array initialization in initialization list.

Hi,
I can initialize an array of class with a specific class as,
class Test{
public:
Test(int){}
};
Test x[2] = {Test(3),Test(6)}; using array initialization list. (Note
Test do NOT have a default ctor).
Is it possible to do so in the class parameter initialization using
specific ctor?
like
class TestContainer{
private:
Test _x;
public:
TestContainer(int size) : _x(Test(size) {}
};
This works.
class TestContainer{
private:
Test _x[2];
public:
TestContainer(int size) : ??? {} //how to do it like array
initialization?
};
In actual case Test class is a specific kind of semi-fixed-size
container (not defined in STL! ) which needs a size parameter. The
class like TestContainer holds such Test class two instance (and only
two). I know that an alternative is to store Test _x1, Test _x2; and in
initialization list TestContainer(int size) : _x1(Test(size) ,
_x2(Test(size)){} , or in general case, using an STL vector with
reserve space 2. Or storing a pointer instead of the object itself.
But my question is, In object initializer list can a array
initialization be called? If yes, what is the syntax?
Thanks
abir

re: array initialization in initialization list.

toton wrote:No.

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re: array initialization in initialization list.

On 28 Sep 2006 03:50:03 -0700 in comp.lang.c++, "toton"
<abirbasak@gmail.comwrote,Should be
TestContainer(int size) : _x(size) {}

Pay no attention to whether or not it resembles array initialization
syntax at this point.

See also "[10.6] Should my constructors use "initialization lists"
or "assignment"?" in Marshall Cline's C++ FAQ. You can get the FAQ
at:
http://www.parashift.com/c++-faq-lite/

re: array initialization in initialization list.

toton wrote:You can't with arrays, but you can with std::vector (which you should
probably be using anyway,
http://www.parashift.com/c++-faq-lit...html#faq-34.1). For
instance:

#include <vector>
using namespace std;

template<typename T>
class Initializer
{
vector<Tv_;
public:
Initializer( const unsigned capacity=0 )
{
v_.reserve( capacity );
}

Initializer& Add( const T& t )
{
v_.push_back(t);
return *this;
}

operator vector<T>() const
{
return v_;
}
};

class Example
{
const vector<doublev_;
public:
Example( double d0, double d1, double d2 )
: v_( Initializer<double>( 3 )
.Add(d0)
.Add(d1)
.Add(d2) )
{}
// ...
};

Cheers! --M

re: array initialization in initialization list.

toton wrote:Annoyingly, IIRC, arrays are the one thing that cannot be initialised
in the initialiser list as you would like to.

Gavin Deane

re: array initialization in initialization list.

Gavin Deane wrote:No, structs are also that thing. Aggregates cannot be initialised
except with default values. There is a proposal on the table, IIRC,
that might change that.

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