Stef:

But......
I use it all the time. It's a neat idea. Here is code I found by searching  all source for #{.

EToyIncommingMessages class>>allTypes

	^MessageTypes ifNil: [
		MessageTypes _ {
			self typeKeyboardChat.
			self typeMorph.
			self typeFridge.
			self typeStatusRequest.
			self typeStatusReply.
			self typeSeeDesktop.
			self typeAudioChat.
			self typeAudioChatContinuous.
			self typeMultiChat. } ]

HeadMorph>>addSpikyHair
	| hair |
	hair _ PolygonMorph
		vertices: {83 at 3. 81 at 30. 91 at 27. 111 at 23. 97 at 32. 112 at 37. 99 at 45. 114 at 52. 95 at 53. 55 at 43. 10 at 50. 1 at 40. 14 at 40. 8 at 26. 24 at 37. 15 at 11. 29 at 29. 30 at 16. 36 at 30. 41 at 6. 49 at 31. 54 at 8. 61 at 32. 64 at 1. 70 at 27}


Next is a fragment of a demo. The names Babble, Donut and Marble are humorous, but descriptive.

	d := BabbleDonutMorph new largeDonut; name: '- Commons Area -'.
	d addAllMarbles: {
		(BabbleMarbleMorph new mediumMarble name: 'Wendy').
		(BabbleMarbleMorph new mediumMarble name: 'Dave and Archie at home').
		(BabbleMarbleMorph new mediumMarble name: 'Tom in Minneapolis').
		(BabbleMarbleMorph new mediumMarble name: 'Mark').
		(BabbleMarbleMorph new mediumMarble name: 'Big Screen').
		(BabbleMarbleMorph new mediumMarble name: 'John in the Lab') } shuffled.


These are just a few examples I picked to show 'interesting' uses of { and }. I found 794 methods in my image that contained at least one ${. A few were commented out C code. Most were from the array constructor. It's used widely and the result of using it makes the code much more readable than 'Array with:'.

The construct is useful and widely used. If it has definitional and theoretical problems, then certainly look at how to fix those; but let's not discard a useful construct.


At 8:49 +0200 9/30/01, ducasse stephane wrote:
>Hi daniel
>
>I send it into the mailing list too becuase this is important
>
>From a language design perspective
>
>#() is necessary because it is compiled statically and cannot not be
>simulated by other construct. Storing #() in Stack frame is not really goo
>but this is an implementation aspect.

I don't think this is true at all.  #() holds symbols, strings, characters numbers, and in some Smalltalk systems it holds true and false. There is nothing in a #() that you can't write as a literal elsewhere, so:

   #( abc 'abc' 4  3.4  $r )

can be written as:

   (Array with: #abc with: 'abc'), (Array with: 4 with: 3.4 with: $r)

#() is a great convenience, but it is not absolutely necessary.

>#{} is not necessary because this is shortcut macro-expansion for Array new
>add: ....
>
>So why having only this one. There is two ways:
>    or you have a way to describe macro-expansion like in Scheme where you
>    can define any macro in a clear way (you know the semantic of the stuff
>
>    or we remove it because why not having
>        {{}} for Set new add:

This already has a definition: an empty array in an array, like:  #(#()).

>        {#[]} for OrderedCollection new....Because I use more
>                OrderedCollection than array

#[] isn't used in Squeak, but some Smalltalk systems (and maybe the standard) use it as a way of writing ByteArray literals:  #[ 0 255 76 98 4 67 2 ]. We should carefully decide if we want to differ from others in syntax. (Actually, 'we' already have; for some odd reason '#[' is a symbol!  I would have expected to have to write #'[' to get a symbol with a special character.)

I use more OrderedCollection's too, but it was interesting to note that after looking at a couple of hundred uses of {} I don't recall seeing even one message send to convert the array to something else. I think that OCs are widely used when code is building an indexed collection, but rare when the collection is built ahead of time by a literal array or array constructor.

>... SNIP ...
>

Dave
-- 
_______________________________
David N. Smith
IBM T J Watson Research Center
Hawthorne, NY
dnsmith at watson.ibm.com