Smalltalk Best Practice Patterns Volume 1: Coding - Free

Includes:How do you search for a particular element in a collection?Many people’s first instinct is to use the enumeration protocol to implement searching. They willwrite code like this:| found |found := false.aCollection do: [:each | each = anObject ifTrue: [found := true]]....With more experience, you might see a more sophisticated enumeration message:| found |found := (aCollectiondetect: [:each | each = anObject]ifNone: [nil]) notNil....The collection protocol provides you with a message to do exactly this, includes:.The above code would look like this using includes:| found |found := aCollection includes: anObject...You could probably even eliminate the temporary variable and just use the expression in line.Importantly, includes: is available to be optimized. Some kinds of collections, like Set, execute itindependently of the size of the collection. The code fragments above will always take timeproportional to the size of the collection.To search a collection for an object, send includes: and pass the object to be searched for.You will have to implement an Equality Method and a Hashing Method for your own objects if youwant to search based on contents instead of identity.Coding Patterns page 103 of 147 9/30/2006