Smalltalk Best Practice Patterns Volume 1: Coding - Free

More documents

Recommendations

Info

Duplicate Removing SetYou have a Collection.How do you remove the duplicates from a Collection?I remember answering this question on a test in school. I know I’ve seen the C-ish code for it whilereviewing code. It always looks ugly:unique := OrderedCollection new.self owners do: [:each | (unique includes: each) ifFalse: [unique add: each]]No need for that in Smalltalk. Once you get over the idea that allocating memory is expensive inprogramming or execution time, and once you get used to the power of the Collection classes,problems like this become trivial.Send “asSet” to the Collection. The result will have all duplicates removed.I sure wish I’d been using Smalltalk when I was in college!When you tune performance, you may find that you are allocating Collections for the sameelements over and over and over. Composing all those intermediate Collections together is no bigdeal. Remember, you’re going for clarity of expression.Use a Temporarily Sorted Collection if you need the unique elements sorted.Coding Patterns page 112 of 147 9/30/2006
Temporarily Sorted CollectionYou have a Collection. You may have implemented a Comparing Method, but want to sort theobjects differently.How do you present a Collection with one of many sort orders?The obvious solution is to store the Collection as a SortedCollection in the first place. Every timeyou change the sort order, you can change the sort block of the SortedCollection.If you wouldn’t otherwise have to have the Collection sorted, this solution causes more problemsthan it solves. You may not want to pay the price of a SortedCollection most of the time. You maywant several sort orders at the same time.You can solve the problem by handing out copies of the Collection. Then you have the problem ofcoordinating additions and removals from the Collection. This problem is usually much less severethan trying to manage several sort orders with the same Collection.Return a sorted copy of the Collection by sending “asSortedCollection” to the Collection.Send “asSortedCollection: aBlock” for custom sort orders.Coding Patterns page 113 of 147 9/30/2006
Page 1 and 2:
Smalltalk Best Practice PatternsVol
Page 3 and 4:
STATE..............................
Page 5 and 6:
PrefaceThis preface will explain wh
Page 7:
AcknowledgmentsI would like to than
Page 10 and 11:
Many of the patterns tell you what
Page 12 and 13:
day to day in development and docum
Page 14 and 15:
What’s Missing?There are a few co
Page 16 and 17:
AdoptionHow can you learn and use t
Page 18 and 19:
Why Patterns WorkHere is the Big As
Page 20 and 21:
Role of PatternsReadingThese patter
Page 22 and 23:
BehaviorObjects model the world thr
Page 24 and 25:
Composed MethodYou are implementing
Page 26 and 27:
Complete Creation MethodA Composed
Page 28 and 29:
ConversionHow do you convert inform
Page 30 and 31:
Converter Creation MethodYou need t
Page 32 and 33:
Query MethodA Composed Method has h
Page 34 and 35:
Execute Around MethodHow do you rep
Page 36 and 37:
MessagesMessages are the heartbeat
Page 38 and 39:
Choosing MessageYou are using a Mes
Page 40 and 41:
Decomposing MessageYou are using a
Page 42 and 43:
Intention Revealing SelectorYou may
Page 44 and 45:
Integer>>addFloat: aFloat^self asFl
Page 46 and 47:
Class: SuperFindingClientsuperclass
Page 48 and 49:
Extending SuperYou are using Super.
Page 50 and 51:
DelegationA Composed Method needs w
Page 52 and 53:
Self DelegationYou are using Delega
Page 54 and 55:
Pluggable BehaviorHow can you param
Page 56 and 57:
Pluggable BlockYou need complex Plu
Page 58 and 59:
marriedMenAndUnmarriedWomen^self ma
Page 60 and 61:
Instance VariablesI wrote the secti
Page 62 and 63: Variable StateHow do you represent
Page 64 and 65: Timer>>defaultMillisecondPeriod^100
Page 66 and 67: Default Value MethodYou have a comp
Page 68 and 69: Direct Variable AccessYou need to a
Page 70 and 71: Getting MethodYou are using Lazy In
Page 72 and 73: Collection Accessor MethodYou are u
Page 74 and 75: Enumeration MethodYou are using Ind
Page 76 and 77: Role Suggesting Instance Variable N
Page 78 and 79: Temporary VariableA Composed Method
Page 80 and 81: Caching Temporary VariableA Perform
Page 82 and 83: Reusing Temporary VariableTemporary
Page 84 and 85: CollectionsThe collection hierarchy
Page 86 and 87: CollectionHow do you represent a on
Page 88 and 89: RunArrayYou are using an OrderedCol
Page 90 and 91: | s |s := Set new.Like an OrderedCo
Page 92 and 93: You may need Double Dispatch for co
Page 94 and 95: DictionaryYou need a Collection tha
Page 96 and 97: SortedCollectionYou have a Collecti
Page 98 and 99: ByteArrayYou need to represent an A
Page 100 and 101: (1 to: anArray size) collect:[:each
Page 102 and 103: IsEmptyHow do you test if a collect
Page 104 and 105: ConcatentationHow do you put two co
Page 106 and 107: DoHow do you execute code for each
Page 108 and 109: Select/RejectHow do you execute cod
Page 110 and 111: Inject:into:You need an Enumeration
Page 114 and 115: StackHow do you implement a stack?O
Page 116 and 117: implementation of queues in Pascal
Page 118 and 119: Lookup CacheHow do you optimize com
Page 120 and 121: Parsing StreamHow do you write a si
Page 122 and 123: ClassesThere is probably no coding
Page 124 and 125: Qualified Subclass NameYou have cre
Page 126 and 127: FormattingNo other topic generates
Page 128 and 129: Type Suggesting Parameter NameYou a
Page 130 and 131: Rectangular BlockYou are writing an
Page 132 and 133: Conditional ExpressionHow do you fo
Page 134 and 135: Simple Enumeration ParameterWhat sh
Page 136 and 137: self listPane parentcolor: Color bl
Page 138 and 139: Point>>printOn: aStreamaStreamprint
Page 140 and 141: Development ExampleIn this chapter,
Page 142 and 143: Money>>setAmount: aNumber currency:
Page 144 and 145: MoneySum>>printOn: aStreammonies do
Page 146: | m1 m2 |m1 := Moneyamount: 5curren
show all

Smalltalk Best Practice Patterns Volume 1: Coding - Free

Create successful ePaper yourself

Delete template?

Save as template?