[Pharo-project] Fwd: hasEqualElements:
Hi
(SortedCollection new addAll: #(9 2 3 ); yourself) hasEqualElements: (OrderedCollection withAll: #(9 2 3)) -> false
hasEqualElements: otherCollection "Answer whether the receiver's size is the same as otherCollection's size, and each of the receiver's elements equal the corresponding element of otherCollection. This should probably replace the current definition of #= ."
| size | (otherCollection isKindOf: SequenceableCollection) ifFalse: [^ false]. (size := self size) = otherCollection size ifFalse: [^ false]. 1 to: size do: [:index | (self at: index) = (otherCollection at: index) ifFalse: [^ false]]. ^ true
For me the name of this method is misleading and I would really like to renaming it hasStructurallyEqualElements: and have new one doing hasEqualElements:
What do you think? I would like a beautiful world....
Stef (freezing with a flu in my bed.... cool christmax).
2009/12/23 Stéphane Ducasse <stephane.ducasse@inria.fr>:
Hi
(SortedCollection new addAll: #(9 2 3 ); yourself) hasEqualElements: (OrderedCollection withAll: #(9 2 3)) -> false
hasEqualElements: otherCollection "Answer whether the receiver's size is the same as otherCollection's size, and each of the receiver's elements equal the corresponding element of otherCollection. This should probably replace the current definition of #= ."
| size | (otherCollection isKindOf: SequenceableCollection) ifFalse: [^ false]. (size := self size) = otherCollection size ifFalse: [^ false]. 1 to: size do: [:index | (self at: index) = (otherCollection at: index) ifFalse: [^ false]]. ^ true
For me the name of this method is misleading and I would really like to renaming it hasStructurallyEqualElements: and have new one doing hasEqualElements:
What do you think? I would like a beautiful world....
Stef (freezing with a flu in my bed.... cool christmax).
Didn't VW had a #isSameSquenceAs: Nicolas
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On Wed, Dec 23, 2009 at 1:08 AM, Nicolas Cellier < nicolas.cellier.aka.nice@gmail.com> wrote:
2009/12/23 Stéphane Ducasse <stephane.ducasse@inria.fr>:
Hi
(SortedCollection new addAll: #(9 2 3 ); yourself) hasEqualElements: (OrderedCollection withAll: #(9 2 3)) -> false
hasEqualElements: otherCollection "Answer whether the receiver's size is the same as otherCollection's size, and each of the receiver's elements equal the corresponding element of otherCollection. This should probably replace the current definition of #= ."
| size | (otherCollection isKindOf: SequenceableCollection) ifFalse: [^ false]. (size := self size) = otherCollection size ifFalse: [^ false]. 1 to: size do: [:index | (self at: index) = (otherCollection at: index) ifFalse: [^ false]]. ^ true
For me the name of this method is misleading and I would really like to renaming it hasStructurallyEqualElements: and have new one doing hasEqualElements:
What do you think? I would like a beautiful world....
Stef (freezing with a flu in my bed.... cool christmax).
Didn't VW had a #isSameSquenceAs:
Yes.
Nicolas
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On Wed, Dec 23, 2009 at 1:08 AM, Nicolas Cellier < nicolas.cellier.aka.nice@gmail.com> wrote:
2009/12/23 Stéphane Ducasse <stephane.ducasse@inria.fr>:
Hi
(SortedCollection new addAll: #(9 2 3 ); yourself) hasEqualElements: (OrderedCollection withAll: #(9 2 3)) -> false
hasEqualElements: otherCollection "Answer whether the receiver's size is the same as otherCollection's size, and each of the receiver's elements equal the corresponding element of otherCollection. This should probably replace the current definition of #= ."
| size | (otherCollection isKindOf: SequenceableCollection) ifFalse: [^ false]. (size := self size) = otherCollection size ifFalse: [^ false]. 1 to: size do: [:index | (self at: index) = (otherCollection at: index) ifFalse: [^ false]]. ^ true
For me the name of this method is misleading and I would really like to renaming it hasStructurallyEqualElements: and have new one doing hasEqualElements:
What do you think? I would like a beautiful world....
Stef (freezing with a flu in my bed.... cool christmax).
Didn't VW had a #isSameSquenceAs:
Nicolas
<methods> <class-id>Core.SequenceableCollection</class-id> <category>comparing</category> <body package="Collections-Abstract" selector="isSameSequenceAs:">isSameSequenceAs: otherCollection "Answer whether the receiver's size is the same as otherCollection's size, and each of the receiver's elements equal the corresponding element of otherCollection." | size | (size := self size) = otherCollection size ifFalse: [^false]. 1 to: size do: [:index | (self at: index) = (otherCollection at: index) ifFalse: [^false]]. ^true</body> </methods> i.e. trust the caller is providing a sequence and if otherCollection doesn't implement at: there will be a run-time error, hence any otherCollection isKindOf: SequenceableCollection is just wasted cycles.
Excellent the Browser did not find it. So now I understand where I got used to the idea of having the difference between sameElements and sameStructuralElements. Tx eliot I will read again in VW. Stef On Dec 23, 2009, at 7:10 PM, Eliot Miranda wrote:
On Wed, Dec 23, 2009 at 1:08 AM, Nicolas Cellier <nicolas.cellier.aka.nice@gmail.com> wrote: 2009/12/23 Stéphane Ducasse <stephane.ducasse@inria.fr>:
Hi
(SortedCollection new addAll: #(9 2 3 ); yourself) hasEqualElements: (OrderedCollection withAll: #(9 2 3)) -> false
hasEqualElements: otherCollection "Answer whether the receiver's size is the same as otherCollection's size, and each of the receiver's elements equal the corresponding element of otherCollection. This should probably replace the current definition of #= ."
| size | (otherCollection isKindOf: SequenceableCollection) ifFalse: [^ false]. (size := self size) = otherCollection size ifFalse: [^ false]. 1 to: size do: [:index | (self at: index) = (otherCollection at: index) ifFalse: [^ false]]. ^ true
For me the name of this method is misleading and I would really like to renaming it hasStructurallyEqualElements: and have new one doing hasEqualElements:
What do you think? I would like a beautiful world....
Stef (freezing with a flu in my bed.... cool christmax).
Didn't VW had a #isSameSquenceAs:
Nicolas
<methods> <class-id>Core.SequenceableCollection</class-id> <category>comparing</category>
<body package="Collections-Abstract" selector="isSameSequenceAs:">isSameSequenceAs: otherCollection "Answer whether the receiver's size is the same as otherCollection's size, and each of the receiver's elements equal the corresponding element of otherCollection."
| size | (size := self size) = otherCollection size ifFalse: [^false]. 1 to: size do: [:index | (self at: index) = (otherCollection at: index) ifFalse: [^false]]. ^true</body> </methods>
i.e. trust the caller is providing a sequence and if otherCollection doesn't implement at: there will be a run-time error, hence any otherCollection isKindOf: SequenceableCollection is just wasted cycles. _______________________________________________ Pharo-project mailing list Pharo-project@lists.gforge.inria.fr http://lists.gforge.inria.fr/cgi-bin/mailman/listinfo/pharo-project
Em 23/12/2009 16:10, Eliot Miranda < eliot.miranda@gmail.com > escreveu:
Core.SequenceableCollection comparing isSameSequenceAs: otherCollection
"Answer whether the receiver's size is the same as otherCollection's size, and each of the receiver's elements equal the corresponding element of otherCollection."
| size | (size := self size) = otherCollection size ifFalse: [^false]. 1 to: size do: [:index | (self at: index) = (otherCollection at: index) ifFalse: [^false]]. ^true
i.e. trust the caller is providing a sequence and if otherCollection doesn't implement at: there will be a run-time error, hence any otherCollection isKindOf: SequenceableCollection is just wasted cycles.
I don't think that "trusting the caller" makes sense in this case, so I propose instead that you implementation be complemented by: Object>>isSameSequenceAs: otherCollection ^false -- Cesar Rabak
On Wed, Dec 23, 2009 at 10:41 AM, <csrabak@bol.com.br> wrote:
Em 23/12/2009 16:10, Eliot Miranda < eliot.miranda@gmail.com > escreveu:
Core.SequenceableCollection comparing isSameSequenceAs: otherCollection
"Answer whether the receiver's size is the same as otherCollection's size, and each of the receiver's elements equal the corresponding element of otherCollection."
| size | (size := self size) = otherCollection size ifFalse: [^false]. 1 to: size do: [:index | (self at: index) = (otherCollection at: index) ifFalse: [^false]]. ^true
i.e. trust the caller is providing a sequence and if otherCollection doesn't implement at: there will be a run-time error, hence any otherCollection isKindOf: SequenceableCollection is just wasted cycles.
I don't think that "trusting the caller" makes sense in this case, so I propose instead that you implementation be complemented by:
Object>>isSameSequenceAs: otherCollection ^false
We're talking about the argument otherCollection not the receiver. i.e. leaving out isKindOf: in isSameSequenceAs: otherCollection "Answer whether the receiver's size is the same as otherCollection's size, and each of the receiver's elements equal the corresponding element of otherCollection." | size | (otherCollection isKindOf: SequenceableCollection) ifFalse: [^false]. "this is a horrible wart" (size := self size) = otherCollection size ifFalse: [^false]. 1 to: size do: [:index | (self at: index) = (otherCollection at: index) ifFalse: [^false]]. ^true You could use double dispatching: SequenceableCollection>>isSameSequenceAs: otherThing ^otherThing isSameSequenceAsSequence: self SequenceableCollection>> isSameSequenceAsSequence: aSequenceableCollection aSequenceableCollection size ~= self size ifTrue: [^false]. etc Object isSameSequenceAsSequence: aSequenceableCollection ^false but I think in this case it's overkill.
-- Cesar Rabak
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Ideally what I would like is = isSameSequenceAs: + same receiver kind (may be overkill) isSameSequenceAs: otherCollection "Answer whether the receiver's size is the same as otherCollection's size, and each of the receiver's elements equal the corresponding element of otherCollection." hasSameElements: "Answer whether the receiver's size is the same as otherCollection's size, and each of the receiver's elements is included in otherCollection and vice versa." Stef On Dec 23, 2009, at 7:58 PM, Eliot Miranda wrote:
On Wed, Dec 23, 2009 at 10:41 AM, <csrabak@bol.com.br> wrote: Em 23/12/2009 16:10, Eliot Miranda < eliot.miranda@gmail.com > escreveu:
Core.SequenceableCollection comparing isSameSequenceAs: otherCollection
"Answer whether the receiver's size is the same as otherCollection's size, and each of the receiver's elements equal the corresponding element of otherCollection."
| size | (size := self size) = otherCollection size ifFalse: [^false]. 1 to: size do: [:index | (self at: index) = (otherCollection at: index) ifFalse: [^false]]. ^true
i.e. trust the caller is providing a sequence and if otherCollection doesn't implement at: there will be a run-time error, hence any otherCollection isKindOf: SequenceableCollection is just wasted cycles.
I don't think that "trusting the caller" makes sense in this case, so I propose instead that you implementation be complemented by:
Object>>isSameSequenceAs: otherCollection ^false
We're talking about the argument otherCollection not the receiver. i.e. leaving out isKindOf: in isSameSequenceAs: otherCollection "Answer whether the receiver's size is the same as otherCollection's size, and each of the receiver's elements equal the corresponding element of otherCollection."
| size | (otherCollection isKindOf: SequenceableCollection) ifFalse: [^false]. "this is a horrible wart" (size := self size) = otherCollection size ifFalse: [^false]. 1 to: size do: [:index | (self at: index) = (otherCollection at: index) ifFalse: [^false]]. ^true
You could use double dispatching:
SequenceableCollection>>isSameSequenceAs: otherThing ^otherThing isSameSequenceAsSequence: self
SequenceableCollection>> isSameSequenceAsSequence: aSequenceableCollection aSequenceableCollection size ~= self size ifTrue: [^false]. etc
Object isSameSequenceAsSequence: aSequenceableCollection ^false
but I think in this case it's overkill.
-- Cesar Rabak
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2009/12/23 Stéphane Ducasse <stephane.ducasse@inria.fr>:
Ideally what I would like is
=     isSameSequenceAs: + same receiver kind          (may be overkill)
isSameSequenceAs: otherCollection     "Answer whether the receiver's size is the same as otherCollection's size, and each     of the receiver's elements equal the corresponding element of otherCollection."
hasSameElements:     "Answer whether the receiver's size is the same as otherCollection's size, and each     of the receiver's elements is included in otherCollection and vice versa."
Stef
like #(2 2 3) hasSameElements: #(2 3 3) -> true but #(2 2 3) asSet hasSameElements: #(2 3 3) -> false ?
On Dec 23, 2009, at 7:58 PM, Eliot Miranda wrote:
On Wed, Dec 23, 2009 at 10:41 AM, <csrabak@bol.com.br> wrote: Em 23/12/2009 16:10, Eliot Miranda < eliot.miranda@gmail.com > escreveu:
 Core.SequenceableCollection comparing  isSameSequenceAs: otherCollection
 "Answer whether the receiver's size is the same as otherCollection's  size, and each of the receiver's elements equal the corresponding  element of otherCollection."
 | size |  (size := self size) = otherCollection size ifFalse: [^false].  1 to: size do: [:index |  (self at: index) = (otherCollection at: index) ifFalse: [^false]].  ^true
 i.e.  trust  the  caller  is  providing  a  sequence  and  if otherCollection  doesn't  implement at:  there  will  be a  run-time error, hence any otherCollection isKindOf: SequenceableCollection is just wasted cycles.
I don't think that "trusting the caller" makes sense in this case, so I propose instead that you implementation be complemented by:
Object>>isSameSequenceAs: otherCollection ^false
We're talking about the argument otherCollection not the receiver.  i.e. leaving out isKindOf: in isSameSequenceAs: otherCollection      "Answer whether the receiver's size is the same as otherCollection's size, and each      of the receiver's elements equal the corresponding element of otherCollection."
     | size |      (otherCollection isKindOf: SequenceableCollection) ifFalse: [^false]. "this is a horrible wart"      (size := self size) = otherCollection size ifFalse: [^false].      1 to: size do: [:index |          (self at: index) = (otherCollection at: index) ifFalse: [^false]].      ^true
You could use double dispatching:
SequenceableCollection>>isSameSequenceAs: otherThing   ^otherThing isSameSequenceAsSequence: self
SequenceableCollection>> isSameSequenceAsSequence: aSequenceableCollection   aSequenceableCollection size ~= self size ifTrue: [^false].   etc
Object isSameSequenceAsSequence: aSequenceableCollection   ^false
but I think in this case it's overkill.
-- Cesar Rabak
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2009/12/23 Stéphane Ducasse <stephane.ducasse@inria.fr>:
Ideally what I would like is
= isSameSequenceAs: + same receiver kind (may be overkill)
isSameSequenceAs: otherCollection "Answer whether the receiver's size is the same as otherCollection's size, and each of the receiver's elements equal the corresponding element of otherCollection."
hasSameElements: "Answer whether the receiver's size is the same as otherCollection's size, and each of the receiver's elements is included in otherCollection and vice versa."
Stef
like #(2 2 3) hasSameElements: #(2 3 3) -> true but #(2 2 3) asSet hasSameElements: #(2 3 3) -> false
no as
hasSameElements: "Answer wether each of the receiver's elements is included in otherCollection and vice versa."
Sorry another victim of copy and paste. Stef
?
On Dec 23, 2009, at 7:58 PM, Eliot Miranda wrote:
On Wed, Dec 23, 2009 at 10:41 AM, <csrabak@bol.com.br> wrote: Em 23/12/2009 16:10, Eliot Miranda < eliot.miranda@gmail.com > escreveu:
Core.SequenceableCollection comparing isSameSequenceAs: otherCollection
"Answer whether the receiver's size is the same as otherCollection's size, and each of the receiver's elements equal the corresponding element of otherCollection."
| size | (size := self size) = otherCollection size ifFalse: [^false]. 1 to: size do: [:index | (self at: index) = (otherCollection at: index) ifFalse: [^false]]. ^true
i.e. trust the caller is providing a sequence and if otherCollection doesn't implement at: there will be a run-time error, hence any otherCollection isKindOf: SequenceableCollection is just wasted cycles.
I don't think that "trusting the caller" makes sense in this case, so I propose instead that you implementation be complemented by:
Object>>isSameSequenceAs: otherCollection ^false
We're talking about the argument otherCollection not the receiver. i.e. leaving out isKindOf: in isSameSequenceAs: otherCollection "Answer whether the receiver's size is the same as otherCollection's size, and each of the receiver's elements equal the corresponding element of otherCollection."
| size | (otherCollection isKindOf: SequenceableCollection) ifFalse: [^false]. "this is a horrible wart" (size := self size) = otherCollection size ifFalse: [^false]. 1 to: size do: [:index | (self at: index) = (otherCollection at: index) ifFalse: [^false]]. ^true
You could use double dispatching:
SequenceableCollection>>isSameSequenceAs: otherThing ^otherThing isSameSequenceAsSequence: self
SequenceableCollection>> isSameSequenceAsSequence: aSequenceableCollection aSequenceableCollection size ~= self size ifTrue: [^false]. etc
Object isSameSequenceAsSequence: aSequenceableCollection ^false
but I think in this case it's overkill.
-- Cesar Rabak
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Em 23/12/2009 19:17, Nicolas Cellier < nicolas.cellier.aka.nice@gmail.com > escreveu:
2009/12/23 Stéphane Ducasse :
Ideally what I would like is
= isSameSequenceAs: + same receiver kind (may be overkill)
isSameSequenceAs: otherCollection "Answer whether the receiver's size is the same as otherCollection's size, and each of the receiver's elements equal the corresponding element of otherCollection."
hasSameElements: "Answer whether the receiver's size is the same as otherCollection's size, and each of the receiver's elements is included in otherCollection and vice versa." Stef
like #(2 2 3) hasSameElements: #(2 3 3) -> true
but #(2 2 3) asSet hasSameElements: #(2 3 3) -> false
Can someone illustrate this less enlightened coder what common programming pattern this wonderful method would of use for? -- Cesar Rabak
Eliot is right: the argument of isSameSequenceAs: should be already of SequenceableCollection kind , otherwise there is no sense asking , whether some collection has same sequence as another one, which probably not sequencable. By analogy, asking 'isSameColor: anObject' , we already stating, that an argument - anObject having a #color property. Otherwise, if its not, this should lead to error, but not returning 'false'. 2009/12/23 Eliot Miranda <eliot.miranda@gmail.com>:
On Wed, Dec 23, 2009 at 10:41 AM, <csrabak@bol.com.br> wrote:
Em 23/12/2009 16:10, Eliot Miranda < eliot.miranda@gmail.com > escreveu:
 Core.SequenceableCollection comparing  isSameSequenceAs: otherCollection
 "Answer whether the receiver's size is the same as otherCollection's  size, and each of the receiver's elements equal the corresponding  element of otherCollection."
 | size |  (size := self size) = otherCollection size ifFalse: [^false].  1 to: size do: [:index |  (self at: index) = (otherCollection at: index) ifFalse: [^false]].  ^true
 i.e.  trust  the  caller  is  providing  a  sequence  and  if otherCollection  doesn't  implement at:  there  will  be a  run-time error, hence any otherCollection isKindOf: SequenceableCollection is just wasted cycles.
I don't think that "trusting the caller" makes sense in this case, so I propose instead that you implementation be complemented by:
Object>>isSameSequenceAs: otherCollection ^false
We're talking about the argument otherCollection not the receiver.  i.e. leaving out isKindOf: in isSameSequenceAs: otherCollection      "Answer whether the receiver's size is the same as otherCollection's size, and each       of the receiver's elements equal the corresponding element of otherCollection."
     | size |      (otherCollection isKindOf: SequenceableCollection) ifFalse: [^false]. "this is a horrible wart"      (size := self size) = otherCollection size ifFalse: [^false].      1 to: size do: [:index |          (self at: index) = (otherCollection at: index) ifFalse: [^false]].      ^true You could use double dispatching: SequenceableCollection>>isSameSequenceAs: otherThing    ^otherThing isSameSequenceAsSequence: self SequenceableCollection>> isSameSequenceAsSequence: aSequenceableCollection    aSequenceableCollection size ~= self size ifTrue: [^false].    etc Object isSameSequenceAsSequence: aSequenceableCollection    ^false but I think in this case it's overkill.
-- Cesar Rabak
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-- Best regards, Igor Stasenko AKA sig.
Igor, Sometimes a fallacy can be written by clever people, by accident. If you pay attention to the line: (size := self size) = otherCollection size ifFalse: [^false]. I all Smalltalks [Except Pharo to what I wrote a comment in issue 1637 http://code.google.com/p/pharo/issues/detail?id=1637] this would return false if self be not Collection or otheCollection isKindOf: Collection not. This happens because in these Smalltalks Object>>size returns zero. In Squeak where the method is implemented slightly different, an UndefinedObject>>size does return the zero for nil Objects but will raise an error for non indexable objects. So except if we are willing to have a very specific dialect of Smalltalk in Pharo, we'll probably have to fix the protocol for Object>>size, and then the line above will for most of the cases automatically return false as soon otherCollection happen to be isKindOf: Collection not. OTOH, if we keep Pharo as is, the above line will also by the automatism already described give the MNU as an error. . . -- Cesar Rabak Em 23/12/2009 20:22, Igor Stasenko <siguctua@gmail.com> escreveu: Eliot is right: the argument of isSameSequenceAs: should be already of SequenceableCollection kind , otherwise there is no sense asking , whether some collection has same sequence as another one, which probably not sequencable. By analogy, asking 'isSameColor: anObject' , we already stating, that an argument - anObject having a #color property. Otherwise, if its not, this should lead to error, but not returning 'false'. 2009/12/23 Eliot Miranda :
On Wed, Dec 23, 2009 at 10:41 AM, wrote:
Em 23/12/2009 16:10, Eliot Miranda < eliot.miranda@gmail.com > escreveu:
 Core.SequenceableCollection comparing  isSameSequenceAs: otherCollection
 "Answer whether the receiver's size is the same as otherCollection's  size, and each of the receiver's elements equal the corresponding  element of otherCollection."
 | size |  (size := self size) = otherCollection size ifFalse: [^false].  1 to: size do: [:index |  (self at: index) = (otherCollection at: index) ifFalse: [^false]].  ^true
 i.e.  trust  the  caller  is  providing  a  sequence  and  if otherCollection  doesn't  implement at:  there  will  be a  run-time error, hence any otherCollection isKindOf: SequenceableCollection is just wasted cycles.
I don't think that "trusting the caller" makes sense in this case, so I propose instead that you implementation be complemented by:
Object>>isSameSequenceAs: otherCollection ^false
We're talking about the argument otherCollection not the receiver.  i.e. leaving out isKindOf: in isSameSequenceAs: otherCollection      "Answer whether the receiver's size is the same as otherCollection's size, and each       of the receiver's elements equal the corresponding element of otherCollection."
     | size |      (otherCollection isKindOf: SequenceableCollection) ifFalse: [^false]. "this is a horrible wart"      (size := self size) = otherCollection size ifFalse: [^false].      1 to: size do: [:index |          (self at: index) = (otherCollection at: index) ifFalse: [^false]].      ^true You could use double dispatching: SequenceableCollection>>isSameSequenceAs: otherThing    ^otherThing isSameSequenceAsSequence: self SequenceableCollection>> isSameSequenceAsSequence: aSequenceableCollection    aSequenceableCollection size ~= self size ifTrue: [^false].    etc Object isSameSequenceAsSequence: aSequenceableCollection    ^false but I think in this case it's overkill.
-- Cesar Rabak
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-- Best regards, Igor Stasenko AKA sig. _______________________________________________ Pharo-project mailing list Pharo-project@lists.gforge.inria.fr http://lists.gforge.inria.fr/cgi-bin/mailman/listinfo/pharo-project
2009/12/24 <csrabak@bol.com.br>:
Igor,
Sometimes a fallacy can be written by clever people, by accident.
If you pay attention to the line:
(size := self size) = otherCollection size ifFalse: [^false].
I all Smalltalks [Except Pharo to what I wrote a comment in issue 1637 http://code.google.com/p/pharo/issues/detail?id=1637] this would return false if self be not Collection or otheCollection isKindOf: Collection not.
This happens because in these Smalltalks Object>>size returns zero.
Not so sure. Try 1.0 size, then 1.0 at: 1.0 size in you favourite dialect. Nicolas
In Squeak where the method is implemented slightly different, an UndefinedObject>>size does return the zero for nil Objects but will raise an error for non indexable objects.
So except if we are willing to have a very specific dialect of Smalltalk in Pharo, we'll probably have to fix the protocol for Object>>size, and then the line above will for most of the cases automatically return false as soon otherCollection happen to be isKindOf: Collection not.
OTOH, if we keep Pharo as is, the above line will also by the automatism already described give the MNU as an error. . .
-- Cesar Rabak
Em 23/12/2009 20:22, Igor Stasenko <siguctua@gmail.com> escreveu:
Eliot is right: the argument of isSameSequenceAs: should be already of SequenceableCollection kind , otherwise there is no sense asking , whether some collection has same sequence as another one, which probably not sequencable.
By analogy, asking  'isSameColor: anObject' , we already stating, that an argument - anObject having a #color property. Otherwise, if its not, this should lead to error, but not returning 'false'.
2009/12/23 Eliot Miranda :
On Wed, Dec 23, 2009 at 10:41 AM, Â wrote:
Em 23/12/2009 16:10, Eliot Miranda < eliot.miranda@gmail.com > escreveu:
 Core.SequenceableCollection comparing  isSameSequenceAs: otherCollection
 "Answer whether the receiver's size is the same as otherCollection's  size, and each of the receiver's elements equal the corresponding  element of otherCollection."
 | size |  (size := self size) = otherCollection size ifFalse: [^false].  1 to: size do: [:index |  (self at: index) = (otherCollection at: index) ifFalse: [^false]].  ^true
 i.e.  trust  the  caller  is  providing  a  sequence  and  if otherCollection  doesn't  implement at:  there  will  be a  run-time error, hence any otherCollection isKindOf: SequenceableCollection is just wasted cycles.
I don't think that "trusting the caller" makes sense in this case, so I propose instead that you implementation be complemented by:
Object>>isSameSequenceAs: otherCollection ^false
We're talking about the argument otherCollection not the receiver.  i.e. leaving out isKindOf: in isSameSequenceAs: otherCollection      "Answer whether the receiver's size is the same as otherCollection's size, and each       of the receiver's elements equal the corresponding element of otherCollection."
     | size |      (otherCollection isKindOf: SequenceableCollection) ifFalse: [^false]. "this is a horrible wart"      (size := self size) = otherCollection size ifFalse: [^false].      1 to: size do: [:index |          (self at: index) = (otherCollection at: index) ifFalse: [^false]].      ^true You could use double dispatching: SequenceableCollection>>isSameSequenceAs: otherThing    ^otherThing isSameSequenceAsSequence: self SequenceableCollection>> isSameSequenceAsSequence: aSequenceableCollection    aSequenceableCollection size ~= self size ifTrue: [^false].    etc Object isSameSequenceAsSequence: aSequenceableCollection    ^false but I think in this case it's overkill.
-- Cesar Rabak
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Em 23/12/2009 22:51, Nicolas Cellier <nicolas.cellier.aka.nice@gmail.com> escreveu:
2009/12/24 :
Igor, Sometimes a fallacy can be written by clever people, by accident. If you pay attention to the line: (size := self size) = otherCollection size ifFalse: [^false]. I all Smalltalks [Except Pharo to what I wrote a comment in issue 1637 http://code.google.com/p/pharo/issues/detail?id=1637] this would return false if self be not Collection or otheCollection isKindOf: Collection not. This happens because in these Smalltalks Object>>size returns zero.
Not so sure. Try 1.0 size, then 1.0 at: 1.0 size in you favourite dialect.
Nicolas, In Squeak 3.10.2-7179: 1.0 size -> 2 "OK I'm surprised here" 1.0 at: 1.0 size -> 0 "this will not work anymore in Pharo because indices have to be Integer in Pharo right now" HTH -- Cesar Rabak
2009/12/24 <csrabak@bol.com.br>:
Em 23/12/2009 22:51, Nicolas Cellier <nicolas.cellier.aka.nice@gmail.com> escreveu:
 2009/12/24 :
Igor, Sometimes a fallacy can be written by clever people, by accident. If you pay attention to the line: (size := self size) = otherCollection size ifFalse: [^false]. I all Smalltalks [Except Pharo to  what I wrote a comment in issue 1637  http://code.google.com/p/pharo/issues/detail?id=1637]  this would  return false if  self be  not Collection  or otheCollection isKindOf: Collection not. This  happens  because in  these  Smalltalks Object>>size  returns zero.
 Not so sure.  Try 1.0 size,  then 1.0 at: 1.0 size in you favourite dialect.
Nicolas,
In Squeak 3.10.2-7179:
1.0 size -> 2 "OK I'm surprised here"
1.0 at: 1.0 size -> 0 "this will not work anymore in Pharo because indices have to be Integer in Pharo right now"
I mean in VW, size would be > 0 but #at: would raise a debugger. Nicolas
HTH
-- Cesar Rabak
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On Thu, 24 Dec 2009, csrabak@bol.com.br wrote:
Em 23/12/2009 22:51, Nicolas Cellier <nicolas.cellier.aka.nice@gmail.com> escreveu:
2009/12/24 :
Igor, Sometimes a fallacy can be written by clever people, by accident. If you pay attention to the line: (size := self size) = otherCollection size ifFalse: [^false]. I all Smalltalks [Except Pharo to what I wrote a comment in issue 1637 http://code.google.com/p/pharo/issues/detail?id=1637] this would return false if self be not Collection or otheCollection isKindOf: Collection not. This happens because in these Smalltalks Object>>size returns zero.
Not so sure. Try 1.0 size, then 1.0 at: 1.0 size in you favourite dialect.
Nicolas,
In Squeak 3.10.2-7179:
1.0 size -> 2 "OK I'm surprised here"
It's not surprising since Float is a variable word subclass of Number. :)
1.0 at: 1.0 size -> 0 "this will not work anymore in Pharo because indices have to be Integer in Pharo right now"
The index is 2, so it will work. Btw, I wonder how pharo can force Integer indices if the vm accepts Floats too. Levente
HTH
-- Cesar Rabak
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Em 24/12/2009 01:21, Levente Uzonyi < leves@elte.hu > escreveu:
On Thu, 24 Dec 2009, csrabak@bol.com.br wrote:
Em 23/12/2009 22:51, Nicolas Cellier escreveu:
2009/12/24 :
Igor, Sometimes a fallacy can be written by clever people, by accident. If you pay attention to the line: (size := self size) = otherCollection size ifFalse: [^false]. I all Smalltalks [Except Pharo to what I wrote a comment in issue 1637 http://code.google.com/p/pharo/issues/detail?id=1637] this would return false if self be not Collection or otheCollection isKindOf: Collection not. This happens because in these Smalltalks Object>>size returns zero. Not so sure. Try 1.0 size, then 1.0 at: 1.0 size in you favourite dialect. Nicolas, In Squeak 3.10.2-7179: 1.0 size -> 2 "OK I'm surprised here" It's not surprising since Float is a variable word subclass of Number. :)
1.0 at: 1.0 size -> 0 "this will not work anymore in Pharo because indices have to be Integer in Pharo right now" The index is 2, so it will work. Btw, I wonder how pharo can force Integer indices if the vm accepts Floats too.
Levente, In fact VM _does_ _not_ accept Floats as indices. There is a hack in Squeak code (which in fact contradicts the comment in the method) in the #at: methods that make a conversion from Number to Integer. If you comment that code out you'll see the VM #at: (via the primitive) will fail with Floats. -- Cesar Rabak
On Thu, 24 Dec 2009, csrabak@bol.com.br wrote:
Em 24/12/2009 01:21, Levente Uzonyi < leves@elte.hu > escreveu:
On Thu, 24 Dec 2009, csrabak@bol.com.br wrote:
Em 23/12/2009 22:51, Nicolas Cellier escreveu:
2009/12/24 :
Igor, Sometimes a fallacy can be written by clever people, by accident. If you pay attention to the line: (size := self size) = otherCollection size ifFalse: [^false]. I all Smalltalks [Except Pharo to what I wrote a comment in issue 1637 http://code.google.com/p/pharo/issues/detail?id=1637] this would return false if self be not Collection or otheCollection isKindOf: Collection not. This happens because in these Smalltalks Object>>size returns zero. Not so sure. Try 1.0 size, then 1.0 at: 1.0 size in you favourite dialect. Nicolas, In Squeak 3.10.2-7179: 1.0 size -> 2 "OK I'm surprised here" It's not surprising since Float is a variable word subclass of Number. :)
1.0 at: 1.0 size -> 0 "this will not work anymore in Pharo because indices have to be Integer in Pharo right now" The index is 2, so it will work. Btw, I wonder how pharo can force Integer indices if the vm accepts Floats too.
Levente,
In fact VM _does_ _not_ accept Floats as indices. There is a hack in Squeak code (which in fact contradicts the comment in the method) in the #at: methods that make a conversion from Number to Integer.
If you comment that code out you'll see the VM #at: (via the primitive) will fail with Floats.
True, and cool, since this hack can be removed. Now I wonder why did I assume that the vm has this hack. :) Levente
-- Cesar Rabak
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On Thu, Dec 24, 2009 at 12:21 PM, Levente Uzonyi <leves@elte.hu> wrote:
On Thu, 24 Dec 2009, csrabak@bol.com.br wrote:
Em 24/12/2009 01:21, Levente Uzonyi < leves@elte.hu > escreveu:
On Thu, 24 Dec 2009, csrabak@bol.com.br wrote:
Em 23/12/2009 22:51, Nicolas Cellier escreveu:
2009/12/24 :
Igor, Sometimes a fallacy can be written by clever people, by accident. If you pay attention to the line: (size := self size) = otherCollection size ifFalse: [^false]. I all Smalltalks [Except Pharo to what I wrote a comment in issue 1637 http://code.google.com/p/pharo/issues/detail?id=1637] this would return false if self be not Collection or otheCollection isKindOf: Collection not. This happens because in these Smalltalks Object>>size returns zero. Not so sure. Try 1.0 size, then 1.0 at: 1.0 size in you favourite dialect. Nicolas, In Squeak 3.10.2-7179: 1.0 size -> 2 "OK I'm surprised here" It's not surprising since Float is a variable word subclass of Number. :)
1.0 at: 1.0 size -> 0 "this will not work anymore in Pharo because indices have to be Integer in Pharo right now" The index is 2, so it will work. Btw, I wonder how pharo can force Integer indices if the vm accepts Floats too.
Levente,
In fact VM _does_ _not_ accept Floats as indices. There is a hack in Squeak code (which in fact contradicts the comment in the method) in the #at: methods that make a conversion from Number to Integer.
If you comment that code out you'll see the VM #at: (via the primitive) will fail with Floats.
True, and cool, since this hack can be removed. Now I wonder why did I assume that the vm has this hack. :)
This 'hack' is as old as Smalltalk-80 V2 and is AFAICT in all Smalltalk-80 derived Smalltalks: !Object methodsFor: 'accessing'! at: index "Answer the value of an indexable field in the receiver. Fail if the argument index is not an Integer or is out of bounds. Essential. See documentation in Object metaclass." <primitive: 60> index isInteger ifTrue: [self errorSubscriptBounds: index]. (index isKindOf: Number) ifTrue: [^self at: index truncated] ifFalse: [self errorNonIntegerIndex]! It is also free in the sense that the failure code is only invoked when the primitive fails and so adds nothing to the cost of successful accesses, which are the high dynamic frequency operation. It will also show up under profiling if one is concerned about efficiency, and so isn't a hidden cost. It is also in keeping with Smalltalk's mixed mode/arbitrary precision implicit coercion number system that one *can* use fractions or floats as indices. Stripping out coercions like this will make the system more brittle. So please do *not* remove this "hack". I think it's a feature and a useful one.
Levente
-- Cesar Rabak
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On Thu, 24 Dec 2009, Eliot Miranda wrote:
This 'hack' is as old as Smalltalk-80 V2 and is AFAICT in all Smalltalk-80 derived Smalltalks:
!Object methodsFor: 'accessing'! at: index "Answer the value of an indexable field in the receiver. Fail if the argument index is not an Integer or is out of bounds. Essential. See documentation in Object metaclass."
<primitive: 60> index isInteger ifTrue: [self errorSubscriptBounds: index]. (index isKindOf: Number) ifTrue: [^self at: index truncated] ifFalse: [self errorNonIntegerIndex]!
It is also free in the sense that the failure code is only invoked when the primitive fails and so adds nothing to the cost of successful accesses, which are the high dynamic frequency operation. It will also show up under profiling if one is concerned about efficiency, and so isn't a hidden cost.
It is also in keeping with Smalltalk's mixed mode/arbitrary precision implicit coercion number system that one *can* use fractions or floats as indices.
Stripping out coercions like this will make the system more brittle. So please do *not* remove this "hack". I think it's a feature and a useful one.
Can you give me an example that demonstrates the usefulness of this feature? Levente
On Thu, Dec 24, 2009 at 2:52 PM, Levente Uzonyi <leves@elte.hu> wrote:
On Thu, 24 Dec 2009, Eliot Miranda wrote:
This 'hack' is as old as Smalltalk-80 V2 and is AFAICT in all
Smalltalk-80
derived Smalltalks:
!Object methodsFor: 'accessing'! at: index "Answer the value of an indexable field in the receiver. Fail if the argument index is not an Integer or is out of bounds. Essential. See documentation in Object metaclass."
<primitive: 60> index isInteger ifTrue: [self errorSubscriptBounds: index]. (index isKindOf: Number) ifTrue: [^self at: index truncated] ifFalse: [self errorNonIntegerIndex]!
It is also free in the sense that the failure code is only invoked when the primitive fails and so adds nothing to the cost of successful accesses, which are the high dynamic frequency operation. It will also show up under profiling if one is concerned about efficiency, and so isn't a hidden cost.
It is also in keeping with Smalltalk's mixed mode/arbitrary precision implicit coercion number system that one *can* use fractions or floats as indices.
Stripping out coercions like this will make the system more brittle. So please do *not* remove this "hack". I think it's a feature and a useful one.
Can you give me an example that demonstrates the usefulness of this feature?
| a r | a := Array new: 10 withAll: 0. r := Random new. 100 timesRepeat: [| v | v := r next * 10 + 1. a at: v put: (a at: v) + 1]. a i.e. I didn't have to provide an explicit rounding step. That's useful. But in general anywhere where an index is derived by some calculation not having to provide the rounding step could be useful/helpful/more concise. e.g. (n roundTo: 0.1) * 10 vs ((n roundTo: 0.1) * 10) asInteger. Some thought went into the original choice. It is not a hack but there by intent. The integers are simply a subset of the reals and forcing the programmer to use them is favouring the machine above the programmer. But I think you should justify getting rid of it rather than my having to justify keeping it. Getting rid of it risks breaking code. If it is there but does not harm then why get rid of it? best Eliot
Levente
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thanks for the explanation. I will add this in the method comment and probably class comment http://code.google.com/p/pharo/issues/detail?id=1685 Stef On Dec 25, 2009, at 1:11 AM, Eliot Miranda wrote:
On Thu, Dec 24, 2009 at 2:52 PM, Levente Uzonyi <leves@elte.hu> wrote: On Thu, 24 Dec 2009, Eliot Miranda wrote:
This 'hack' is as old as Smalltalk-80 V2 and is AFAICT in all Smalltalk-80 derived Smalltalks:
!Object methodsFor: 'accessing'! at: index "Answer the value of an indexable field in the receiver. Fail if the argument index is not an Integer or is out of bounds. Essential. See documentation in Object metaclass."
<primitive: 60> index isInteger ifTrue: [self errorSubscriptBounds: index]. (index isKindOf: Number) ifTrue: [^self at: index truncated] ifFalse: [self errorNonIntegerIndex]!
It is also free in the sense that the failure code is only invoked when the primitive fails and so adds nothing to the cost of successful accesses, which are the high dynamic frequency operation. It will also show up under profiling if one is concerned about efficiency, and so isn't a hidden cost.
It is also in keeping with Smalltalk's mixed mode/arbitrary precision implicit coercion number system that one *can* use fractions or floats as indices.
Stripping out coercions like this will make the system more brittle. So please do *not* remove this "hack". I think it's a feature and a useful one.
Can you give me an example that demonstrates the usefulness of this feature?
| a r | a := Array new: 10 withAll: 0. r := Random new. 100 timesRepeat: [| v | v := r next * 10 + 1. a at: v put: (a at: v) + 1]. a
i.e. I didn't have to provide an explicit rounding step. That's useful. But in general anywhere where an index is derived by some calculation not having to provide the rounding step could be useful/helpful/more concise. e.g. (n roundTo: 0.1) * 10 vs ((n roundTo: 0.1) * 10) asInteger.
Some thought went into the original choice. It is not a hack but there by intent. The integers are simply a subset of the reals and forcing the programmer to use them is favouring the machine above the programmer.
But I think you should justify getting rid of it rather than my having to justify keeping it. Getting rid of it risks breaking code. If it is there but does not harm then why get rid of it?
best Eliot
Levente
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I've put some comments in the issue #1685. Em 25/12/2009 08:02, Stéphane Ducasse < stephane.ducasse@inria.fr > escreveu: thanks for the explanation. I will add this in the method comment and probably class comment http://code.google.com/p/pharo/issues/detail?id=1685 Stef
2009/12/25 Levente Uzonyi <leves@elte.hu>:
On Thu, 24 Dec 2009, Eliot Miranda wrote:
This 'hack' is as old as Smalltalk-80 V2 and is AFAICT in all Smalltalk-80 derived Smalltalks:
!Object methodsFor: 'accessing'! at: index   "Answer the value of an indexable field in the receiver. Fail if the   argument index is not an Integer or is out of bounds. Essential. See   documentation in Object metaclass."
  <primitive: 60>   index isInteger     ifTrue: [self errorSubscriptBounds: index].   (index isKindOf: Number)     ifTrue: [^self at: index truncated]     ifFalse: [self errorNonIntegerIndex]!
It is also free in the sense that the failure code is only invoked when the primitive fails and so adds nothing to the cost of successful accesses, which are the high dynamic frequency operation. Â It will also show up under profiling if one is concerned about efficiency, and so isn't a hidden cost.
It is also in keeping with Smalltalk's mixed mode/arbitrary precision implicit coercion number system that one *can* use fractions or floats as indices.
Stripping out coercions like this will make the system more brittle. Â So please do *not* remove this "hack". Â I think it's a feature and a useful one.
Can you give me an example that demonstrates the usefulness of this feature?
I think the right question is: - if we going to remove that, what alternative we're proposing? Like: throw a special exception class, so people may handle it and use rounding in case of need? And will it be more convenient to programmer? Less error prone?
Levente
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-- Best regards, Igor Stasenko AKA sig.
participants (6)
-
csrabak＠bol.com.br -
Eliot Miranda -
Igor Stasenko -
Levente Uzonyi -
Nicolas Cellier -
Stéphane Ducasse