Re: [boost] [cpo-proposal] presentation of the idea

On 08/12/13 19:07, Santiago Tapia wrote:

Hi everyone,

I would like to make a proposal for a new library. I only have a draft without documentation but I would like to know people’s opinion about the idea before making a formal proposal.

The library will be named CPO (containers for polymorphic objects) and it will provide containers to store dynamic allocated objects from a class hierarchy. I have drafted one container and I have two more in process. The cpo library could be an alternative solution for boost pointer container library or some other solutions that use pointers. In order to understand the idea, I think that the following example of the use of the library might be better than a long explanation:

#include #include <iostream>

using namespace boost::cpo;

class base { public: virtual int do_something(int a) const = 0; };

class derived_A : public base { public: derived_A(int b) : data(b) {} virtual int do_something(int a) const { return a + data; } protected: int data; };

class derived_B : public base { public: derived_B(int b) : data(b) {} virtual int do_something(int a) const { return a - data; } protected: int data; };

int main(int argc, char** argv) { classifier collection;

collection.insert( derived_A(21) ); collection.insert( derived_B(40) );

classifier::iterator i, e = collection.end();

for ( i = collection.begin(); i != e; ++i ) { const base& x = *i; std::cout << x.do_something(6) << std::endl; }

return 0; } [snip] Hi Santiago,

What if the class hierarchy is used to model a graph that contains cycles. For example, something like a spirit grammar where a non-terminal on the rhs of a non-terminals definition? Wouldn't this require some sort of smart pointer or other garbage collection method with the ability to collect cycles? -regards, Larry