Class: SequenceWithSentinel

• Inheritance
• Description
• Class protocol
  • instance creation
• Instance protocol
  • accessing
  • enumeration
  • growing
  • private
  • testing
• Examples

Inheritance:

   Object
   |
   +--Collection
      |
      +--SequenceableCollection
         |
         +--SequenceWithSentinel

Package:

stx:libbasic2

Category:

Collections-Sequenceable

Version:

rev: 1.2 date: 2013/06/25 11:23:55

user: cg

file: SequenceWithSentinel.st directory: libbasic2

module: stx stc-classLibrary: libbasic2

Description:

A collection with a default value for out-of-bounds accessed values.

Class protocol:

 new

(comment from inherited method)
return an instance of myself without indexed variables

 on: aSequence sentinel: anObject

return a new collection based on aSequence but with invalid bounds-accesses returning abObject

Instance protocol:

 at: anIndex

return the element at anIndex, or sentinel if the index is invalid

 at: anIndex put: anObject

(comment from inherited method)
store the 2nd arg, anObject as indexed instvar with index, anInteger.
this method can be redefined in subclasses. Returns anObject (sigh)

 size

answer my size

 do: aBlock

(comment from inherited method)
evaluate the argument, aBlock for every element in the collection in
sequence order.

 grow: howBig

(comment from inherited method)
change the receiver's size

 sentinel: anObject

set the sentinel - the value returned for invalid indices

 sequence: aSequence

set the underlying collection

 sequence: aSequence sentinel: aSentinelValue

set the underlying collection and the sentinel (default)

 isFixedSize

return true if the receiver cannot grow

Examples:

    |coll|

    coll := SequenceWithSentinel on:#(10 20 30 40 50) sentinel:'invalid'.
    Transcript show:'1->'; showCR:(coll at:1).
    Transcript show:'5->'; showCR:(coll at:5).
    Transcript show:'6->'; showCR:(coll at:6).
    coll do:[:each | Transcript showCR:each].