Re: Improving ugly(?) design: Data validation

On 21 Jun, 21:51, Rune Allnor <all...@tele.ntnu.no> wrote:


Bah! Lots of bad stuff going on in the code I posted yesterday.
Below is a cleaned-up version. So much for coding on Saturday
afternoon...

Rune

/////////////////////////////////////////////////////////
#include <iostream>
#include <memory>

class EbClass; // Error base class
class E1Class; // Error type 1 class
class E2Class; // Error type 2 class

class HandlerClass{
public:
    virtual bool handleReport(std::auto_ptr<EbClass>);
    virtual void handleReport(E1Class*);
    virtual void handleReport(E2Class*);
};

class EbClass{
public:
    virtual void setHandler(HandlerClass*) = 0;
};

class E1Class : public EbClass {
public:
    virtual void setHandler(HandlerClass*);
};

class E2Class : public EbClass {
public:
    virtual void setHandler(HandlerClass*);
};

class ValidatorClass{
private:
    HandlerClass* handler_;
    std::auto_ptr<EbClass> error1(int) const;
    std::auto_ptr<EbClass> error2(int) const;

public:
    ValidatorClass(HandlerClass* h):handler_(h){};
    bool operator()(const int) const;
};

std::auto_ptr<EbClass> ValidatorClass::error1(int i) const
{
    // Check #1 fails is i == 1
    if (i==1) return std::auto_ptr<EbClass>(new E1Class());
    return std::auto_ptr<EbClass>();
}

std::auto_ptr<EbClass> ValidatorClass::error2(int i) const
{
    // Check #2 fails is i == 2
    if (i==2) return std::auto_ptr<EbClass>(new E2Class());
    return std::auto_ptr<EbClass>();
}

bool ValidatorClass::operator()(int i) const
{
    if (!handler_->handleReport(error1(i))) return false;
    if (!handler_->handleReport(error2(i))) return false;

    return true;
}

bool HandlerClass::handleReport(std::auto_ptr<EbClass> e)
{
    if (e.get()) // A valid pointer indicates error
    {
       e->setHandler(this);
       return false;
    }
    return true;
}

void HandlerClass::handleReport(E1Class* e)
{
    // Insert report handling code,
    // like issuing error messages here
    std::cerr << "Error 1 detected: ";
}

void HandlerClass::handleReport(E2Class* e)
{
    // Insert report handling code,
    // like issuing error messages here
    std::cerr << "Error 2 detected: ";
}

void E1Class::setHandler(HandlerClass* h)
{
    h->handleReport(this);
}

void E2Class::setHandler(HandlerClass* h)
{
    h->handleReport(this);
}

int main()
{
    HandlerClass h;
    ValidatorClass v(&h);

    for (int i=0;i<6;++i)
    {
       if (v(i))
       {std::cout<< i << " is OK" << std::endl; }
       else
       {std::cout<< i << " is invalid" << std::endl; }
    }

    return(0);
}

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