make list 0 versus make list 
[1/5] from: princepawn::lycos::com at: 27-Aug-2000 11:30
I read something in the REBOL McGraw-Hill book, but would like to verify it. Is there a difference on subsequent invocations of a function if I bind a (local?) value using make list! 0 versus make list!  So, now I have created 4 cases: make list!.....0 or  the word being defined...../local to function or global to rebol If I could get an answer to all four of these cases, I would be a much clearer on state retention between function invocations. Thanks. Terrence "Perl Refugee" Brannon
[2/5] from: al:bri:xtra at: 28-Aug-2000 15:20
Terrence "Perl Refugee" Brannon wrote:
> I read something in the REBOL McGraw-Hill book, but would like to verify
> Is there a difference on subsequent invocations of a function if I bind a
(local?) value using make list! 0 versus make list! 
> So, now I have created 4 cases: > > make list!.....0 or  > the word being defined...../local to function or global to rebol > > If I could get an answer to all four of these cases, I would be a much
clearer on state retention between function invocations. With this: make list! 999 the number 999 suggests to Rebol how much space to allocate to the list. With this: make list!  the "" suggests to Rebol that no minimum size of memory be allocated to the list!. In both cases, Rebol will expand or contract the list as required to hold the data in the list. If you want to make the word local to the function, then: MyListFunction: function  [MyList] [ MyList: make list! 999 ;... ] If you want to make the word global: MyListFunction: function   [ MyList: make list! 999 ;... ] In both of the above functions, the 'MyList word is allocated a new 'list! each time the function MyListFunction is invoked. If you want to keep the same list, each time the function is invoked, put: MyList: make list! 999 outside of MyListFunction. Better still, use a object!: MyList: make object! [ MyList: make list! 999 MyOperation: function   [ ;... ] ] Andrew Martin ICQ: 26227169 http://members.xoom.com/AndrewMartin/
[3/5] from: agem:crosswinds at: 28-Aug-2000 17:48
maybe Terrence read something about [a:  ] versus [ a: copy  ] versus [ a: make list!  ] ? in the last case the block is copied too, means you have allways an empty list. with [a: ] the block will remember its changes on subsequent invocations. --- [Al--Bri--xtra--co--nz] wrote on 28-Aug-2000/15:20:44+12:00
[4/5] from: galtbarber:mailandnews at: 28-Aug-2000 14:05
I am probably behind you all on this thread, but when I tried it I was surprised. Rebol may have always been this way and I just didn't notice before? Interesting!
>> make block! 0
>> make list! 0
== make list! 
>> mold make list! [stuff and more stuff]
== "make list! [stuff and more stuff]"
>> mold make block! [stuff and more stuff]
== "[stuff and more stuff]" So there is a fundamental difference between them? I had thought the list would behave like block itself. When I see the list reported like that it reminds me of make object! in the way that mold or probe return it. -Galt
[5/5] from: galtbarber:mailandnews at: 28-Aug-2000 14:36
> In both cases, Rebol will expand or contract the list as required to hold > the data in the list.
It is true that Rebol will expand memory for a block or list automatically, although you can help speed it up by pre-initializing to a large number of elements if you know they will be needed. In the case of a block, however, I think it does not release memory automatically. I think it holds onto the largest memory that instance of the block has used in case you need that space again. So, it is quite possible that the same thing applies to lists, as far as system storage usage goes. Obviously, if you really knew that you had used tons of memory and that you wouldn't need that again, you could create a copy of the original that would be no larger than needed. b: make block! 10000000 [... do some stuff, now it is just small, but non-empty...] b: make block! b now b will point to a new smaller block, I hope, and the big original should be garbage recycled. of course if that didn't work, this should work: b: copy b Anyway, I am not sure how to check the exact amount of ram used accurately. Recycle seems to help sometimes, but I can't always get the memory reported by taskmgr to show it's minimum value, so Rebol must be hanging onto some ram in case the user asks for more later. Can someone out there enlighten us? Thanks, -Galt p.s. for most of my programs, I don't bother to pre-initialize the size. I think that's not necessary unless you have a specific small bit of code that must be highly optimized for speed, which is usually not the case for my own programs.