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| DATE | 2016-12-10 |
| FROM | Ruben Safir
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| SUBJECT | Subject: [Learn] const puzzle and literal type arguments
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From learn-bounces-at-nylxs.com Sat Dec 10 19:33:55 2016
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From: Ruben Safir
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Date: Sat, 10 Dec 2016 19:33:51 -0500
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Subject: [Learn] const puzzle and literal type arguments
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Section 12.2.1
Reference Arguments
317
BS
void f(const vector&);
void f(vector&&);
// (non-const) lvalue reference argument
// const lvalue reference argument
// rvalue reference argument
void g(vector& vi, const vector& cvi)
{
f(vi);
// call f(vector&)
f(vci);
// call f(const vector&)
f(vector{1,2,3,4}); // call f(vector&&);
}
We must assume that a function will modify an rvalue argument, leaving
it good only for de-
struction or reassignment (=C2=A717.5). The most obvious use of rvalue
references is to define move
constructors and move assignments (=C2=A73.3.2, =C2=A717.5.2). I=E2=80=99m =
sure someone
will find a clever use for
const-rvalue-reference arguments, but so far, I have not seen a genuine
use case.
Please note that for a template argument T, the template argument type
deduction rules give T&&
a significantly different meaning from X&& for a type X (=C2=A723.5.2.1). F=
or
template arguments, an
rvalue reference is most often used to implement =E2=80=98=E2=80=98perfect =
forwarding=E2=80=99=E2=80=99
(=C2=A723.5.2.1, =C2=A728.6.3).
-- =
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-- =
So many immigrant groups have swept through our town
that Brooklyn, like Atlantis, reaches mythological
proportions in the mind of the world - RI Safir 1998
http://www.mrbrklyn.com
DRM is THEFT - We are the STAKEHOLDERS - RI Safir 2002
http://www.nylxs.com - Leadership Development in Free Software
http://www2.mrbrklyn.com/resources - Unpublished Archive
http://www.coinhangout.com - coins!
http://www.brooklyn-living.com
Being so tracked is for FARM ANIMALS and and extermination camps,
but incompatible with living as a free human being. -RI Safir 2013
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