Learning to Live with the Static Typing Fascist and the Dynamic Typing Fanboy in your Enterprise...

1
Learning to Live with the Static Typing Fascist
and the Dynamic Typing Fanboy in your
Enterprise...

• ARC310

• James Crisp and Jim Webber, ThoughtWorks

2
Roadmap

• Platform
• Code affordances
• Tool support
• Extensibility
• Development Process
• Data access
• Metaprogramming
• Application development
• Integration

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Platform

• Windows!
• .Net 3.5
• Maybe Linux, via Mono

4
Platform

• Anywhere
• Windows
• Linux
• Mac
• CLR
• JVM

5
Readability

• How concise and readable is thecode?
• How much code will I have to maintain?
• How productive can I be?

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Attributes

• class Person
• attr id
• attr_accessor name, age
• end

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Named Parameters

• p Person.new(
• first_name gt "Freddy",
• last_name gt "Flintoff")
• p.update(age gt 72, sexgt'm')

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Default PropertyImplementation

• class Person
• public string FirstName
• get set
• ...

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Initialisers

• Person p new Person
• LastName "Dundee",
• FirstName "Mick"

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Meta Plumbing

• class DomainObject
• def initialize(attributes )
• attributes.each do name, value
• eval("_at_name value")
• end
• end
• end

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Duck Typing

• h House.new( number gt 20 )
• p Phone.new( number gt 123456 )
• p h
• p.number
• gtgt 20

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Type Inference

• var p new Person
• LastName "Smith"

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Who needs Duck Typing?

• interface INumbered
• int Number get
• class House INumbered ...
• class Phone INumbered ...
• INumbered phone
• INumbered house new House()
• phone house
• phone.Number

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Data

• LINQ and Entity Framework
• Castle project
• Active record for .Net
• Builds on NHibernate
• NHibernate too!

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Design Time
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Generate and Use theDatabase

• PersonDataContext pdc new
  PersonDataContext()
• pdc.CreateDatabase()
• var adults from p in pdc.Persons
  where p.Age gt 18 select p
• foreach (Person adult in adults)
• Console.WriteLine(adult.FirstName " "
• adult.LastName)

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Data

• Active Record ships with Rails
• Good for green field web apps
• Objects and properties mapped 11 to tables and
  columns
• Simple API for searching and saving
• Can use underlying platform eg, Hibernate or
  NHibernate

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Lambda Functions

• What are Lambda functions?
• From the functional programming community
• Who?
• Think anonymous inline methods
• C 2.0 anonymous delegates with nicer syntax

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Pass a function into acollection

• ListltPersongt people new
  ListltPersongt()
• people.Add(new Person FirstName "James",
  LastName "Crisp", Age 8 )
• people.Add(new Person FirstName "Jim",
• LastName "Webber", Age 32 )
• people.ForEach(p gt Console.WriteLine(p.FirstNa
  me " " p.LastName))

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Lambda Functions

• codgers people.find p p.age gt 30
• codgers.each c print c.name

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Metaprogramming DSLs

• Method Missing
• DSLs
• Code generation at run time

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Method Missing

• If a method is not defined, falls through to
  method_missing.
• ActiveRecord (part of Rails) uses this to
  generate properties on domain objects at run
  time.
• Allows DSLs like
• Person.find_by_name_and_age('Jim', 84)

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Code Generation atRun Time

• Create new properties, methods and classes on the
  fly
• Redefine, wrap and rename methods
• Eval() a string, and it will be code

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Code Generating DSL

• class Geek lt ActiveRecordBase
• has_many laptops
• has_one girlfriend
• end
• jim Geek.new(name gt 'Jim' )
• laptop Laptop.new(brandgt 'dell')
• jim.laptops ltlt laptop

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rSpec DSL

• describe Geek do
• before(each) do
• _at_geek Geek.new
• end
• it "should have no laptops initially" do
• _at_geek.laptops.count.should 0
• end
• ....

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Autogen andMetaprogramming

• Can generate useful code from metadata at compile
  time
• E.g. Domain objects from database schemas
• E.g. Service proxies from WSDL
• Etc
• Attributes for metaprogramming
• And the reflection APIs if I have to...

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DSLs

• Some support for fluent interfacesin NUnit etc
• Assert.That(...)
• Assert.IsNotNull(...)
• Can create our own DSLs by using cunning class
  name conventions
• E.g. nBehave for BDD
• Like TDD but focussed on behaviour rather than
  implementation

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nBehave DSL

• override public void Specify()
• Given(new RubyProgrammer()).
• When(new BuildingProperSoftware()).
• Then(new RubyProgrammerShouldBeFired())

Tooling available to turn this code into
development stories for xBehave
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Extensible Type System

• All classes are open and can beextended
• Eg, Rails extends Ruby's number class
• gtgt 5.days.from_now
• gt Sun Aug 05 142812 1000 2007
• Existing methods can be removed, wrapped or
  renamed
• Frameworks often designed around re-usable Mixins
  rather than inheritance

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Adding new methods

• class String
• def url?
• self.starts_with? "http//"
• end
• end
• gtgt "hi".url?
• gt false
• gtgt "http//jamescrisp.org".url?
• gt true

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Extensible Type System

• Weve always had interfaces andabstract classes
  from the underlying .Net framework
• Now we have extension methods too...

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Defining Extension Methods

• namespace JimWebber
• public static class WebUriValidator
• public static bool IsValidUri(this
  string str)
• return str.ToLower().StartsWith("http"
  )

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Using Extension Methods

• using JimWebber
• class Program
• static void Main(string args)
• string s "http//jim.webber.name"
• bool b s.IsValidUri()

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Testing

• Unit Testing
• TDD NUnit
• BDD nBehave
• nMock Interfaces easy, classes slightly trickier

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NUnit

• TestFixture
• public class PersonTest
• SetUp
• public void GivenAPersonExists()
• ..
• TearDown
• public void PersonShouldBeRemoved()
• ..
• Test
• public void PersonShouldBeOlderThanZero()
• ...
• Assert.That(p.Age gt 0)

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nMock Example

• InterfaceToBeMocked aMock
  mocks.NewMockltIPersongt()
• Stub.On(aMock).GetProperty("Age")
  .Will(Return.Value(32))
• Expect.Once.On(aMock)
• .GetProperty("FirstName")
• .Will(Return.Value("Jim"))

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Testing

• TDD
• Unit test framework part of standardlibraries
• BDD
• rSpec, rBehave
• Mocks
• Mocha, rMock, FlexMock, etc

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Unit Test Example

• def test_person_is_called_james do
• assert_equal 'James', _at_person.nameend
• OR after a little bit of meta programming
• test 'person is called James' do assert_equal
  'James', _at_person.nameend

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Mocha Example

• p mock('person')
• p.stubs(age).returns(26)
• p.expects(name).returns('James')

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Tool Support

• Visual Studio
• Intellisense, debugger, PowerShell, etc
• Continuous Integration
• CruiseControl.Net and friends
• Build Process
• NAnt, MSBuild, NMaven, etc

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PowerShell

• PS C\Users\Jim Webbergt name "Jim Webber"
• PS C\Users\Jim Webbergt name
• Jim Webber
• PS C\Users\Jim Webbergt name.ToLower()
• jim webber
• PS C\Users\Jim Webbergt
• PS C\Users\Jim Webbergt (xml(new-object
  System.Net.WebClient).DownloadString("http//jim.w
  ebber.name/feeds/atom.aspx")
• ).feed.title
• World Wide Webber

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Tool Support

• IDE
• Visual Studio with Iron Ruby
• IntelliJ, e-Edit, TextMate provide syntax
  highlighting and script support.
• Build Process Rake
• Continuous Integration
• CruiseControl.rb and friends

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Console

• C\rubygtruby script/console
• gtgt p Person.new( name gt 'Jim' )
• gt ltPerson0x49c8d40
• _at_attributes"name"gt"Jim", ...gt
• gtgt p.save
• gtgt name 'Jim'
• gtgt Person.find(first, 'name ', name)
• gt ltPerson0x69c1d40
• _at_attributes"name"gt"Jim", ...gt

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Gems

• C\rubygt gem install mocha
• Bulk updating Gem source index for
  http//gems.rubyforge.org
• Successfully installed mocha-0.5.3
• Installing ri documentation for mocha-0.5.3...
• Installing RDoc documentation for mocha-0.5.3...

45
NMaven
Warning NMaven currently immature

• Apache Incubator project
• Supports repositories for dependencies
• Across the Internet
• Plugs into the standard Maven build cycle
• Will have VS integration
• Extensible through Mono-based plugins
• Also could use Ivy for dependency management...

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Web Apps ? RAILS

• Rails is the most famous and popularRuby
  framework
• Rails provides (among other things)
• Neat MVC framework and route mapping
• Template based views
• Domain focussed business layer
• Active Record and DSLs for persistence
• Easy AJAX and Web 2.0 support
• Auto-generated code (write time and run time)
• Fast change cycle (edit file -gt refresh page)
• Plug-ins for code re-use

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Web Apps

• ASP.Net
• Plus new ASP.Net AJAX functionality
• Combine ASP.Net with Entity Framework for
  Rails-like functionality
• Silverlight
• For richer client functionality

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Rich Client

• Most Ruby dev is Rails and Web 2.0
• There are GTK / Gnome bindings for Ruby and some
  rich client Ruby apps.
• WPF under .NET

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Rich Client

• WPF
• Clear separation of markup andbusiness logic
• Whizzy acceleration and goodness from DirectX 10
• Also the older WinForms stuff is available

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Integration

• WCF
• WS-
• SOAP, WSDL, WS-Sec, WS-SecPol, WS-Trust,
  WS-Federation, WS-Coordination.
  WS-AtomicTransaction, WS-KitchenSink...
• REST Support
• URI templates, WebGet, etc
• Enterprise-y stuff too
• Queues

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Integration

• REST-centric
• Web services are produced like web pages, using
  same framework and routing
• Message Queues using Reliable-Msg or underlying
  JMS or MSMQ
• WS- support
• SOAP4R
• Use underlying platform for WS-, eg, WCF or Java
  frameworks like XFire

52
XML and Friends

• .Net has XmlSerializer (and friends)
• Dom, XPath, templates, etc
• VB has XML literal support...
• Dim x As XElement ltdategt
  ltyeargt2006lt/yeargt ltmonthgt01lt/monthgt
  ltdaygt01lt/daygt lt/dategt

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C Not Tightly Coupled toXML

• var x new XElement("Date")
• x.Add(new XElement("Year", "2006"))
• x.Add(new XElement("Month", "01"))
• x.Add(new XElement("Day", "01"))

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XML and Friends

• XPath and Document Object Modelwell supported
• To generate complex XML (eg, LIXI), the best way
  is templating using Erb
• All objects have to_xml method with serialises
  properties to xml
• XML Builder is nice to work with and leverages
  Ruby's flexible method_missing

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XML Builder

• gtgt builder.date
• ?gt builder.year "2006"
• gtgt builder.month "01"
• gtgt builder.day "01"
• gtgt
• ltdategt
• ltyeargt2006lt/yeargt
• ltmonthgt01lt/monthgt
• ltdaygt01lt/daygt
• ltdategt

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Coexisting in theenterprise

• When to go Ruby versuswhen to use C and .Net?
• Enterprise heavy lifting?
• Cross-language enterprise development?
• And what about mixing C and IronRuby...?

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Questions?

• ARC 310

• Ask James and Jim!

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Evaluation Forms

• ARC 310

• Dont Forget!