On 05 Feb 2009, at 05:55, David Emerson wrote:
"Dynamic arrays are reference counted: assignment of one dynamic
array-type variable to another will let both variables point to the
same array. Contrary to ansistrings, an assignment to an element of
one
array will be reflected in the other: there is no copy-on-write."
This is fine, but what is strange is that calling setlength DOES
perform
copy-on-write!
var a, b : array of longint;
begin
setlength (a,2);
b := a;
setlength (a,5);
writeln (length(b)); // I get 2, not 5
end.
Why this inconsistency?
It's the way Delphi works. In fact, calling setlength is /the/ way to
make a dynamic array unique (afaik, the only alternative is calling
copy, but that's slower in case the array already was unique.
Jonas
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