[jawsscripts] Re: Resizing arrays
- From: "Travis Roth" <travis@xxxxxxxxxxxxxx>
- To: <jawsscripts@xxxxxxxxxxxxx>
- Date: Thu, 5 Jan 2012 14:46:27 -0600
C comes to mind.
Not sure what you mean by "this sort". But I'd not put much past JAWS script
either way. <smile>
-----Original Message-----
From: jawsscripts-bounce@xxxxxxxxxxxxx
[mailto:jawsscripts-bounce@xxxxxxxxxxxxx] On Behalf Of Soronel Haetir
Sent: Thursday, January 05, 2012 2:35 PM
To: jawsscripts@xxxxxxxxxxxxx
Subject: [jawsscripts] Re: Resizing arrays
Yes, jaws script objects are referenced counted, it's the same process that
occurs if the variable were to simply go out of scope. I don't know that I've
ever seen a language of this sort that requires manual memory cleanup. I
suppose such might exist, but it would be very much the exception.
On 1/5/12, Travis Roth <travis@xxxxxxxxxxxxxx> wrote:
> Yes I thought the array copy was by reference as well.
>
> I have the same problem of not knowing array size in advance.
> But it does look useful that you can just make a new array on the
> existing variable, I hadn't realized that was possible. Does the old
> array just stop existing when new is called again? We've lost access
> to it but I am just wondering if JAWS does any garbage collection. I
> am thinking in the case of the default scripts, where those global
> variables are in existence until JAWS is unloaded, if garbage
> collection does not automatically occur using new repeatedly would start to
> be a memory leak.
>
> Like the ideas... Thanks everyone.
>
> -----Original Message-----
> From: jawsscripts-bounce@xxxxxxxxxxxxx
> [mailto:jawsscripts-bounce@xxxxxxxxxxxxx] On Behalf Of Doug Lee
> Sent: Thursday, January 05, 2012 1:55 PM
> To: jawsscripts@xxxxxxxxxxxxx
> Subject: [jawsscripts] Re: Resizing arrays
>
> A couple clarifications:
>
> First, to me at least, a "deep copy" is a full duplication of
> something with all subparts. My understanding of "s2 = s1" where they
> are arrays is that, in JAWS, only the pointer is copied. It still
> works for your usage though, so this is mostly just behind-the-scenes stuff
> for this case.
>
> Second though, your code assumes array sizes, and most of my cases
> don't have a clue in advance what size to use. As an example, consider
> code that creates a structure of information for each entry in a chat
> window. If the process of counting entries is as expensive as that for
> actually retrieving them, there's no reasonable way to know in advance
> how big to make the array. A collection becomes more efficient in this
> case, because it is dynamic while still being amenable to random access.
>
> On Thu, Jan 05, 2012 at 03:59:00PM -0300, Andrew Hart wrote:
> I don't understand your need for collections in order to use arrays
> globally. You just create the array at the size you need. If you
> need to add to it, you just fob it off to a local variable, assign a
> new larger array to the global var and then copy the array elements in
> the local var to the global one. Then, to finish, you erase the copy
> of the array by assigning it an unassigned array var of the same type,
> much as you would do with Object vars.
>
> For example:
>
> Var
> StringArray s1,
> StringArray S2,
> StringArray NULLStringArray
> s1 = New StringArray[5]
> ; fill the array with stuff
> ...
> ;Copy the array (this is a deep copy, not a shallow copy that only
> ;passes a reference pointer)
> s2 = s1
> s1 = New StringArray[10] ; make the array bigger ; Now copy the
> contents of
> s2 to s1 For i = 1 To 5
> s1[i] = s2[i]
> EndFor
> ; erase the array.
> ; Since JAWS performs deep array copies, it should reduce s2 to its
> ;minimal memory footprint, allowing the space to be reclaimed by the
> ;heap when appropriate conditions prevail
> s2 = NULLStringArray
>
>
> If you're serious about regularly resizing arrays, I'd recommend
> making a few functions using the relevant bits of the above example
> for resizing arrays of different types. You'd pass the array being
> resized by reference (using ByRef in the function declaration). Also,
> as this is a linear time operation, doing it a lot could slow things
> down if you are dealing with big arrays. Tricks for dealing with that
> are to always make the array bigger than what you need. For example,
> you could always double the size of the array whenever you run out of
> space and then resize it to conserve memory by removing unused
> portions later if it is not likely to be added to for a while.
>
> Hth,
> Andrew.
>
> On 5/01/2012 2:32 PM, Travis Roth wrote:
>> Perhaps a combination of a collection and an array would work then?
>> The documentation states that a collection can hold arrays. So when a
>> new array is wanted, delete the old one in the collection and make a
>> new
> one.
>>
>> I am not sure what type of performance that'd give, but might be
>> another workaround.
>>
>> The reason for not just creating new arrays is I need them to be
>> global, and there'd be no way to keep track of the names, or at least
>> not a practical way.
>> Bbut a collection may solve that.
>>
>> -----Original Message-----
>> From: jawsscripts-bounce@xxxxxxxxxxxxx
>> [mailto:jawsscripts-bounce@xxxxxxxxxxxxx] On Behalf Of Doug Lee
>> Sent: Thursday, January 05, 2012 11:26 AM
>> To: jawsscripts@xxxxxxxxxxxxx
>> Subject: [jawsscripts] Re: Resizing arrays
>>
>> JAWS 12 introduced a CollectionRemoveItem function for that.
>>
>> On Thu, Jan 05, 2012 at 11:23:32AM -0600, Travis Roth wrote:
>> Kind of messy but I see your reasoning.
>> How do you remove an item from a collection?
>>
>>
>> -----Original Message-----
>> From: jawsscripts-bounce@xxxxxxxxxxxxx
>> [mailto:jawsscripts-bounce@xxxxxxxxxxxxx] On Behalf Of Doug Lee
>> Sent: Thursday, January 05, 2012 10:21 AM
>> To: jawsscripts@xxxxxxxxxxxxx
>> Subject: [jawsscripts] Re: Resizing arrays
>>
>> In the absence of knowledge of a way to do that, I've been using
>> collections as dynamic arrays, where the keys are things like
>> intToString(i). You do need to stringify the keys though. When I do
>> that, I also sometimes include a count key that I keep updated when
>> adding or removing elements. This also allows for efficient sparse
>> arrays but does complicate their management a bit and precludes
>> things like inserts/deletes where elements slide in to fill the hole
>> or make
> room.
>>
>> On Thu, Jan 05, 2012 at 10:17:13AM -0600, Travis Roth wrote:
>> Is it possible to resize arrays in JAWS script?
>> It appears that the arrays are dynamically sized at runtime because
>> the new keyword is used.
>> But the documentation on the website does not seem to discuss
>> destroying or resizing arrays?
>> This may not be an issue for local variables, but I am thinking for a
>> global array where at some point it may be desireable to store
>> something larger than was originally set for.
>>
>>
>>
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