🚀 go-pugleaf

I wrote:
>|> Anyone who writes a class in which X(X&) or X(const X&) does not have the
>|> semantics of a copy operation is doing something wrong (e.g. auto_ptr in
>|> the draft standard is broken).

James Kanze US/ESC 60/3/141 #40763 <kanze@lts.sel.alcatel.de> writes:
>I wouldn't go quite that far.  X(X&) is a particular form of copy,
>which modifies the copied object.  If it is programmed in such a way
>that the number of intermittent copies is meaningless (as is the case
>in auto_ptr), then it is perfectly valid.

You're not really disagreeing with me, James.  X(X&) is a reasonable
thing to do in some cases, and the source object will then be modified,
but if this operation does not look like a copy that leaves the
functioning of the argument object mostly unaltered, the user of the class
is going to have problems and surprises.  Many uses of X(X&) just modify
private members to keep some sort of internal record, e.g. how many copies
there are and connections between them.


-- 
-- Joe Buck 	<jbuck@synopsys.com>	(not speaking for Synopsys, Inc)

Work for something because it is good,
not just because it stands a chance to succeed.	   -- Vaclav Havel
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