[Newbies] How to empty a collection?

[Ron Teitelbaum]

Hi Cédrick, 

I believe there is too little agreement to do very much.  The suggestion you
presented as Bert's suggestion was actually mine.  So given the discussion
that followed I think I would actually follow Bert's advice.

aColl removeAllSuchThat: [:anElement| true].

But I suppose that is still following my own advice because

removeAllSuchThat: aBlock 
	"Evaluate aBlock for each element and remove all that elements from
	the receiver for that aBlock evaluates to true.  Use a copy to
enumerate 
	collections whose order changes when an element is removed (i.e.
Sets)."

	self copy do: [:each | (aBlock value: each) ifTrue: [self remove:
each]]

:) 

Ron Teitelbaum

> -----Original Message-----
> From: cdrick [mailto:cdrick65 at gmail.com]> 
> >
> > aCollection copy do: [:anElement |
> >         aCollection remove: anElement
> > ].
> >
> > Why copy?  If you start removing items from the collection, increasing
> the
> > index will cause you to skip elements.
> 
> I forgot that in my first attemp (and I knew that !)...
> 
> col := #(1 2 3) asOrderedCollection.
> col  removeAll: col.
> ^col   returns an OrderedCollection(2)
> 
> col  removeAll: col copy is ok.
> 
> So, following Bert suggestion, would it be possible to change removeAll:
> from...
> 
> removeAll: aCollection
> 	aCollection do: [:each | self remove: each].
> 	^ aCollection
> to
> 
> removeAll: aCollection
> 	aCollection copy do: [:each | self remove: each].
> 	^ aCollection
> or
> 
> removeAll: aCollection
> 	aCollection == self
> 		ifTrue: [aCollection copy do: [:each | self remove: each]]
> 		ifFalse: [aCollection do: [:each | self remove: each]].
> 	^ aCollection
> 
> or again
> removeAll: aCollection
> 	aCollection == self
>                 ifTrue: [self removeAll: aCollection copy]
>                 ifFalse: [aCollection do: [:each | self remove: each]].
> 
> Or maybe, if aCollection == self, a warning could be raised ?
> 
> What do you think ?
> 
> Cédrick