/*
CopyRight GPL 2004 mmc Mike Chirico mchirico@users.sourceforge.net
Created: Sun Apr 4 23:47:32 EDT 2004
This is an example of polymorphism. Take a look at print_list
BjS spells it like void print_list(const list<Vehicle*>&s )
but, here it's made to work with _vectors_, and _lists_. The
addition T, in the typename is not used here or needed.
But, it shows more flexibility. In otherwords, it will
for multiple _abstract classes_.
So, putting in print_list(const list<Vehicle*>&s ) works for
all derived classes from Vehicle...it prints out the correct
p_data()
The template <typename T, template <typename> class C> allows
for any derived class to be used. However, here, so for,
Vehicle is the only derived class.
So, it's polymorphism plus.
Ref:
http://cvs.sourceforge.net/viewcvs.py/cpearls/cpearls/src/development/class/derived
output:
passenger: 0
model: Caprice Classic
owner: Bob Anderson
year_made: 0
top_speed: 0
color: undefined
VIN: PKZ23483218
passenger: 0
model: Sun Fish
owner: Bob Anderson
year_made: 0
top_speed: 0
color: undefined
LICENSE: NYNCWW98
Type of boat: Sailboat
model: Lawn-Boy: DuraForce
owner: Bob Anderson
blade length: 21
Vector:
passenger: 0
model: Caprice Classic
owner: Bob Anderson
year_made: 0
top_speed: 0
color: undefined
VIN: PKZ23483218
passenger: 0
model: Sun Fish
owner: Bob Anderson
year_made: 0
top_speed: 0
color: undefined
LICENSE: NYNCWW98
Type of boat: Sailboat
model: Lawn-Boy: DuraForce
owner: Bob Anderson
blade length: 21
*/
#include <iostream>
#include <list>
#include <vector>
#include <string>
using namespace std;
class Vehicle {
protected:
int passenger;
string model;
string owner;
int year_made;
int top_speed;
string color;
public:
Vehicle(): passenger(0),model("undefined"),owner("undefined"), year_made(0), top_speed(0), color("undefined") {}
Vehicle(const string& model, const string& owner): passenger(0),model(model),owner(owner), year_made(0), top_speed(0), color("undefined") {}
virtual void p_data() = 0;
//virtual void set_year_made(const int year_made) { this->year_made=year_made; }
};
// Or, cleaner but less flexibility
// void print_list(const list<Vehicle*>& s)
// Note, below works with Vectors for New Abstract Types
template <typename T, template <typename> class C>
void print_list(const C<T*>& s)
{
for_each(s.begin(),s.end(),mem_fun(&Vehicle::p_data));
}
class Car : public Vehicle {
private:
string vin_num;
public:
Car() { }
Car(const string& model, const string& owner): Vehicle(model,owner) {}
Car(const string& model, const string& owner,const string& vin): Vehicle(model,owner),vin_num(vin) {}
void p_data() {
cout << endl;
cout << "passenger: " << passenger << endl;
cout << "model: " << model << endl;
cout << "owner: " << owner << endl;
cout << "year_made: " << year_made << endl;
cout << "top_speed: " << top_speed << endl;
cout << "color: " << color << endl;
cout << "VIN: " << vin_num << endl;
}
};
class Boat : public Vehicle {
private:
string tofb;
string lic;
public:
Boat() { }
Boat(const string& model, const string& owner): Vehicle(model,owner) {}
Boat(const string& model, const string& owner,const string& tofb,const string& lic):
Vehicle(model,owner),tofb(tofb),lic(lic) {}
void p_data() {
cout << endl;
cout << "passenger: " << passenger << endl;
cout << "model: " << model << endl;
cout << "owner: " << owner << endl;
cout << "year_made: " << year_made << endl;
cout << "top_speed: " << top_speed << endl;
cout << "color: " << color << endl;
cout << "LICENSE: " << lic << endl;
cout << "Type of boat: " << tofb << endl;
}
};
class Lawnmower : public Vehicle {
private:
int blade_len;
public:
Lawnmower() {}
Lawnmower(const string& model, const string& owner,int blade_len)
: Vehicle(model,owner) , blade_len(blade_len) {}
void p_data() {
cout << endl;
cout << "model: " << model << endl;
cout << "owner: " << owner << endl;
cout << "blade length: " << blade_len << endl;
}
};
int main(void)
{
Car c("Caprice Classic","Bob Anderson","PKZ23483218");
Boat b("Sun Fish","Bob Anderson","Sailboat","NYNCWW98");
Lawnmower lm("Lawn-Boy: DuraForce","Bob Anderson",21);
list<Vehicle*> vl;
vl.push_back(&c);
vl.push_back(&b);
vl.push_back(&lm);
print_list(vl);
vector<Vehicle*> vv;
vv.push_back(&c);
vv.push_back(&b);
vv.push_back(&lm);
cout << endl << "Vector: " << endl;
print_list(vv);
}
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Mike Chirico, a father of triplets (all girls) lives outside of
Philadelphia, PA, USA. He has worked with Linux since 1996, has a Masters
in Computer Science and Mathematics from Villanova University, and has
worked in computer-related jobs from Wall Street to the University of
Pennsylvania. His hero is Paul Erdos, a brilliant number theorist who was
known for his open collaboration with others.
Mike's notes page is souptonuts. For
open source consulting needs, please send an email to
mchirico@gmail.com. All consulting work must include a donation to
SourceForge.net.
