On Mar 20, 2006, at 9:01 PM, Mark Smith wrote:
I think the point is that when a variable is passed to a function/
handler 'normally', the data in it is duplicated, and if the data
is big, this is not as efficient as passing it by reference -
obviously, if you need to change the data in the called function/
handler, this may have unwanted side-effects, in which case
passing it normally is going to be better.
The problem you raise here is handled in more traditional languages
by declaring the reference to be constant. It strikes me that it
would not be a big change to expand the use of the "constant"
keyword. Then in situations such as Sarah was talking about the
handler/function would be declared as not changing the referred to
variable, something like
on myHandler constant @pByReferenceParameter
-- following then should cause compiler error
add 1 to @pByReferenceParameter
end myHandler
There is, of course, another use for references besides the
efficiency of not having to copy large data structures: returning
more than one value. This use doesn't suffer from the concern Sarah
raises about having external effects as, when used this way, the
parameter passed in should be empty. There isn't, of course, any
guarantee of this other than the caller being careful and writer of
the called function being careful to document that the parameter is
used for output only.
Spence
James P. Spencer
Rochester, MN
[EMAIL PROTECTED]
"Badges?? We don't need no stinkin badges!"
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