Re: Interface without Inheritance
On Thursday, 21 February 2013 20:11:59 UTC+2, Rui Maciel wrote:
=D6=F6 Tiib wrote:
Certainly. Find a good book about templates and their usage and
study it. Rest assured, nothing of there is as simple to use as
virtual function.
Templates aren't the bogeyman you are making it out to be.
Bogeyman? No. Just more complex to use I said.
For example, can you come up with an example based on inheritance/virtual
functions which implements a policy pattern in a way which is simpler to
read and more concise than the following example?
Can you elaborate it bit more about what yours "policy pattern" is
(book/link)? I have so far had impression that it is synonym of
"strategy pattern" that I know well.
This was not certainly strategy pattern. You did not change strategy
(or policy) of some object dynamically run-time.
As for what it did achieve ... then it is easier with interface,
(IMHO but YMMV):
#include <iostream>
#include <string>
struct IOverView
{
virtual std::string name() = 0;
virtual std::string review() = 0;
virtual std::string ID() = 0;
};
void output( IOverView& t )
{
std::cout << "This is what people think of " << t.name() << "\n";
std::cout << "\t=AB" << t.review() << "=BB\n";
std::cout << "ID: " << t.ID() << std::endl;
}
struct ProductA
: public IOverView
{
virtual std::string name() override { return "A"; };
virtual std::string review() override { return "It's ok"; };
virtual std::string ID() override { return "asdf"; };
int bar() {return 1;};
};
struct ProductB
: public IOverView
{
virtual std::string name() override { return "B"; };
virtual std::string review() override { return "It's nice"; };
virtual std::string ID() override { return "fdsa"; };
void foo() {};
};
int main()
{
ProductA A; // diagnostics here if something from
ProductB B; // IOverView was not properly implemented
output( A );
output( B );
}