Object subclass:#InterestConverter
	instanceVariableNames:'destination selector aspect'
	classVariableNames:''
	poolDictionaries:''
	category:'Interface-Support-Models'
!

!InterestConverter class methodsFor:'documentation'!

documentation
"
    instances convert update messages into messages as setup via
    #onChangeSend:to.
    This is a temporary kludge and will be replaced by a more intelligent
    DependencyCollection class in the future.

    [author:]
        Claus Gittinger
"
!

examples
"
  #onChangeSend:to / #retractInterestsIn:
  interested in any change:
                                                                        [exBegin]
    |p b|

    b := [Transcript showCR:'--> notification: point has changed'].

    p := Point new.
    p onChangeSend:#value to:b.
    Delay waitForSeconds:1.
    Transcript showCR:'sending change ...'.
    p changed.
    p retractInterestsFor:b.
    Delay waitForSeconds:1.
    Transcript showCR:'sending change ...'.
    p changed.
                                                                        [exEnd]



  #expressInterestIn:for:sendBack / #retractInterestIn:for:
  interested in a specific change:
                                                                        [exBegin]
     |p b|

     b := [Transcript showCR:'the point changed'].

     p := Point new.
     Transcript showCR:'interest in #foo'.
     p expressInterestIn:#foo for:b sendBack:#value.
     p x:1.
     Transcript showCR:'now changing #bar'.
     p changed:#bar.
     Transcript cr.

     Delay waitForSeconds:1.
     Transcript showCR:'now changing #foo'.
     p changed:#foo.
     Transcript cr.

     Delay waitForSeconds:1.
     Transcript showCR:'no more interest in #foo'.
     p retractInterestIn:#foo for:b.
     Transcript showCR:'now changing #foo'.
     p changed:#foo.
     Transcript cr.

     Delay waitForSeconds:1.
     Transcript showCR:'interest in #bar now'.
     p expressInterestIn:#bar for:b sendBack:#value.
     Transcript showCR:'now changing #foo'.
     p changed:#foo.
     Transcript showCR:'now changing #bar'.
     p changed:#bar.
     Transcript cr.

     Delay waitForSeconds:1.
     Transcript showCR:'interest in #foo now'.
     p expressInterestIn:#foo for:b sendBack:#value.
     Transcript showCR:'now changing #foo'.
     p changed:#foo.
     Transcript showCR:'now changing #bar'.
     p changed:#bar.
     Transcript cr.

     Delay waitForSeconds:1.
     Transcript showCR:'no more interests'.
     p retractInterestsFor:b.
     Transcript showCR:'now changing #foo'.
     p changed:#foo.
     Transcript showCR:'now changing #bar'.
     p changed:#bar.
     Transcript cr.
                                                                        [exEnd]
"
!

history

    "Created: 7.3.1996 / 10:08:55 / cg"
    "Modified: 8.3.1996 / 22:40:11 / cg"
! !

!InterestConverter class methodsFor:'instance creation'!

destination:anObject selector:aSelector
    ^ self basicNew destination:anObject selector:aSelector
!

destination:anObject selector:aSelector aspect:aspect
    ^ self basicNew destination:anObject selector:aSelector aspect:aspect
! !

!InterestConverter methodsFor:'accessing'!

aspect 
    ^ aspect

    "Created: 8.3.1996 / 23:00:37 / cg"
!

destination
    ^ destination

    "Created: 7.3.1996 / 10:57:01 / cg"
!

destination:dest selector:sel
    destination := dest.
    selector := sel

    "Created: 7.3.1996 / 10:49:13 / cg"
!

destination:dest selector:sel aspect:a
    destination := dest.
    selector := sel.
    aspect := a

    "Created: 8.3.1996 / 22:42:03 / cg"
! !

!InterestConverter methodsFor:'change & update'!

update:something with:aParameter from:someObject
    (aspect isNil or:[aspect == something]) ifTrue:[
        destination perform:selector
    ]

    "Created: 7.3.1996 / 10:14:30 / cg"
    "Modified: 8.3.1996 / 22:41:53 / cg"
! !

!InterestConverter class methodsFor:'documentation'!

version
    ^ '$Header: /cvs/stx/stx/libbasic/InterestConverter.st,v 1.5 1996-05-18 15:28:22 cg Exp $'
! !