Created
February 18, 2011 05:47
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#include <stdio.h> | |
class Base { | |
public: | |
Base () { } | |
virtual ~Base () { } | |
}; | |
class Enroll : public virtual Base { | |
public: | |
virtual ~Enroll () { } | |
virtual void enroll () = 0; | |
}; | |
class Verify : public virtual Base { | |
public: | |
virtual ~Verify () { } | |
virtual void verify () = 0; | |
}; | |
class Both : public Enroll, public Verify { | |
public: | |
virtual ~Both () { } | |
virtual void enroll () { printf ("Enrolling.\n"); } | |
virtual void verify () { printf ("Verifying.\n"); } | |
}; | |
typedef Enroll* (*EnrollGenerator) (); | |
typedef Verify* (*VerifyGenerator) (); | |
Both* createInstanceOfBoth () { | |
return new Both(); | |
} | |
Enroll* createInstanceOfEnroll () { | |
return new Both(); | |
} | |
Verify* createInstanceOfVerify () { | |
return new Both(); | |
} | |
class Registry { | |
public: | |
Registry () { } | |
void setupBrokenGenerators () { | |
enrollGenerator = (EnrollGenerator)&createInstanceOfBoth; | |
verifyGenerator = (VerifyGenerator)&createInstanceOfBoth; | |
} | |
void setupWorkingGenerators () { | |
enrollGenerator = &createInstanceOfEnroll; | |
verifyGenerator = &createInstanceOfVerify; | |
} | |
Enroll* getEnroll () { return enrollGenerator (); } | |
Verify* getVerify () { return verifyGenerator (); } | |
EnrollGenerator enrollGenerator; | |
VerifyGenerator verifyGenerator; | |
}; | |
int main () { | |
Registry registry; | |
Enroll *enroller; | |
Verify *verifier; | |
printf ("Broken:\n"); | |
registry.setupBrokenGenerators (); | |
enroller = registry.getEnroll (); | |
verifier = registry.getVerify (); | |
enroller->enroll (); | |
verifier->verify (); | |
printf ("Working:\n"); | |
registry.setupWorkingGenerators (); | |
enroller = registry.getEnroll (); | |
verifier = registry.getVerify (); | |
enroller->enroll (); | |
verifier->verify (); | |
} |
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