Re: globals
Re: globals
- Subject: Re: globals
- From: "Mark J. Reed" <email@hidden>
- Date: Thu, 16 Sep 2010 11:18:22 -0400
On Thu, Sep 16, 2010 at 8:54 AM, tom wible <email@hidden> wrote:
> thanx to all for your replies:-) my problem is not that i don't know the
> difference between reference & value, it's that i don't know which way or
> when a/s does it
As far as I know, strings (text) and numbers are the only things that
aren't passed around by reference. Not everything passed around by
reference is necessarily mutable, however.
>...then there's the question of passing parameters: by
> value or reference...
Whatever the variable holds directly is what's passed to a function.
The variable itself is not passed by reference, so you can't change
what it holds, but if what it holds happens to *be* a reference to a
mutable item, you can change that item.
so this works:
to push(aList, anItem)
set end of aList to anItem - leaves aList alone, uses it to find
list and modify it
end
set A to {}
push(A,1)
A -- {1}
but this doesn't:
to push(aList, anItem)
set aList to aList & anItem - changes aList to point to a new
list, but only within body of handler
end
set A to {}
push(A, 1)
A -- {}
>
> shane wrote:
>>
>> For mutable classes like list, record and date...
>> ...
>> For immutable classes like text, real, etc, ...
>
> now that's the kind of info i'd like to see in a table, not scattered in
> archives somewhere;-}
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Mark J. Reed <email@hidden>
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| | >Re: globals (From: tom wible <email@hidden>) |