/* The following code example is taken from the book
* "C++ Templates - The Complete Guide"
* by David Vandevoorde and Nicolai M. Josuttis, Addison-Wesley, 2002
*
* (C) Copyright David Vandevoorde and Nicolai M. Josuttis 2002.
* Permission to copy, use, modify, sell and distribute this software
* is granted provided this copyright notice appears in all copies.
* This software is provided "as is" without express or implied
* warranty, and with no claim as to its suitability for any purpose.
*/
#include <iostream>
// PolicySelector<A,B,C,D> creates A,B,C,D as base classes
// - Discriminator<> allows having even the same base class more than once
template <typename Base, int D>
class Discriminator : public Base {
};
template <typename Setter1, typename Setter2,
typename Setter3, typename Setter4>
class PolicySelector : public Discriminator<Setter1,1>,
public Discriminator<Setter2,2>,
public Discriminator<Setter3,3>,
public Discriminator<Setter4,4> {
};
// default policies
class DefaultPolicy1 {};
class DefaultPolicy2 {};
class DefaultPolicy3 {
public:
static void doPrint() {
std::cout << "DefaultPolicy3::doPrint()\n";
}
};
class DefaultPolicy4 {};
// define default policies as P1, P2, P3, P4
class DefaultPolicies {
public:
typedef DefaultPolicy1 P1;
typedef DefaultPolicy2 P2;
typedef DefaultPolicy3 P3;
typedef DefaultPolicy4 P4;
};
// class to define a usage of the default policy values
// - avoids ambiguities if we derive from DefaultPolicies more than once
class DefaultPolicyArgs : virtual public DefaultPolicies {
};
// class templates to override the default policy values
template <typename Policy>
class Policy1_is : virtual public DefaultPolicies {
public:
typedef Policy P1; // overriding typedef
};
template <typename Policy>
class Policy2_is : virtual public DefaultPolicies {
public:
typedef Policy P2; // overriding typedef
};
template <typename Policy>
class Policy3_is : virtual public DefaultPolicies {
public:
typedef Policy P3; // overriding typedef
};
template <typename Policy>
class Policy4_is : virtual public DefaultPolicies {
public:
typedef Policy P4; // overriding typedef
};
// create class template with four policies and default values
template <typename PolicySetter1 = DefaultPolicyArgs,
typename PolicySetter2 = DefaultPolicyArgs,
typename PolicySetter3 = DefaultPolicyArgs,
typename PolicySetter4 = DefaultPolicyArgs>
class BreadSlicer {
typedef PolicySelector<PolicySetter1, PolicySetter2,
PolicySetter3, PolicySetter4>
Policies;
// use Policies::P1, Policies::P2, //... to refer to the various policies.
public:
void print () {
Policies::P3::doPrint();
}
//...
};
// define a custom policy
class CustomPolicy {
public:
static void doPrint() {
std::cout << "CustomPolicy::doPrint()\n";
}
};
int main()
{
BreadSlicer<> bc1;
bc1.print();
BreadSlicer<Policy3_is<CustomPolicy> > bc2;
bc2.print();
}
C++_Templates_The_Complete_Guide_book_code.zip
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C++_Templates_The_Complete_Guide_book_code.zip （254个子文件） 
namedtmpl.cpp 3KB types.cpp 2KB countingptrtest.cpp 2KB tracertest.cpp 2KB functorops.cpp 2KB staticpoly.cpp 2KB dynapoly.cpp 2KB stack6test.cpp 2KB stack8test.cpp 2KB funcwrap.cpp 2KB accum8.cpp 1KB stack7test.cpp 1KB compose5.cpp 1KB funcptr.cpp 1KB max3.cpp 1KB unruh.cpp 1KB tuple1.cpp 1KB max2.cpp 1KB stack5test.cpp 1KB compose4.cpp 1KB compose3.cpp 1KB isclasst.cpp 1KB stack4test.cpp 1KB elementtype.cpp 1KB stack3test.cpp 1KB max3a.cpp 1KB exprmain.cpp 1KB compose1.cpp 1KB compose2.cpp 1KB stack2test.cpp 1KB stack1test.cpp 1KB virtual.cpp 1KB functor1.cpp 1KB printmax.cpp 1KB accum6.cpp 1KB accum5.cpp 1KB accum9.cpp 1KB lazy.cpp 1KB accum3.cpp 1KB accum2.cpp 1KB accum4.cpp 1KB accum1.cpp 1KB max4.cpp 1KB rparam2.cpp 1KB duo5.cpp 1KB functordemo.cpp 1KB accum7.cpp 1001B addvaltest.cpp 1000B ebco1.cpp 976B adl.cpp 973B max.cpp 961B bindtest.cpp 954B ebco2.cpp 935B testcounter.cpp 935B max.cpp 907B sqrt2.cpp 905B sqrt1.cpp 905B refnonref.cpp 886B max5.cpp 868B sqrt4.cpp 866B sqrt3.cpp 866B type1test.cpp 865B compose6.cpp 860B rparam1.cpp 858B max6.cpp 851B truletest.cpp 845B holdertest.cpp 816B inject.cpp 814B loop2.cpp 808B loop1.cpp 804B sizeof.cpp 768B implicit.cpp 764B sarray2.cpp 759B nontmpl.cpp 756B myfirst3.cpp 751B fppm.cpp 736B apply1.cpp 736B apply2.cpp 736B myfirst.cpp 727B promote1.cpp 713B tracer.cpp 702B printcolltest.cpp 683B funcoverload.cpp 676B duo1.cpp 669B myfirst3main.cpp 666B myfirst2main.cpp 666B myfirst4main.cpp 666B myfirstmain.cpp 665B empty.cpp 661B pow3b.cpp 653B pow3.cpp 652B sarray1.cpp 649B myfirstinst.cpp 643B refmemtest.cpp 638B csm1.cpp 556B Makefile.h 3KB typet.hpp 8KB typet.hpp 8KB binder5.hpp 5KB countingptr.hpp 4KB共 254 条
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