🚀 go-pugleaf

In article <4eucnc$hr9@hermes.synopsys.com> jbuck@Synopsys.COM (Joe
Buck) writes:

|> "john (j.d.) hickin" <hickin@bnr.ca> writes:
|> >And this, the expectation that constructors of the form X(X&) and
|> >X(const X&) must perform a *copy* operation, is, IMHO, the trouble.

|> No, the notion that these constructors perform copy operations (and only
|> copy operations) is deeply wired in to the language, in at least three
|> places: argument passing, return value passing, and optimizing away of
|> copy constructors all assume these constructors mean "copy".

|> >The original term was reference constructor, a name which, in my opinion,
|> >carefully stepped around all subtleties of language.

|> I have never seen this term used.  Stroustrup said "copy constructor"
|> at a very early stage.

|> 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).

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.

--
James Kanze         Tel.: (+33) 88 14 49 00        email: kanze@gabi-soft.fr
GABI Software, Sarl., 8 rue des Francs-Bourgeois, F-67000 Strasbourg, France
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