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Top Forums Programming About uncopyable class (on book:Effective C++) Post 302738345 by vistastar on Saturday 1st of December 2012 05:20:13 AM
Old 12-01-2012
About uncopyable class (on book:Effective C++)

See the following code:
Code:
#include<iostream>
using namespace std;
class Uncopyable
{
protected:
    Uncopyable(){cout<<"hehe\n";}
    ~Uncopyable(){}
private:
    Uncopyable(const Uncopyable &rhs){cout<<"oooops\n";};
    Uncopyable& operator=(const Uncopyable &rhs);
};

class Dog : private Uncopyable
{
    string name;
    int value;
public:

    Dog(const string &s, const int &v):name(s), value(v){}
public:
    //Dog(const Dog &rhs){};             //here is the question!
};

int main()
{
    Dog a("a", 9);
    Dog b(a);
}

If I comment out that line, g++ will complaint "Uncopyable::Uncopyable(const Uncopyable&) is private". I think that mean the default copy ctor of derived class created by g++ called the base class' copy ctor.


If I make available of that line, every thing is ok. It out put
Code:
hehe
hehe

I think this mean the default copy ctor of derived class created by g++ called the base class' default ctor.
Am I right? If yes, why doesn't the default copy ctor derived class, in condition 2, call the base class' copy ctor? Why it behave so inconsistently?

thank you!

Last edited by vistastar; 12-01-2012 at 06:31 AM..
 

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FBB::repeat(3bobcat)					      repeated function calls					      FBB::repeat(3bobcat)

NAME
FBB::repeat - call a (member) function a fixed number of times SYNOPSIS
#include <bobcat/repeat> DESCRIPTION
The FBB::repeat function template allows a function or member function to be called a certain number of times. The functions or member functions may define arguments. Arguments to these functions are specified when repeat is called, and are perfectly forwarded by the repeat function template to the (member) function called by repeat. The first argument of the repeat function template defines the number of times the (member) function must be called. The FBB::repeat function template are defined inline, allowing the compiler to `optimize away' the repeat function call itself. NAMESPACE
FBB All constructors, members, operators and manipulators, mentioned in this man-page, are defined in the namespace FBB. INHERITS FROM
- REPEAT FUNCTION TEMPLATE
The repeat function template is declared as: template <typename Counter, typename First, typename ...Params> void repeat(Counter counter, First &&first, Params &&...params); In this declaration, o Counter represents the counter's type. Usually an int or size_t. When calling repeat counter must be initialized to the number of times repeat must call the (member) function (see below); o First represents the prototype of a function or the name of a class. name of a class. Likewise, first either is the address (name) of the function to be called or the name of an object of class type First. In the latter case the object may or may not be a const object. o ...Params represents the set of parameter types of arguments which must be perfectly forwarded to the called function. If first rep- resents a class type object, the first argument must be the address of a member function of the class First. EXAMPLES
#include <iostream> #include <iterator> #include <algorithm> #include "../repeat" using namespace std; using namespace FBB; class Object { public: void member(int argc, char **argv) const; void member2(size_t &rept, int argc, char **argv); }; void Object::member(int argc, char **argv) const { cout << "member called "; copy(argv, argv + argc, ostream_iterator<char const *>(cout, " ")); } void Object::member2(size_t &rept, int argc, char **argv) { cout << "member2 called, iteration " << rept++ << " "; copy(argv, argv + argc, ostream_iterator<char const *>(cout, " ")); } void fun() { cout << "Fun called "; } int main(int argc, char **argv) { Object object; cout << " " "*** The number of arguments determines the repeat-count *** "; cout << "Fun without arguments: "; repeat(argc, fun); cout << "Object receiving argc and argv: "; repeat(argc, object, &Object::member, argc, argv); cout << "Object receiving argc and argv, showing the iteration count: "; size_t count = 0; repeat(argc, object, &Object::member2, count, argc, argv); Object const obj; cout << "Const Object receiving argc and argv: "; repeat(argc, obj, &Object::member, argc, argv); } FILES
bobcat/repeat - defines the class interface SEE ALSO
bobcat(7) BUGS
Be careful when using overloaded functions, as the template argument resolution mechanism may be unable to determine which function to call. If overloaded functions must be used, a static_cast is likely required to disambiguate your intentions. DISTRIBUTION FILES
o bobcat_3.01.00-x.dsc: detached signature; o bobcat_3.01.00-x.tar.gz: source archive; o bobcat_3.01.00-x_i386.changes: change log; o libbobcat1_3.01.00-x_*.deb: debian package holding the libraries; o libbobcat1-dev_3.01.00-x_*.deb: debian package holding the libraries, headers and manual pages; o http://sourceforge.net/projects/bobcat: public archive location; BOBCAT
Bobcat is an acronym of `Brokken's Own Base Classes And Templates'. COPYRIGHT
This is free software, distributed under the terms of the GNU General Public License (GPL). AUTHOR
Frank B. Brokken (f.b.brokken@rug.nl). libbobcat1-dev_3.01.00-x.tar.gz 2005-2012 FBB::repeat(3bobcat)
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