Ruby

I’ve started a new side project named Crystal Koans, it’s a simple series of exercises organized as a big unit test suite. The “koans” are heavily inspired by similar projects for other languages, but I didn’t found anything similar for Crystal. The project has been included in the awesome collection under the official Learning Resource for the language. I’ll try to maintain and evolve it in the spare time, I hope you’ll find it useful, and any form of contribution is welcome. ...

I’ve started experimenting with the Crystal Programming Language. It’s a nice and clean language with syntax similar to Ruby, but compiled to fast native code, and a lot of clever ideas, like union types and seamless C integration The project is still in early stages, but it’s promising. Just to see how easy, I ported a small python library to Crystal, you can find it on https://github.com/ilmanzo/spark. I hope to find the time to improve on it! ...

Giocando con Sinatra ho avuto l’esigenza di servire una determinata pagina solo con un certa frequenza (tecnicamente un rate-limit); la cosa si puo’ fare installando il middleware Rack:Throttle ma non volevo aggiungere un’altra gemma alle dipendenze… In questo esempio se al server arriva piu’ di una richiesta in un intervallo di cinque secondi, rispondiamo a tono… SECONDS_BETWEEN_REQUEST=5 enable :sessions def ratelimit? now=Time.new.to_i session['lastrequest']||=0 #inizializza se non presente result=(now-session['lastrequest'])<SECONDS_BETWEEN_REQUEST #passati dall'ultima richiesta ? session['lastrequest']=now # aggiorna return result end get '/' do if ratelimit? return "<h1>sorry, rate limit exceeded!</h1>" end "<h1>hello!</h1>" end

Natale si avvicina: mentre smanettavo su queste ottime PC Engines ALIX su cui ho installato una Debian modificata, ho scritto una comoda interfaccia per accendere/spegnere e far lampeggiare i led alla velocita’ desiderata… class Led #numero da 1 a 3 def initialize(ledno) ledno++ # passo 0 ma comando 1 ledno=1 if ledno<1 ledno=3 if ledno>3 @ledsyspath="/sys/devices/platform/leds_alix2/leds/alix:#{ledno}/" end def blink(millisec) File.open(@ledsyspath+'trigger','w') { |f| f.write('timer') } File.open(@ledsyspath+'delay_off','w') do |f| f.write(millisec.to_s) end File.open(@ledsyspath+'delay_on','w') do |f| f.write(millisec.to_s) end end def blink_slow! blink(500) end def blink_fast! blink(50) end def on! File.open(@ledsyspath+'trigger','w') { |f| f.write('default-on') } File.open(@ledsyspath+'brightness','w') do |f| f.write('1') end end def off! File.open(@ledsyspath+'trigger','w') { |f| f.write("none") } File.open(@ledsyspath+'brightness','w') do |f| f.write('0') end end end