Re: [Newbies] Re: Recap: How to empty a collection
On Feb 20, 2008, at 2:01 , nicolas cellier wrote: One thing I wasn't clear on is whether Bert's suggestion: aColl removeAllSuchThat: [:anElement| true]. Is okay, and why it's okay while many of the other similar approaches were not. Bert's suggestion is simple and works well. The only question is about efficiency. Up to (Down to?) subclasses to optimize it. #removeAllSuchThat: is actually optimized in subclasses (look at its implementation in OrderedCollection). - Bert - ___ Beginners mailing list Beginners@lists.squeakfoundation.org http://lists.squeakfoundation.org/mailman/listinfo/beginners
Re: [Newbies] Re: Recap: How to empty a collection
Ok, I reimplemented this method as Bert suggested and in the next version of Aida/Web it will be: OrderedCollectionremoveAll remove all elements quickly self removeAllSuchThat: [:each | true]. Squeak specific self become: OrderedCollection new VW specific Note that this method is still an extension of Aida and it must therefore be portable among dialects, which is the reason of commented code for VW above. Best regards Janko Bert Freudenberg wrote: On Feb 20, 2008, at 2:01 , nicolas cellier wrote: One thing I wasn't clear on is whether Bert's suggestion: aColl removeAllSuchThat: [:anElement| true]. Is okay, and why it's okay while many of the other similar approaches were not. Bert's suggestion is simple and works well. The only question is about efficiency. Up to (Down to?) subclasses to optimize it. #removeAllSuchThat: is actually optimized in subclasses (look at its implementation in OrderedCollection). -- Janko Mivšek AIDA/Web Smalltalk Web Application Server http://www.aidaweb.si ___ Beginners mailing list Beginners@lists.squeakfoundation.org http://lists.squeakfoundation.org/mailman/listinfo/beginners
[Newbies] Re: Recap: How to empty a collection
Klaus D. Witzel a écrit : On Wed, 20 Feb 2008 02:01:49 +0100, nicolas cellier wrote: Some proposed an alternative based on (self removeAll: self), and started writing optimized versions of #removeAll:. No, (anOrderedCollection removeAll: anOrderedCollection) was not optimized. It had a *very* long known bug, which was fixed. Please do less mixing of subjects in threads. OK, I'm extrapolating. In this case, while you are at it: | aSet | aSet :='Klaus' asSet. aSet removeAll: aSet. aSet | aHeap | aHeap := Heap withAll: 'Witzel'. aHeap removeAll: aHeap. aHeap I would have used my name, but it seems i am removeable ;-) | aSet | aSet :='Cellier' asSet. aSet removeAll: aSet. aSet Try with the collection of your choice. In the mean time, don't use (self removeAll: self)... Yes i'm mixing threads,should be How to NOT empty a collection ;-) Nicolas I think our biggest problem is that we have plenty possible ways to do it... Finding a balance between genericity and efficiency... No, more correctness at the price of less efficiency :) Nicolas Agree on this one. Then allow removeAllSuchThat: as default implementation. Nicolas ___ Beginners mailing list Beginners@lists.squeakfoundation.org http://lists.squeakfoundation.org/mailman/listinfo/beginners
[Newbies] Re: Recap: How to empty a collection
On Wed, 20 Feb 2008 23:05:47 +0100, nicolas cellier wrote: Klaus D. Witzel a écrit : On Wed, 20 Feb 2008 02:01:49 +0100, nicolas cellier wrote: Some proposed an alternative based on (self removeAll: self), and started writing optimized versions of #removeAll:. No, (anOrderedCollection removeAll: anOrderedCollection) was not optimized. It had a *very* long known bug, which was fixed. Please do less mixing of subjects in threads. OK, I'm extrapolating. O.K. the fix from OrderedCollection *could* be applied to Set (the fix requires #copyEmpty), but see Heap below. In this case, while you are at it: | aSet | aSet :='Klaus' asSet. aSet removeAll: aSet. aSet | aHeap | aHeap := Heap withAll: 'Witzel'. aHeap removeAll: aHeap. aHeap Don't use Heap much, it is not very conformant; example: (Heap withAll: 'array') reject: [:x | x = $r] = an Array. Perhaps people didn't know about *all* senders of #species ... I would have used my name, but it seems i am removeable ;-) | aSet | aSet :='Cellier' asSet. aSet removeAll: aSet. aSet Try with the collection of your choice. In the mean time, don't use (self removeAll: self)... One step after the other :) no doubt #removeAll: gets fixed, perhaps in the next release? Yes i'm mixing threads,should be How to NOT empty a collection ;-) Nicolas I think our biggest problem is that we have plenty possible ways to do it... Finding a balance between genericity and efficiency... No, more correctness at the price of less efficiency :) Nicolas Agree on this one. Then allow removeAllSuchThat: as default implementation. Nicolas ___ Beginners mailing list Beginners@lists.squeakfoundation.org http://lists.squeakfoundation.org/mailman/listinfo/beginners
[Newbies] Re: Recap: How to empty a collection
On Tue, 19 Feb 2008 22:14:49 +0100, Blake wrote: I've been following this debate with some interest, but I think it's gone beyond a noob discussion. Is there a noob answer to this question? There ought to be. I'm sort of leaning toward: Q. How do you empty a collection. A. You don't, you replace it with a new instance. Q. What if you have references to the collection in multiple places? A. Wrap the collection in another class, and reference that. ?? Q. can I use #become: instead of wrapper? A. yes but the pro's don't like solutions with #become:, it smells /Klaus ___ Beginners mailing list Beginners@lists.squeakfoundation.org http://lists.squeakfoundation.org/mailman/listinfo/beginners
Re: [Newbies] Re: Recap: How to empty a collection
On Feb 19, 2008, at 10:36 PM, Klaus D. Witzel wrote: On Tue, 19 Feb 2008 22:14:49 +0100, Blake wrote: I've been following this debate with some interest, but I think it's gone beyond a noob discussion. Is there a noob answer to this question? There ought to be. I'm sort of leaning toward: Q. How do you empty a collection. A. You don't, you replace it with a new instance. Q. What if you have references to the collection in multiple places? A. Wrap the collection in another class, and reference that. ?? Q. can I use #become: instead of wrapper? A. yes but the pro's don't like solutions with #become:, it smells and it's slow in Squeak. /Klaus ___ Beginners mailing list Beginners@lists.squeakfoundation.org http://lists.squeakfoundation.org/mailman/listinfo/beginners Mth ___ Beginners mailing list Beginners@lists.squeakfoundation.org http://lists.squeakfoundation.org/mailman/listinfo/beginners
Re: [Newbies] Re: Recap: How to empty a collection
On Tue, 19 Feb 2008 14:20:51 -0800, Mathieu Suen [EMAIL PROTECTED] wrote: On Feb 19, 2008, at 10:36 PM, Klaus D. Witzel wrote: On Tue, 19 Feb 2008 22:14:49 +0100, Blake wrote: I've been following this debate with some interest, but I think it's gone beyond a noob discussion. Is there a noob answer to this question? There ought to be. I'm sort of leaning toward: Q. How do you empty a collection. A. You don't, you replace it with a new instance. Q. What if you have references to the collection in multiple places? A. Wrap the collection in another class, and reference that. ?? Q. can I use #become: instead of wrapper? A. yes but the pro's don't like solutions with #become:, it smells and it's slow in Squeak. Well, from what I was reading, slow and smells is putting it too mildly. It sounds like it can corrupt your image, i.e., leave you with non-working objects in unexpected places. I wouldn't even mention it. ___ Beginners mailing list Beginners@lists.squeakfoundation.org http://lists.squeakfoundation.org/mailman/listinfo/beginners
[Newbies] Re: Recap: How to empty a collection
Blake a écrit : Well, from what I was reading, slow and smells is putting it too mildly. It sounds like it can corrupt your image, i.e., leave you with non-working objects in unexpected places. I wouldn't even mention it. Huh? Have a proof of what you wrote? ___ Beginners mailing list Beginners@lists.squeakfoundation.org http://lists.squeakfoundation.org/mailman/listinfo/beginners
Re: [Newbies] Re: Recap: How to empty a collection
On Tue, 19 Feb 2008 15:08:56 -0800, nicolas cellier [EMAIL PROTECTED] wrote: Blake a écrit : Well, from what I was reading, slow and smells is putting it too mildly. It sounds like it can corrupt your image, i.e., leave you with non-working objects in unexpected places. I wouldn't even mention it. Huh? Have a proof of what you wrote? Proof? None at all. I just have this, by Gulik: [become:] doesn't work fine. It breaks code that relies on hashes; specifically, a Dictionary elsewhere in yo ur image can start acting screwy if you do a #become: variant that doesn't preserve an object's hash. See #becomeForwardcopyHash:. You would then also be relying on a Squeakish behaviour and your code would become less portable across Sm alltalk dialects. They are also a fantastic way to introduce bugs of various sorts, and can even cause an image to crash (as in, stack trace and exit to the OS). Say, for example, that one of the arguments you pass is accidently nil, true or false? Your image would c ontinue working... for a while. Does this sound like something a newbie should use? No, it does not. ===Blake=== ___ Beginners mailing list Beginners@lists.squeakfoundation.org http://lists.squeakfoundation.org/mailman/listinfo/beginners
Re: [Newbies] Re: Recap: How to empty a collection
On Tue, 19 Feb 2008 15:19:40 -0800, nicolas cellier [EMAIL PROTECTED] wrote: But become: is still essential for operations like growing the MethodDictionary when you add new methods to a class, or migrate allInstances when you a or remove an instance variable to a class, to name few. So, it is not bogus. Just handle with care. OK. Does a newbie need to use it? To empty a collection? (Or whatever?) I'm trying to get at what should be a very simple thing without going to the metal, as it were. One thing I wasn't clear on is whether Bert's suggestion: aColl removeAllSuchThat: [:anElement| true]. Is okay, and why it's okay while many of the other similar approaches were not. ___ Beginners mailing list Beginners@lists.squeakfoundation.org http://lists.squeakfoundation.org/mailman/listinfo/beginners
[Newbies] Re: Recap: How to empty a collection
Blake a écrit :
On Tue, 19 Feb 2008 15:08:56 -0800, nicolas cellier
[EMAIL PROTECTED] wrote:
Blake a écrit :
Well, from what I was reading, slow and smells is putting it too
mildly. It sounds like it can corrupt your image, i.e., leave you
with non-working objects in unexpected places. I wouldn't even
mention it.
Huh?
Have a proof of what you wrote?
Proof? None at all. I just have this, by Gulik:
[become:] doesn't work fine. It breaks code that relies on hashes;
specifically, a Dictionary elsewhere in yo ur image can start acting
screwy if you do a #become: variant that doesn't preserve an object's
hash. See #becomeForwardcopyHash:. You would then also be relying on a
Squeakish behaviour and your code would become less portable across Sm
alltalk dialects.
I see, become: does exchange #identityHash, and that makes our
IdentityDictionary work, god thanks, but there is no such provision for
ordinary #hash and Dictionary...
However, there are plenty of ordinary things that would have the same
result:
| key1 key2 dic |
key1 := 'abc' copy.
key2 := 'abd' copy.
dic := Dictionary new.
dic at: key1 put: 1.
dic at: key2 put: 2.
key1 at: 1 put: $z.
{dic includesKey: key1.
dic keys includes: key1.}
So i propose newbies do not use #at:put: considering the danger about
Dictionary not finding their keys...
That's too much.
becomeForward: is squeakish, but the thread was about Squeak
implementation of a core library...
A rule is to use becomeForward: only with a just created object as argument.
But right, that's just too much for this thread.
They are also a fantastic way to introduce bugs of various sorts, and
can even cause an image to crash (as in, stack trace and exit to the
OS). Say, for example, that one of the arguments you pass is accidently
nil, true or false? Your image would c ontinue working... for a while.
Does this sound like something a newbie should use? No, it does not.
===Blake===
OK, good lesson, thank you.
Handle with care.
Try finding better patterns.
Protect usage (don't use with an unknow argument).
It smells.
I agree.
But don't pretend it's broken please.
Anyway, why do you think all code is accessible in Smalltalk?
In the spirit, nothing is to be hidden from newbies eyes.
Yes I know, maybe some code should
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Re: [Newbies] Re: Recap: How to empty a collection
On Tue, 19 Feb 2008 15:59:57 -0800, nicolas cellier [EMAIL PROTECTED]
wrote:
However, there are plenty of ordinary things that would have the same
result:
| key1 key2 dic |
key1 := 'abc' copy.
key2 := 'abd' copy.
dic := Dictionary new.
dic at: key1 put: 1.
dic at: key2 put: 2.
key1 at: 1 put: $z.
{dic includesKey: key1.
dic keys includes: key1.}
So i propose newbies do not use #at:put: considering the danger about
Dictionary not finding their keys...
This seems pretty bad to me, too, but it seems more designed to break a
known weakness than to actually accomplish something. You know, like empty
a collection.s
But I'd probably argue that the above should work, and that it's a design
flaw that it doesn't.
Anyway, why do you think all code is accessible in Smalltalk?
In the spirit, nothing is to be hidden from newbies eyes.
Yes I know, maybe some code should
There's a positive fetish about this. I'm all for everything being
accessible. But everything being equally accessible all the time is not
pragmatic.
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[Newbies] Re: Recap: How to empty a collection
Blake a écrit :
On Tue, 19 Feb 2008 15:59:57 -0800, nicolas cellier
[EMAIL PROTECTED] wrote:
However, there are plenty of ordinary things that would have the same
result:
| key1 key2 dic |
key1 := 'abc' copy.
key2 := 'abd' copy.
dic := Dictionary new.
dic at: key1 put: 1.
dic at: key2 put: 2.
key1 at: 1 put: $z.
{dic includesKey: key1.
dic keys includes: key1.}
So i propose newbies do not use #at:put: considering the danger about
Dictionary not finding their keys...
This seems pretty bad to me, too, but it seems more designed to break a
known weakness than to actually accomplish something. You know, like
empty a collection.s
Yes, the example is dumb, but that's the kind of thing that happens in
real code (just split contructing/changing keys/accessing in three
different methods).
No use to forbid become: for this reason, there are better reasons (it's
slw), become: usage was sponsored once upon a time when it was fast,
providing both efficient and generic solutions.
But I'd probably argue that the above should work, and that it's a
design flaw that it doesn't.
Yes, but it is very hard to make it work efficiently.
So that's a limitation we must be aware of.
Anyway, why do you think all code is accessible in Smalltalk?
In the spirit, nothing is to be hidden from newbies eyes.
Yes I know, maybe some code should
There's a positive fetish about this. I'm all for everything being
accessible. But everything being equally accessible all the time is not
pragmatic.
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Re: [Newbies] Re: Recap: How to empty a collection
On Feb 20, 2008 2:17 PM, nicolas cellier [EMAIL PROTECTED] wrote: Blake a écrit : On Tue, 19 Feb 2008 15:59:57 -0800, nicolas cellier [EMAIL PROTECTED] wrote: snip Could we please move this discussion to squeak-dev please? We're going to scare the beginners. Gulik. -- http://people.squeakfoundation.org/person/mikevdg http://gulik.pbwiki.com/ ___ Beginners mailing list Beginners@lists.squeakfoundation.org http://lists.squeakfoundation.org/mailman/listinfo/beginners
[Newbies] Re: Recap: How to empty a collection
On Wed, 20 Feb 2008 02:01:49 +0100, nicolas cellier wrote: ... Bert's suggestion is simple and works well. The only question is about efficiency. Up to (Down to?) subclasses to optimize it. Some proposed an alternative based on (self removeAll: self), and started writing optimized versions of #removeAll:. No, (anOrderedCollection removeAll: anOrderedCollection) was not optimized. It had a *very* long known bug, which was fixed. Please do less mixing of subjects in threads. I think our biggest problem is that we have plenty possible ways to do it... Finding a balance between genericity and efficiency... No, more correctness at the price of less efficiency :) Nicolas ___ Beginners mailing list Beginners@lists.squeakfoundation.org http://lists.squeakfoundation.org/mailman/listinfo/beginners
