Re: What is the name of this pattern?
On Jul 22, 11:07 pm, Mike Reed <mike.ree...@googlemail.com> wrote:
Hi,
I'm just documenting some of my code and I cannot remember the name of
a pattern I have used. It allows a class to hold a collection of
objects of undefined types as long as they provide the correct
interface, and performs actions on those objects. However, the code
that performs the actions is template free and hence can be in a
separately compilable implementation file. Here is the code in the
simplest form I could get it:
#include <iostream>
#include <list>
class Processor
{
public:
void process()
{
for(Clients::iterator i = clients_.begin(); i != clients_.end
(); ++i)
(*i)->foo();
}
template <class T>
void addClient(T& t)
{
clients_.push_back(new ClientHolder<T>(t));
}
private:
struct ClientBase
{
// The interface clients must provide
virtual void foo() = 0;
};
template <class T>
struct ClientHolder : public ClientBase
{
ClientHolder(T& t) : t_(t) {}
void foo()
{
t_.foo();
}
T& t_;
};
typedef std::list<ClientBase*> Clients;
Clients clients_;
};
struct X {void foo() { std::cout << "X\n"; }};
struct Y {void foo() { std::cout << "Y\n"; }};
struct Z {void foo() { std::cout << "Z\n"; }};
int
main()
{
Processor p;
X x;
Y y;
Z z;
p.addClient(x);
p.addClient(y);
p.addClient(z);
p.process();
return 0;
}
Note the Processor::process() is not templated and so can go in a
separate implementation file. I can't remember where in my memory I
got this pattern from. Does it have a name?
Thanks,
Mike.
I'm not able to figure out the exact name of this pattern neither I've
ever seen any kind of such pattern available in any design pattern
book.
In your code using the help of ClientBase and template<T> ClientHolder
class you have designed a generic class which can store any type of
other object. In java there is such object named Object and in BOOST
there is such class boost::any. And finally using this type of class
you have created a list.
I don't think this should be given any name rather than a technique
how to store any kind of object into container.
If somebody can find out the name of this code ... Let's see.
--
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