Seaside Portability

Portability in Seaside NYC Smalltalk December 10, 2009

Julian Fitzell Co-creator of Seaside Independent consultant

694 classes

6844 methods

Platforms

External Interface Support XML Support enables XML–Smalltalk object mapping, includes a server interface via XML request handlers and reading of remote resources B disk via TCP sockets using HTTP requests OLE Support enables an application to use OLE clients and custom control services. Domino Connection allows an application to retrieve and work with Domino documents as well as access Notes mail system. Download a risk-free trial copy: www.instantiations.com/VAST/download m/VAST Build Quality Software l other trademarks mentioned are the property of their respective owners.

Portability Photo: Alexia´s, ﬂickr.com

Goals Create consistent experience Minimize platform changes Isolate platform changes Ease code updates (in both directions!)

Namespacing: WAObject #seasideUrl

Syntax Photo: pipp, sxc.hu

n o Underscore Assignments a_1 b←2

n o Brace Arrays { 1. 2. 1 + 2 }

n o Array Constructors #[ ‘string’, 123, Object new ]

n o Byte Arrays #[ 1 2 3 ]

n o Variable Bindings {Smalltalk.Object}

n o Selection Blocks {:i | i.is.permanent}

o k Pragma <javascript: 1.5>

ANSI Photo: njd89, sxc.hu

ANSI Protocols Object, Character, Boolean, nil, etc. Block Exception Numeric Collection Date and Time Stream

Exceptions Photo: ingythewingy, ﬂickr.com

Exception Protocols #signal, #signal:, ... #on:do:, #ensure:, #ifCurtailed: #defaultAction, #isResumable #pass, #outer, #retry, #resume Warning, Error, Notiﬁcation, ZeroDivide, ...

n o [ ... ] on: Error do: [ ... ]

y e s [ ... ] on: Error do: [ |err| ... ]

n o #defaultAction + non-resumable exceptions

“The exact behavior and result of this method is implementation deﬁned.”

Unless the exception is resumable, “the action taken upon completion of the #defaultAction method is implementation deﬁned”

n o MyException signal

Collections Photo: ijsendoorn,sxc.hu

Collection Protocols Array, Set, OrderedCollection, Interval, ... #do:, #collect:, #select:, #reject:, #detect:, ... #includes:, #isEmpty, anySatisfy:, ... #asSet, #asOrderedCollection, ... #at:put:, #at:ifAbsent:, #removeKey:, ...

n o Collection>>#=

n o #withIndexDo:

y e s #keysAndValuesDo:

n o #pairsDo:

y e s 1 to: aCollection size by: 2 do: [ :i | ... ]

Strings Photo: Lynne Lancaster, sxc.hu

n o Symbol is a String

n o #match:

n o Object>>#asString

n o #displayString

n o Non-ASCII Strings

Streams Photo: Lynne Lancaster, sxc.hu

Stream Protocols ReadStream, WriteStream, ReadWriteStream #close, #isEmpty, #position, #reset, ... #do:, #next, #peek, #upTo:, ... #cr, #nextPut:, #nextPutAll:, ...

n o #next, at the end of a stream

y e s Check #atEnd ﬁrst

n o #position #position:

Times and Dates Photo: inya, sxc.hu

y e s DateAndTime + Duration

n o TimeStamp

k in d a Time

s o r ta Date

Cross-Platform Behaviour Consistent Conﬂicting Missing

Unit Slime Grease Tests Consistent Conﬂicting Missing Use it! Avoid it! Add it! (Test it!)

Unit Tests Photo: shadowkill, sxc.hu

Unit Tests 150 131 44 44 20 0 Seaside 2.5 Seaside 2.6 Seaside 2.7 Seaside 2.8 Seaside 3.0

Unit Tests 1,200 1,115 1,050

Slime Lint Tests for Seaside Photo: A Syed, sxc.hu

Rules to detect Portability Issues

a _ 1. b := { a + 2. 3 }. c pairsDo: [ :a :b | a raisedTo: b ]

Rules to detect Seaside Bugs

html div with: ‘Hello World’; id: ‘message’. html updater id: ‘message’; callback: [ :r | html text: ‘Bye’ ]

Grease Platform Compatibility Layer Photo: DarkSide, sxc.hu

Pragmatic

Minimal

Unit Tested

ANSI++

Grease Features Consistent object initialization Consistent exception signalling Common convenience methods Platform-dependent behaviour Unit tests

y e s GRObject class>>#new ^ self basicNew initialize

y e s GRError class>>#signal “VW implementation” ^ self raiseSignal

y e s Object>>#greaseString “Squeak implementation” ^ self asString

y e s#trimLeft #upToLast: #ifNil: #isCollection

y e s GRPlatform current base64Decode: 'aGk='. GRPlatform current addToStartupList: SomeClass. GRPlatform current openDebuggerOn: anException.

Packaging ↑ SUnit Photo: Tory Byrne, www.sxc.hu

73 Packages

Common Seaside-Core

Platform-Speciﬁc Seaside-Pharo-Core

Test Seaside-Tests-Core Seaside-Tests-Pharo-Core

BON US! Find incorrect layer dependencies

Monticello

Monticello Declarative modeling Distributed repositories Optimistic code merging Vendor round-tripping

Monticello ☹ Slow with large repositories ☹ Inconvenient with many packages ☹ Awkward when renaming and moving between packages

Future?

Metacello Declare and load package conﬁgurations Express dependencies on other projects Easily upgrade to newest versions

Mason Automate build process Run tests for each package + dependencies

Monticello2 Faster Per-method version history Better interface for projects with many packages Easier to port? (uses Grease)

book.seaside.st

Summary Write tests! Avoid extended syntax Use ANSI where possible Package out platform-speciﬁc code Slime/Lint for what you can’t use, Grease for what you can

www.seaside.st blog.ﬁtzell.ca jﬁtzell@gmail.com

Seaside Portability

by jfitzell on Dec 12, 2009

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Seaside Portability — Presentation Transcript