Prototype and c++ conversion operator

[v4vijayakumar]

Can "c++ conversion operator" be considered as an example for
Prototype design pattern?

Following example explains, C++ conversion operator.

#include <iostream>
#include <string>
using namespace std;

class test
{
public:
operator string ()
{
return "test";
}
};

int main()
{
test t;
string s = t;

cout << s << endl;

return 0;
}

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cross posting to comp.object and comp.lang.c++

[Victor Bazarov]

v4vijayakumar wrote:

Can "c++ conversion operator" be considered as an example for
Prototype design pattern?

Following example explains, C++ conversion operator.

#include <iostream>
#include <string>
using namespace std;

class test
{
public:
operator string ()
{
return "test";
}
};

int main()
{
test t;
string s = t;

cout << s << endl;

return 0;
}

IMHO, no. The point of the Prototype patters is that there exists
an object [of the same type] that has some traits you want your new
object to inherit, so to speak, and some traits you want your new
object to have different. The main point is that the prototype is
of the same type as the object you need to produce.

Generally speaking, the prototype in your case here is not the 't',
but the temporary object its conversion function returns. So, to
some extend you can probably claim that the conversion function does
play the role of prototyping mechanism, but the implementation of
this pattern is not in the conversion function but in the fact that
you copy-construct your 's' string in 'main'.

Just my $0.02.

V
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