issue. Later concerns ended up persuading me to move to Python 3 (where everything is a unicode string), which might have mooted the problem, but in any case it seems saner and more extensible to restrict myself to the standard private use area, which still presents me with 6400 codepoints to make use of.
In any case, I should implement something pretty soon that sanitizes the source data before the abbreviations are applied, escaping any characters in that range that are already in the document.
abba the specific abbreviations are abstracted away from the program itself. So, while the New Abbreviations will be the main data set that I write for myself, it's important that any user be able to write whatever set of abbreviations they would like to see.
Right now the abbreviation definitions are stored in a json file that describes a series of sets of regular expression transforms. One exciting feature that I'm working on right now is my own markup language for describing abbreviations to make them easier to write.
Right now each abbreviation is stored as a regular expression that it matches to, its name, and then its realization in a given renderer (unicode is the one I'm starting with), if it has one. But I intend for the user to be able to use a much simpler patterning system if they like, for instance, writing
er.terminal.initial which the system will compile into
"er(?=\\b)|(?=\\b)er", and so on.
Part of this markup system is necessary to be able to refer to other abbreviations within the abbreviation system: a major bug is the fact that ordinarily, the regular expression library doesn't recognize the private use characters as word characters (understandably so), and thus has trouble combining them sensibly.
Finally, I'm building into
abba the ability to actually generate its own abbreviation rules on the fly.
If the user so desires, abba can take any given text, perform some word and letter sequence frequency analysis on it (right now very simple), and produce its own set of abbreviation rules with randomly-assigned abbreviation characters to apply to the text in question. The ruleset is treated exactly the same as a ruleset read from a JSON file, so anything that
abba can do in one mode, it can do in the other. I think this is quite fun.
One happy result of working on
abba is that it's informed my understanding of the Abbreviations, too. One immediate and obvious consequence is that it will force me to very rigorously define positioning rules and such; any place where I've been allowing myself to fudge things a little when composing texts—because things will be immediately obvious from context—will be exposed, and the
abba implementation of the New Abbreviations will evolve as a reference implementation of the Abbreviations themselves.
Something else that this has pointed out to me is that the unicode realization of any given abbreviation and my handwritten realization of that abbreviation need not be very similar at all. Precisely because abbreviations are objects, with multiple renderings, before they are unicode characters, means that I can happily say that 'in', for instance, can look like 'ɹ' in unicode and look like something similar, but distinct, when written by hand. And if I want to write a bitmap outputter or something that replicates the glyphs as they're written by hand at a later date, I can.
The lack of availability of a certain character is not the only good reason to divorce typeset and handwritten realizations, either. There's also just good typesetting practice. For instance, terminal er in the Abbreviations looks more or less like 'ɛ' with one more hook coming off the bottom, if that makes sense. The closest unicode analog is Ę, CAPITAL LETTER E WITH OGONEK. But it quickly became apparent that Ę looks very awkward at the end of a word. It's a capital letter and the eye has very specific expectations for where capital letters are to be found. So I made the unicode version of terminal er into ę, instead. That's a little awkward to unambiguously write by hand, but it makes perfect sense when reading typewritten text. And of course this relationship of very light digraphia is already very much the norm whenever one compares typeset text and handwritten text.
So here's a little sample of what
abba looks like as of right now. It's very much in development but it's already pretty fun to look at. Allow me to run through the first couple posts in my stream about the New Abbreviations:
Foꝛ ð laſt ſix years oꝛ ſo, I'v̯ woꝛk̳ on a complet̯ ⁊ compꝛehenſiv̯ ſyſtem of tranſcription-bas̳ ʃoꝛðaͫ Ⱳc tak̯s its ɹſpiration pꝛimari᷏ from ðeabbꝛeviation̯s of ð medieval ſcribal tradition. It's tailoꝛ̳ pꝛimari᷏ foꝛ wꝛiti̫ ɹ E̫liʃ, ðouȝ it's uſeabl̯ ɹ any la̫uag̯ ðt uſes ð Latin ɖaraɥę ſet. It compꝛiſes about 150 ɹdividual ɖaraɥ੭s, ðouȝ a ſizeabl̯ ɖṵ of ðoſe ɖaraɥ੭s ar̯ diacritics ðt ç combin̯ WITH oðęs ŧ foꝛm a v੭y flexibl̯, denſe, ⁊ a̯sðetical᷏ pleaſi̫ ſyſtem. I'v̯ docum̯̳̃ ðs ſyſtem ɹ a ſliȝt᷏ l̯ſs-ðan-matuꝛe foꝛm; it's closę ŧ featuꝛe complet̯ now. Ev੭y ſo often I conſidę ð b̯ſt way ŧ publiʃ ð ſyſtem foꝛ widę conſumption.
Arguab᷏ ð v੭y firſt ði̫ ðt needs ŧ b̯ don̯ ǂ ŧ freez̯ ð featuꝛe ſet, as it w੭e, ⁊ defin̯ a v੭ſion 1.0 onc̯ I'm confid̯̃ it's got a‖ ð glyphs foꝛ woꝛds ⁊ ɖaraɥę combinations foꝛ a firſt paſs.
ðr ar̯ ſev੭al t̯ɖnical conſid੭ations aftę ðt. ð lett੭s n̯̳ ŧ b̯ wꝛitten by haͫ ⁊ ſcann̳.
But I alſo n̯̳ ŧ eſtabliʃ a way ŧ repꝛeſẽ ðem ɹ pꝛĩ̳ text; cuꝛr̯᷏̃ I hav̯ a larg̯ numbę of bitmaps ðt I mad̯ from editi̫ a fix̳-widð pixel fõ. ðs may oꝛ may not b̯ ð b̯ſt way. Obvious᷏ a fu‖ featuꝛ̳ typefac̯ would b̯ b̯ſt but ðt miȝt b̯ beyoͫ my abiliti̯s.
ſecoͫ ðr's ð qu̯ſtion of how ŧ compoſe ð docum̯̃s; wh̯ðę ŧ put ŧg̯ðę a PDF docum̯̃ oꝛ a navigabl̯ webſit̯.
On̯ of ð qu̯ſtions ŧ anſwę h੭e ǂ, Ⱳt ǂ ð puꝛpoſe of docum̯̃i̫ it ɹ ð firſt plac̯? Oꝛ moꝛe dir̯ɥ᷏—ǂ it exp̯ɥabl̯ ðt anybody who iſn't m̃ would
a) Hav̯ ɹt੭eſt ɹ learni̫ ðs ſyſtem, ⁊ b) B̯ abl̯ ŧ learn it ŧ ð degre̯ ðt I hav̯?
It requir̯s eßẽial᷏ no ðouȝt foꝛ m̃ ŧ wꝛit̯ ɹ ðs ſyſtem. But ðt muſt b̯ ɹ larg̯ part becauſe I cam̯ up WITH it; ⁊ becauſe I cam̯ up WITH ɹdividual ɖaraɥ੭s ovę ð couRSE of tim̯.
I hav̯ no exp੭ienc̯ WITH any ſoꝛt of beta t̯ſt੭s, ɹ oðę woꝛds.
And here's the same text with generator mode enabled:
ȷ Ɨ laӶ six yeϮs Ƒ so, I've worked on a ӄmpȵӼ ϒ ӄmpɮhensive Ԙ ʎ trѼscription-based shorӕѼd which takes ɑs Ϻspirϟion primϮily from ӕeabbɮviϟiones ʎ Ɨ medieval scribal tradɑion. ԡ's tailoɮd primϮily ȷ wrɑϺg ϗ Englƫh, ӕough ԡ's useabȵ ϗ Ѽy lѼguage Ʒ uses Ɨ LϟϺ chϮacӼr set. ԡ ӄmprƫes about 150 Ϻdividual ζ, ӕough a sizeabȵ chunk ʎ ӕose ζ Ϯe diacrɑics Ʒ cѼ ӄmbϺe ϙ oӕϏs ɲ form a vϏy fȵxibȵ, dense, ϒ aesӕetically pȵasϺg Ԙ. I've documenӼd Σ Ԙ ϗ a slightly ȵss-ӕѼ-mϟuɮ form; ԡ's closϏ ɲ feϟuɮ ӄmpȵӼ now. EvϏy so ofӼn I ӄnsidϏ Ɨ Ї ϸ ɲ publƫh Ɨ Ԙ ȷ widϏ ӄnsumption.
Ϯguably Ɨ vϏy Ρ ӕϺg Ʒ needs ɲ ӓ done Ȟ ɲ fɮeze Ɨ feϟuɮ set, as ԡ wϏe, ϒ defϺe a vϏsion 1.0 once I'm ӄnfident ԡ's got all Ɨ glyphs ȷ words ϒ chϮacӼr ӄmbϺϟions ȷ a Ρ pass.
ӕϏe Ϯe sevϏal Ӽchnical ӄnsidϏϟions afӼr Ʒ. Ɨ ȵtӼrs need ɲ ӓ wrɑӼn by hѼd ϒ scѼned.
But I also need ɲ eӶablƫh a ϸ ɲ ɮpɮsent ӕem ϗ prϺӼd Ӽxt; curɮntly I ʉ a lϮge numƢr ʎ bɑmaps Ʒ I made from edɑϺg a fixed-widӕ pixel font. Σ may Ƒ may not ӓ Ɨ Ї ϸ. Obviously a full feϟuɮd typeface would ӓ Ї but Ʒ might ӓ Ƣyond my abilɑies.
Seӄnd ӕϏe's Ɨ queӶion ʎ how ɲ ӄmpose Ɨ documents; wheӕϏ ɲ put ҰgeӕϏ a PDF document Ƒ a navigabȵ websɑe.
One ʎ Ɨ queӶions ɲ ѼswϏ hϏe Ȟ, whϟ Ȟ Ɨ purpose ʎ documentϺg ԡ ϗ Ɨ Ρ place? Ƒ moɮ diɮctly—Ȟ ԡ expectabȵ Ʒ Ѽybody who ƫn't me would
a) ʉ ϺӼɮӶ ϗ ȵϮnϺg Σ Ԙ, ϒ b) ӓ abȵ ɲ ȵϮn ԡ ɲ Ɨ degɮe Ʒ I ʉ?
ԡ ɮquiɮs essentially no ӕought ȷ me ɲ wrɑe ϗ Σ Ԙ. But Ʒ muӶ ӓ ϗ lϮge pϮt Ƣcause I came up ϙ ԡ; ϒ Ƣcause I came up ϙ Ϻdividual ζ ovϏ Ɨ ӄurse ʎ time.
I ʉ no expϏience ϙ Ѽy sort ʎ Ƣta ӼsӼrs, ϗ oӕϏ words.
This morning I built a small toy called posical, which models August Comte's Positivist Calendar in python. It seems to be a sort of spiritual little brother to abba. Next I'll want to make it understand timedeltas so you can do date math. But finally it seems like it would be fun to generalize it into an all-purpose tool for constructing alternate calendars; god knows there are enough of them floating around and it'd be fun to make a general model.
For the majority of this week I've been working on building a toy framework—a flask clone. Before I came to Hacker School I thought I should learn how to use web frameworks; I'm glad I didn't spend too much time on that because it works very well to learn how they work by building one yourself. Of course mine is not very good for actual production—but I am confident that by the end, I'll have a much firmer grasp on how to pick up any framework from the work I've done implementing my own.
All I really had to do to get started was to work through the flask tutorials to learn what it does, and then through this WSGI tutorial to learn how WSGI applications (of which flask is a member) are put together. Then it was off to the races. Now I can handle routes, serve pages, handle GET and POST, run templates with variable replacement and template extension, and interact with a MongoDB database. Next I want to build conditional logic and looping into my template, then I'm going to try to build an ORM for my framework.
Meanwhile posical is coming along well. Implementing timedeltas and comparisons was a snap; I just downcast them into datetime dates, do the math there, and then make a new posical date with the result.