Template object without object name

[babu198649]

hi
The below code compiles

typedef Correlation<vsip::Vector,support_full,value_type> cor;
Domain<1> aa(nrange);
cor co(aa,aa);

But if i modify the same code like below i get error

typedef Correlation<vsip::Vector,support_full,value_type> cor;
cor co(Domain<1>(nrange),Domain<1>(nrange));

why the object is not created with out the object name.
The error is

../ds.cpp:86: error: conversion from `vsip::Vector<std::complex<float>, vsip::Dense<1u, std::complex<float>, vsip::tuple<0u, 1u, 2u>, vsip::Local_map> >' to non-scalar type `vsip::Domain<1u>' requested
../ds.cpp:127:5: warning: no newline at end of file
make: *** [ds.o] Error 1

[CornedBee]

Again the function thing. I don't know why the compiler gives you this particular error, but "co" is once again a function returning a "cor" and taking two arguments of type "Domain<1>". You may get problems since the arguments have the same name.

Also, would you please just add the final newline to the file to silence this compiler warning?

[babu198649]

Thanks for reply
i for got to tell u that nrange is defined as

long unsigned int nrange = 4;

Even if nrange is an unsigned int object, does the compiler sees co as a function.

Also with the same compiler in the below code ,the object of Convolution is created.The second argument to the constructor is an object(which is created with out object name).

typedef Convolution<vsip::Vector,nonsym,support_full,value_type> con;
con c(replica, Domain<1>(nrange));

I am not sure whether an object can be created without object name.
The following example is taken from the text book which creates object without using object name

#include <iostream>
using namespace std;

template<class T, class U> class C
{
public:
	void f()
	{
		cout << "Primary Template\n";
	}
};

int main()
{
	C<float, int>().f(); 
}

In the above examle does the statement

C<float, int>().f();

creates a object and then calls the function f() or does somthing else.
Please confirm wheather a object can be created without using the object name.

[CornedBee]

Even if nrange is an unsigned int object, does the compiler sees co as a function.

The compiler doesn't care about the current meaning of nrange.

Also with the same compiler in the below code ,the object of Convolution is created.

Yes. Since replica isn't a type, the line can't be a function declaration, so it must be an object creation.

I am not sure whether an object can be created without object name.

It can be. The object is temporary, though - it is destroyed at the end of the statement.

[babu198649]

Thank u
If a constructor takes a pointer as an argument then new operator can be passed as the argument( new ClassName ) to create a object with out creating object name.

In the same way if a constructor takes an object by value or reference as an argument, is there a way to create a object without creating object name.

[CornedBee]

By value or by const reference. Mutable references cannot bind to temporaries. (Except as an extension in VC++.)

By the way, please drop the netspeak.

[babu198649]

Please post a simple working code,i tried to do it but i am unable to make work

[CornedBee]

Working code for what?

[babu198649]

By value or by const reference.

i am unable to make it work by value or by const reference.

Mutable references cannot bind to temporaries. (Except as an extension in VC++.)

As i know mutable variables can be altered by const functions,Is this what Mutable in the above statement mean or something else(I am not VC++ programmer).

[CornedBee]

void foo1(std::string); // by value
void foo2(std::string &); // by mutable reference
void foo3(const std::string &); // by const reference

int main()
{
  foo1(std::string("hey")); // Valid, temporary for by-value
  foo2(std::string("error")); // Invalid, temporary for mutable reference
  foo3(std::string("there")); // Valid, temporary by const reference
}