ruby 101

Ruby 101

Your favoritelanguage

sucks.

Ruby is the greatest

language ever made.

Ruby is the greatest

language ever made.

And if you disagree, you’re wrong.

February 24, 1993

Yukihiro “Matz” Matsumotoまつもとゆきひろ

“I wanted a scripting language that was more powerful than Perl, and more object-oriented than Python. That's why I decided to design my own language.”

“I hope to see Ruby help every programmer in the world to be productive, to enjoy programming, and to be happy.

“That is the primary purpose of the Ruby language.”

“Often people, especially computer engineers, focus on the machines. They think, ‘By doing this, the machine will run faster. By doing this, the machine will run more effectively. By doing this, the machine will something something something.’ They are focusing on machines. But, in fact, we need to focus on humans.”

for (var i=0; i<3; i++) { alert('Hello, world!');}

for (var i=0; i<3; i++) { alert('Hello, world!');}

3.times do puts 'Hello, world!'end

var people = ['Rob','Eugene','Crystal'];for (var i=0; i<people.length; i++) { alert(people[i] + ' loves Ruby');}

var people = ['Rob','Eugene','Crystal'];for (var i=0; i<people.length; i++) { alert(people[i] + ' loves Ruby');}

['Rob','Eugene','Crystal'].each do |name| puts "#{name} loves Ruby"end

var today = new Date();today.setDate(today.getDate() + 2);

var today = new Date();today.setDate(today.getDate() + 2);

2.days.from_now

“Sometimes people jot down pseudo-code on paper. If that pseudo-code runs directly on their computers, it’s best, isn’t it?

“Ruby tries to be like that, like pseudo-code that runs.”

REPL

Read - Eval - Print - Loop

REPL


irb

REPL


irbinteractive ruby

rob$ irb

rob$ irbruby-1.9.2 :001 >

rob$ irbruby-1.9.2 :001 > people = ['Rob','Eugene','Crystal']


=> ["Rob", "Eugene", "Crystal"] ruby-1.9.2 :002 >



people.length



people.length => 3 ruby-1.9.2 :003 >



people.length => 3 ruby-1.9.2 :003 > people.last



people.length => 3 ruby-1.9.2 :003 > people.last => "Crystal"

ruby-1.9.2 :004 >




ruby-1.9.2 :004 > people.reverse




ruby-1.9.2 :004 > people.reverse => ["Crystal", "Eugene",

"Rob"]

ruby-1.9.2 :005 >

The Basics

count = 42

count = 42

amount = 23.83

count = 42

amount = 23.83

language = 'Ruby'

count = 42

amount = 23.83

language = 'Ruby'

text = "#{language} is the best!"

count = 42

amount = 23.83

language = 'Ruby'


people = ['Rob','Eugene','Crystal']

count = 42

amount = 23.83

language = 'Ruby'



person = { :name => 'Rob', :gender => 'male' }

count = 42

amount = 23.83

language = 'Ruby'




this = true

count = 42

amount = 23.83

language = 'Ruby'




this = true

that = false

count = 42

amount = 23.83

language = 'Ruby'




this = true

that = false

nothing = nil


Iterators


Iterators

each find collect each_with_index reject

inject

$('li').each(function(index) { alert('index='+index);});

$('li').each(function(index) { alert('index='+index);});

an_array.each do |item| puts "item=#{item}"end

Loops?

Conditionals

if person.has_red_hair? Sun.burn personend


unless car.sugar_in_gas_tank? car.startend



15.times { wash_hands } if person.ocd?



15.times { wash_hands } if person.ocd?

car.accelerate unless TrafficLight.is_red?

if just_worked_out and date_tonight take_a_showerend


if love_mom or just_drunk get_a_tattooend


if love_mom or just_drunk get_a_tattooend

if taco_bell? and not pepto_bismol_nearby? get_to_bathroom!end

airlines = ['Southwest','United','Delta']

airlines = ['Southwest','United','Delta']airlines.reverse => ['Delta','United','Southwest']

airlines = ['Southwest','United','Delta']airlines.reverse => ['Delta','United','Southwest']puts airlines => ['Southwest','United','Delta']

airlines = ['Southwest','United','Delta']airlines.reverse => ['Delta','United','Southwest']puts airlines => ['Southwest','United','Delta']airlines.reverse! => ['Delta','United','Southwest']

airlines = ['Southwest','United','Delta']airlines.reverse => ['Delta','United','Southwest']puts airlines => ['Southwest','United','Delta']airlines.reverse! => ['Delta','United','Southwest']puts airlines => ['Delta','United','Southwest']

everything is an object

‘Rob’.class

‘Rob’.class => String


42.class


42.class => Fixnum


42.class => Fixnum

(23.45).class


42.class => Fixnum

(23.45).class => Float


42.class => Fixnum


true.class


42.class => Fixnum


true.class => TrueClass


42.class => Fixnum



nil.class


42.class => Fixnum



nil.class => NilClass


42.class => Fixnum




String.class


42.class => Fixnum




String.class => Class


42.class => Fixnum





Class.class


42.class => Fixnum





Class.class => Class


42.class => Fixnum






Class.superclass


42.class => Fixnum






Class.superclass => Module


42.class => Fixnum







Module.superclass


42.class => Fixnum







Module.superclass => Object


42.class => Fixnum








Object.superclass


42.class => Fixnum








Object.superclass => BasicObject


42.class => Fixnum









BasicObject.superclass


42.class => Fixnum









BasicObject.superclass => nil

Class, Object, Module and all other classes are instances of a class Class.Class, Module and Object have a circular dependency as they are in the core of the OO model

Introspection

42.methods

42.methods

[:!, :!=, :!~, :%, :&, :*, :**, :+, :+@, :-, :-@, :/, :<, :<<, :<=, :<=>, :==, :===, :=~, :>, :>=, :>>, :

[], :^, :__id__, :__send__, :abs, :abs2, :angle, :arg, :between?, :ceil, :chr, :class, :clone, :coerce, :conj, :

conjugate, :define_singleton_method, :denominator, :display, :div, :divmod, :downto, :dup, :enum_for,

:eql?, :equal?, :even?, :extend, :fdiv, :floor, :freeze, :frozen?, :gcd, :gcdlcm, :hash, :i, :imag, :imaginar

y, :initialize_clone, :initialize_dup, :inspect, :instance_eval, :instance_exec, :instance_of?, :instance_va

riable_defined?, :instance_variable_get, :instance_variable_set, :instance_variables, :integer?, :is_a?, :

kind_of?, :lcm, :magnitude, :method, :methods, :modulo, :next, :nil?, :nonzero?, :numerator, :object_i

d, :odd?, :ord, :phase, :polar, :pred, :private_methods, :protected_methods, :public_method, :public_

methods, :public_send, :quo, :rationalize, :real, :real?, :rect, :rectangular, :remainder, :respond_to?, :r

espond_to_missing?, :round, :send, :singleton_class, :singleton_method_added, :singleton_methods, :

size, :step, :succ, :taint, :tainted?, :tap, :times, :to_c, :to_enum, :to_f, :to_i, :to_int, :to_r, :to_s, :trunca

te, :trust, :untaint, :untrust, :untrusted?, :upto, :zero?, :|, :~]

var method = 'first_name'eval('person.' + method)

var method = 'first_name'eval('person.' + method)

method = 'first_name'person.send(method)

2 + 2

2.+(2)

2 + 2

2.+(2)

2.send('+',2)

Syntactic Sugar

2 == 2

2 == 2

2.==(2)

2 == 2

2.==(2)

2.send('==',2)

Ruby removes the cruft

car = Vehicle.new('honda', 'civic', { :interior => 'beige' })

car = Vehicle.new 'honda', 'civic', :interior => 'beige'

Beautiful code

class Person attr_accessor 'gender','eyes','chin','name' def initialize(gender,eyes,chin) @gender = gender @eyes = eyes @chin = chin endend


rob = Person.new 'male','blue','square'


rob = Person.new 'male','blue','square'aimee = Person.new 'female','brown','cleft'

class Person def +(other_person) gene_pool = [self,other_person] Person.new selection(gene_pool,'gender'), selection(gene_pool,'eyes'), selection(gene_pool,'chin') end def selection(gene_pool,feature) return gene_pool[rand(gene_pool.size)].send feature end private 'selection'end

baby = rob + aimee

baby = rob + aimeebaby.name = 'Jack'


baby.name=('Jack')


baby.name=('Jack')

baby.inspect


baby.name=('Jack')

baby.inspect

#<Person:0x0000010083fdf0 @gender="male", @eyes="blue", @chin="cleft", @name="Jack">

“When I am working on a problem I never think about beauty. I think only how to solve the problem. But when I have finished, if the solution is not beautiful, I know it is wrong.”

— R. Buckminster Fuller

return gene_pool[rand(gene_pool.size)].send feature


class Array def random return self[rand(self.length)] endend



return gene_pool.random.send feature

unless [].respond_to? 'random' class Array def random return self[rand(self.length)] end endend

MonkeyPatching!!1!one!!!

David Heinemeier Hansson (DHH)“Why Ruby”

http://confreaks.net/system/assets/datas/694/original/431-rubyconf2010-keynote-why-ruby-small.mp4?1291226733




“UNIX was not designed to stop its users from doing stupid things, as that would also stop them from doing clever things.” — Doug Gwyn

“There is not now, nor has there ever been, nor will there ever be, any programming language in which it is the least bit difficult to write bad code.” — Anonymous


class Person attr_accessor 'gender','eyes','chin','name' def initialize(gender,eyes,chin) @gender = gender @eyes = eyes @chin = chin end

def +(other_person) gene_pool = [self,other_person] Person.new selection(gene_pool,'gender'), selection(gene_pool,'eyes'), selection(gene_pool,'chin') end def selection(gene_pool,feature) return gene_pool.random.send feature end private 'selection'end

using System;using System.Collections.Concurrent;using System.Collections.Specialized;using System.ComponentModel.Composition;using System.Diagnostics;using System.IO;using System.IO.Compression;using System.Net;using System.Text.RegularExpressions;using System.Threading;using System.Linq;using Newtonsoft.Json;using NLog;using Raven.Abstractions.Data;using Raven.Abstractions.Exceptions;using Raven.Abstractions.MEF;using Raven.Http.Abstractions;using Raven.Http.Exceptions;using Raven.Http.Extensions;using Formatting = Newtonsoft.Json.Formatting;namespace Raven.Http{ public abstract class HttpServer : IDisposable { private const int MaxConcurrentRequests = 192; protected readonly IResourceStore DefaultResourceStore; protected readonly IRavenHttpConfiguration DefaultConfiguration; private readonly ThreadLocal<string> currentTenantId = new ThreadLocal<string>(); private readonly ThreadLocal<IResourceStore> currentDatabase = new ThreadLocal<IResourceStore>(); private readonly ThreadLocal<IRavenHttpConfiguration> currentConfiguration = new ThreadLocal<IRavenHttpConfiguration>(); protected readonly ConcurrentDictionary<string, IResourceStore> ResourcesStoresCache = new ConcurrentDictionary<string, IResourceStore>(StringComparer.InvariantCultureIgnoreCase); private readonly ConcurrentDictionary<string, DateTime> databaseLastRecentlyUsed = new ConcurrentDictionary<string, DateTime>();

public int NumberOfRequests { get { return Thread.VolatileRead(ref physicalRequestsCount); } } [ImportMany] public OrderedPartCollection<AbstractRequestResponder> RequestResponders { get; set; } public IRavenHttpConfiguration Configuration { get { return DefaultConfiguration; } } public abstract Regex TenantsQuery { get; } private HttpListener listener; private static readonly Logger logger = LogManager.GetCurrentClassLogger(); private int reqNum; // concurrent requests // we set 1/4 aside for handling background tasks private readonly SemaphoreSlim concurretRequestSemaphore = new SemaphoreSlim(MaxConcurrentRequests); private Timer databasesCleanupTimer; private int physicalRequestsCount; public bool HasPendingRequests

{ get { return concurretRequestSemaphore.CurrentCount != MaxConcurrentRequests; } }protected HttpServer(IRavenHttpConfiguration configuration, IResourceStore resourceStore) {

DefaultResourceStore = resourceStore; DefaultConfiguration = configuration; configuration.Container.SatisfyImportsOnce(this); foreach (var requestResponder in RequestResponders) { requestResponder.Value.Initialize(() => currentDatabase.Value, () => currentConfiguration.Value, () => currentTenantId.Value, this); } } #region IDisposable Members public void Dispose() { databasesCleanupTimer.Dispose(); if (listener != null && listener.IsListening) listener.Stop(); foreach (var documentDatabase in ResourcesStoresCache) { documentDatabase.Value.Dispose(); } } #endregion public void Start() { listener = new HttpListener(); string virtualDirectory = DefaultConfiguration.VirtualDirectory; if (virtualDirectory.EndsWith("/") == false) virtualDirectory = virtualDirectory + "/"; listener.Prefixes.Add("http://" + (DefaultConfiguration.HostName ?? "+") + ":" + DefaultConfiguration.Port + virtualDirectory);

switch (DefaultConfiguration.AnonymousUserAccessMode) { case AnonymousUserAccessMode.None: listener.AuthenticationSchemes = AuthenticationSchemes.IntegratedWindowsAuthentication; break; case AnonymousUserAccessMode.All: listener.AuthenticationSchemes = AuthenticationSchemes.IntegratedWindowsAuthentication | AuthenticationSchemes.Anonymous; listener.AuthenticationSchemeSelectorDelegate = request => {if(request.RawUrl.StartsWith("/admin",StringComparison.InvariantCultureIgnoreCase))

return AuthenticationSchemes.IntegratedWindowsAuthentication; return AuthenticationSchemes.Anonymous; }; break; case AnonymousUserAccessMode.Get: listener.AuthenticationSchemes = AuthenticationSchemes.IntegratedWindowsAuthentication | AuthenticationSchemes.Anonymous; listener.AuthenticationSchemeSelectorDelegate = request => { return IsGetRequest(request.HttpMethod, request.Url.AbsolutePath) ? AuthenticationSchemes.Anonymous | AuthenticationSchemes.IntegratedWindowsAuthentication : AuthenticationSchemes.IntegratedWindowsAuthentication; }; break; default: throw new ArgumentException("Cannot understand access mode: " + DefaultConfiguration.AnonymousUserAccessMode); } databasesCleanupTimer = new Timer(CleanupDatabases, null, TimeSpan.FromMinutes(1), TimeSpan.FromMinutes(1)); listener.Start(); listener.BeginGetContext(GetContext, null); }

private void CleanupDatabases(object state) { var databasesToCleanup = databaseLastRecentlyUsed .Where(x=>(DateTime.Now - x.Value).TotalMinutes > 10) .Select(x=>x.Key) .ToArray(); foreach (var db in databasesToCleanup) { DateTime _; databaseLastRecentlyUsed.TryRemove(db, out _); IResourceStore database; if(ResourcesStoresCache.TryRemove(db, out database)) database.Dispose(); } } private void GetContext(IAsyncResult ar) { IHttpContext ctx; try { ctx = new HttpListenerContextAdpater(listener.EndGetContext(ar), DefaultConfiguration); //setup waiting for the next request listener.BeginGetContext(GetContext, null); } catch (InvalidOperationException) { // can't get current request / end new one, probably // listner shutdown return; } catch (HttpListenerException) { // can't get current request / end new one, probably // listner shutdown return; }

if (concurretRequestSemaphore.Wait(TimeSpan.FromSeconds(5)) == false) { HandleTooBusyError(ctx); return; } try { Interlocked.Increment(ref physicalRequestsCount); HandleActualRequest(ctx); } finally

{ concurretRequestSemaphore.Release(); } } public void HandleActualRequest(IHttpContext ctx) { var sw = Stopwatch.StartNew(); bool ravenUiRequest = false; try { ravenUiRequest = DispatchRequest(ctx); } catch (Exception e) { HandleException(ctx, e); if (ShouldLogException(e))logger.WarnException("Error on request", e); } finally { try { FinalizeRequestProcessing(ctx, sw, ravenUiRequest); } catch (Exception e) { logger.ErrorException("Could not finalize request properly", e); }

protected virtual bool ShouldLogException(Exception exception) { return true; } private void FinalizeRequestProcessing(IHttpContext ctx, Stopwatch sw, bool ravenUiRequest)

{ LogHttpRequestStatsParams logHttpRequestStatsParam = null; try{ logHttpRequestStatsParam = new LogHttpRequestStatsParams(

sw, ctx.Request.Headers, ctx.Request.HttpMethod, ctx.Response.StatusCode,

ctx.Request.Url.PathAndQuery); } catch (Exception e){ logger.WarnException("Could not gather information to log request stats",

e); } ctx.FinalizeResonse(); sw.Stop(); if (ravenUiRequest || logHttpRequestStatsParam == null) return;LogHttpRequestStats(logHttpRequestStatsParam); ctx.OutputSavedLogItems(logger); }private void LogHttpRequestStats(LogHttpRequestStatsParams logHttpRequestStatsParams) { // we filter out requests for the UI because they fill the log with information // we probably don't care about them anyway. That said, we do output them if they take too // long.

if (logHttpRequestStatsParams.Headers["Raven-Timer-Request"] == "true" && logHttpRequestStatsParams.Stopwatch.ElapsedMilliseconds <= 25) return; var curReq = Interlocked.Increment(ref reqNum); logger.Debug("Request #{0,4:#,0}: {1,-7} - {2,5:#,0} ms - {5,-10} - {3} - {4}",

curReq, logHttpRequestStatsParams.HttpMethod, logHttpRequestStatsParams.Stopwatch.ElapsedMilliseconds, logHttpRequestStatsParams.ResponseStatusCode, logHttpRequestStatsParams.RequestUri, currentTenantId.Value); } private void HandleException(IHttpContext ctx, Exception e) { try { if (e is BadRequestException) HandleBadRequest(ctx, (BadRequestException)e); else if (e is ConcurrencyException) HandleConcurrencyException(ctx, (ConcurrencyException)e); else if (TryHandleException(ctx, e)) return; else HandleGenericException(ctx, e); } catch (Exception) { logger.ErrorException("Failed to properly handle error, further error handling is ignored", e); } } protected abstract bool TryHandleException(IHttpContext ctx, Exception exception);

private static void HandleTooBusyError(IHttpContext ctx) { ctx.Response.StatusCode = 503; ctx.Response.StatusDescription = "Service Unavailable"; SerializeError(ctx, new { Url = ctx.Request.RawUrl, Error = "The server is too busy, could not acquire transactional access" }); } private static void HandleGenericException(IHttpContext ctx, Exception e) { ctx.Response.StatusCode = 500; ctx.Response.StatusDescription = "Internal Server Error"; SerializeError(ctx, new { Url = ctx.Request.RawUrl, Error = e.ToString() }); } private static void HandleBadRequest(IHttpContext ctx, BadRequestException e) { ctx.SetStatusToBadRequest(); SerializeError(ctx, new { Url = ctx.Request.RawUrl, e.Message, Error = e.Message }); }

private static void HandleConcurrencyException(IHttpContext ctx, ConcurrencyException e) { ctx.Response.StatusCode = 409; ctx.Response.StatusDescription = "Conflict"; SerializeError(ctx, new { Url = ctx.Request.RawUrl, e.ActualETag, e.ExpectedETag, Error = e.Message }); } protected static void SerializeError(IHttpContext ctx, object error) { var sw = new StreamWriter(ctx.Response.OutputStream); new JsonSerializer().Serialize(new JsonTextWriter(sw) { Formatting = Formatting.Indented, }, error); sw.Flush(); } private bool DispatchRequest(IHttpContext ctx) { if (AssertSecurityRights(ctx) == false) return false; SetupRequestToProperDatabase(ctx); CurrentOperationContext.Headers.Value = ctx.Request.Headers; try { OnDispatchingRequest(ctx); if (DefaultConfiguration.HttpCompression) AddHttpCompressionIfClientCanAcceptIt(ctx);

AddAccessControlAllowOriginHeader(ctx); foreach (var requestResponderLazy in RequestResponders) { var requestResponder = requestResponderLazy.Value; if (requestResponder.WillRespond(ctx)) { requestResponder.Respond(ctx); return requestResponder.IsUserInterfaceRequest; } } ctx.SetStatusToBadRequest(); if (ctx.Request.HttpMethod == "HEAD") return false; ctx.Write( @"<html> <body> <h1>Could not figure out what to do</h1> <p>Your request didn't match anything that Raven knows to do, sorry...</p> </body></html>"); } finally { CurrentOperationContext.Headers.Value = new NameValueCollection(); currentDatabase.Value = DefaultResourceStore; currentConfiguration.Value = DefaultConfiguration; } return false; } protected virtual void OnDispatchingRequest(IHttpContext ctx){}

private void SetupRequestToProperDatabase(IHttpContext ctx) { var requestUrl = ctx.GetRequestUrlForTenantSelection(); var match = TenantsQuery.Match(requestUrl); if (match.Success == false) { currentTenantId.Value = Constants.DefaultDatabase; currentDatabase.Value = DefaultResourceStore; currentConfiguration.Value = DefaultConfiguration; } else { var tenantId = match.Groups[1].Value; IResourceStore resourceStore; if(TryGetOrCreateResourceStore(tenantId, out resourceStore)) { databaseLastRecentlyUsed.AddOrUpdate(tenantId, DateTime.Now, (s, time) => DateTime.Now);

if (string.IsNullOrEmpty(Configuration.VirtualDirectory) == false && Configuration.VirtualDirectory != "/"){ ctx.AdjustUrl(Configuration.VirtualDirectory +

match.Value); } else {ctx.AdjustUrl(match.Value); }

currentTenantId.Value = tenantId; currentDatabase.Value = resourceStore; currentConfiguration.Value = resourceStore.Configuration; } else { throw new BadRequestException("Could not find a database named: " + tenantId); } } }

protected abstract bool TryGetOrCreateResourceStore(string name, out IResourceStore database); private void AddAccessControlAllowOriginHeader(IHttpContext ctx) { if (string.IsNullOrEmpty(DefaultConfiguration.AccessControlAllowOrigin)) return; ctx.Response.AddHeader("Access-Control-Allow-Origin", DefaultConfiguration.AccessControlAllowOrigin); } private static void AddHttpCompressionIfClientCanAcceptIt(IHttpContext ctx) { var acceptEncoding = ctx.Request.Headers["Accept-Encoding"]; if (string.IsNullOrEmpty(acceptEncoding)) return; // gzip must be first, because chrome has an issue accepting deflate data // when sending it json text if ((acceptEncoding.IndexOf("gzip", StringComparison.InvariantCultureIgnoreCase) != -1)) { ctx.SetResponseFilter(s => new GZipStream(s, CompressionMode.Compress, true)); ctx.Response.AddHeader("Content-Encoding","gzip"); } else if (acceptEncoding.IndexOf("deflate", StringComparison.InvariantCultureIgnoreCase) != -1) { ctx.SetResponseFilter(s => new DeflateStream(s, CompressionMode.Compress, true)); ctx.Response.AddHeader("Content-Encoding", "deflate"); } } private bool AssertSecurityRights(IHttpContext ctx) { if (DefaultConfiguration.AnonymousUserAccessMode == AnonymousUserAccessMode.None && IsInvalidUser(ctx)) {ctx.SetStatusToUnauthorized(); return false; }

IHttpRequest httpRequest = ctx.Request; if (DefaultConfiguration.AnonymousUserAccessMode == AnonymousUserAccessMode.Get && IsInvalidUser(ctx) && IsGetRequest(httpRequest.HttpMethod, httpRequest.Url.AbsolutePath) == false ) { ctx.SetStatusToUnauthorized(); return false; } return true; } protected virtual bool IsGetRequest(string httpMethod, string requestPath) {

return (httpMethod == "GET" || httpMethod == "HEAD"); } private static bool IsInvalidUser(IHttpContext ctx) { return (ctx.User == null || ctx.User.Identity == null || ctx.User.Identity.IsAuthenticated == false); } public void ResetNumberOfRequests() {

Interlocked.Exchange(ref reqNum, 0); Interlocked.Exchange(ref physicalRequestsCount, 0); } }}

517 lines of code

webserver = TCPServer.new('127.0.0.1', 3000)while (session = webserver.accept) session.print "HTTP/1.1 200/OK\r\nContent-type:text/html\r\n\r\n" request = session.gets filename = request.match(/\/(.*?) /)[1] filename = 'index.html' if filename == '' begin session.print File.read(filename) rescue Errno::ENOENT session.print 'File not found' end session.closeend

“There are two ways of constructing a software design: One way is to make it so simple that there are obviously no deficiencies and the other way is to make it so complicated that there are no obvious deficiencies.” — C.A.R. Hoare

class Person def +(other_person) gene_pool = [self,other_person] Person.new selection(gene_pool,'gender'), selection(gene_pool,'eyes'), selection(gene_pool,'chin') end def selection(gene_pool,feature) return gene_pool[rand(gene_pool.size)].send feature end private 'selection'end

Implicit return

Any statement in Ruby returns the value of the

last evaluated expression

ruby-1.9.2 :001 > puts 'Hello, world!'

ruby-1.9.2 :001 > puts 'Hello, world!'Hello, world! => nil ruby-1.9.2 :002 >

ruby-1.9.2 :001 > puts 'Hello, world!'Hello, world! => nil ruby-1.9.2 :002 > puts('Hello, world!')

ruby-1.9.2 :001 > puts 'Hello, world!'Hello, world! => nil ruby-1.9.2 :002 > puts('Hello, world!')Hello, world! => nil ruby-1.9.2 :003 >

Blabber

Talk to your servers via IM

rob$ gem install rails

rob$ gem install railsrob$ gem install httparty json

require 'rubygems'require 'json'require 'httparty'

rob$ irbruby-1.9.2 :001 >

rob$ irbruby-1.9.2 :001 > HTTParty

rob$ irbruby-1.9.2 :001 > HTTPartyNameError: uninitialized constant Object::HTTParty from (irb):1 from /Users/rob/.rvm/rubies/ruby-1.9.2-p180/bin/irb:16:in `<main>'ruby-1.9.2 :002 >

rob$ irbruby-1.9.2 :001 > HTTPartyNameError: uninitialized constant Object::HTTParty from (irb):1 from /Users/rob/.rvm/rubies/ruby-1.9.2-p180/bin/irb:16:in `<main>'ruby-1.9.2 :002 > require 'httparty'

rob$ irbruby-1.9.2 :001 > HTTPartyNameError: uninitialized constant Object::HTTParty from (irb):1 from /Users/rob/.rvm/rubies/ruby-1.9.2-p180/bin/irb:16:in `<main>'ruby-1.9.2 :002 > require 'httparty' => true ruby-1.9.2 :003 >

rob$ irbruby-1.9.2 :001 > HTTPartyNameError: uninitialized constant Object::HTTParty from (irb):1 from /Users/rob/.rvm/rubies/ruby-1.9.2-p180/bin/irb:16:in `<main>'ruby-1.9.2 :002 > require 'httparty' => true ruby-1.9.2 :003 > HTTParty

rob$ irbruby-1.9.2 :001 > HTTPartyNameError: uninitialized constant Object::HTTParty from (irb):1 from /Users/rob/.rvm/rubies/ruby-1.9.2-p180/bin/irb:16:in `<main>'ruby-1.9.2 :002 > require 'httparty' => true ruby-1.9.2 :003 > HTTParty => HTTParty ruby-1.9.2 :004 >

Questions?

Workshop

Command line interface to the Active.com Search

API

It should:

It should:

• Present a list of channels and let the user select one

It should:


• Prompt for (optional) keywords

It should:


• Prompt for (optional) keywords• Present the top 10 results

It should:


• Prompt for (optional) keywords• Present the top 10 results• Let the user select one result

It should:


• Prompt for (optional) keywords• Present the top 10 results• Let the user select one result • Present the title, location, start

date and asset ID of the selected event

Example

What you need to know

Required Gems

require 'json'require 'httparty'

Search API Endpoint

http://api.amp.active.com/search? v=json& k=keywords& m=meta:channel%3DRunning& api_key=wuhmn9ye94xn3xnteudxsavw

http://api.amp.active.com/search?f=activities&v=json&l=92121&r=10&s=relevance&api_key=wuhmn9ye94xn3xnteudxsavw&num=10








HTTP call

HTTParty.get(url)


Parse JSON

JSON.parse(text)

HTTP call

HTTParty.get(url)



Get user inputuser_input = gets


Remove newlinesuser_input.chomp


Print to STDOUTprint 'text'puts 'text'

Remove newlinesuser_input.chomp

Iterate through array with index

my_array.each_with_index do |item,i| puts “#{item} is at position #{i}”end

Exitexit 0

Iterate through array with index

my_array.each_with_index do |item,i| puts “#{item} is at position #{i}”end

Define methodsdef method_name(first, second) # codeend

Create classes

class ClassName def initialize # code endend

Questions?

require 'json'require 'httparty'

HTTParty.get(url)

JSON.parse(text)

user_input = gets

print 'text'puts 'text'

user_input.chomp

my_array.each_with_index do |item,i| puts “#{item} is as position #{i}”end

http://api.amp.active.com/search? v=json& k=keywords& m=meta:channel%3DRunning& api_key=wuhmn9ye94xn3xnteudxsavw

exit 0



http://api.amp.active.com/search?v=json&k=keywords&m=meta:channel%3DRunning&api_key=







“I am rarely happier than when spending an entire day programming my computer to perform automatically a task that would otherwise take me a good ten seconds to do by hand.” — Douglas Adams

Learning a new language

“Would you rather be a king of fools or a

student of masters?”

The End

ruby 101

Technology