Re: List Question: Can someone explain this to me?
Re: List Question: Can someone explain this to me?
- Subject: Re: List Question: Can someone explain this to me?
- From: Helmut Fuchs <email@hidden>
- Date: Fri, 14 Jun 2002 13:26:22 +0200
At 11:37 Uhr +0100 14.06.2002, Charles Arthur wrote:
No, I think the ASLG is glossing over the fact that it's cheap to fill
registers with data such as a number or text, but expensive to set up the
pointers required to follow a list (or record, or script object) around
memory. It's an assembler-level question.
Well, I guess it's not. Though you're right about the (speed and
especially _memory_) efficiency issue, I still tend to believe it's
got more to do with what is normally done with lists, records and
scripts as opposed to strings and numbers and such.
Lists, records (and scripts) are normally accessed and modified not
as a whole, but in small chunks - so it's quite sensible to make
using them by reference the default instead of the exception.
In another Apple grown language, i.e. NewtonScript, objects were
divided into two classes: mutable and immutable - mutable object
classes _always_ being references and immutable object classes
_always_ being copied - and the Documentation made sure everybody got
this point of distinction, whereas ASLG doesn't draw this line so
clearly. At least not that obviously.
And if you're wondering about AppleScript's behaviour: in PostScript
even substrings are handled by reference... fun debugging if you're
stumbling over such a thing for the first time...
-Helmut
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