C++ templates - design question

[TorAn]

Thank you for checking it out. Indeed, it does compile. I failed to carefully check my example against the real code. I'll make changes to match my situation exactly, test it, get my compile error and post modified example here.

[TorAn]

Here is the example that does not compile.

#include "stdafx.h"
#include <iostream>
#include <vector>
 
class A
{
};
 
class B
{
};
 
class Rule
{
public:
	enum ruleStatus
	{
		rsPassed = 1,
		rsFailed = 2,
		rsIncompleteData = 3
	};
 
	Rule()	{}
 
	virtual ~Rule() {}
 
	virtual enum ruleStatus isValid(int i, int j,				const int* tempval, const A& cfd) const;
	virtual enum ruleStatus isValid(int i, int j, const B& pair,const int* tempval, const A& cfd) const;
protected:
};
 
template <typename rulePolicy> class btRuleGeneric : public Rule
{
public:
	btRuleGeneric(): Rule(), _policy(*this){}
 
	enum ruleStatus isValid(int i, int j, const int* tempval, const A& cfd) const
	{
		return _policy.isValid(i, j, tempval,cfd);
	}
 
	enum ruleStatus isValid(int i, int j, const B& pair, const int* tempval, const A& cfd) const
	{
		return _policy.isValid(i, j, pair, tempval,cfd);
	}
private:
	rulePolicy _policy;
};
 
 
class basePolicy
{
public:
	basePolicy(const Rule& rule) : _rule(rule) {};
	virtual Rule::ruleStatus isValid(int i, int j,				  const int* tempval, const A& cfd) const;
	virtual Rule::ruleStatus isValid(int i, int j, const B& pair, const int* tempval, const A& cfd) const;
protected:
	mutable std::string _lasterror;
	const Rule& _rule;
};
 
class myPolicy : public basePolicy
{
public:
	myPolicy(const Rule& rule) : basePolicy(rule) {}
	Rule::ruleStatus isValid(int i, int j, 
		const int* tempval, const A& cfd) const;
 
// compiles OK if this method is uncommented
// 	Rule::ruleStatus isValid(int i, int j, const B& pair,
// 		const int* tempval, const A& cfd) const;
};
 
typedef std::vector<Rule*> coll;
 
int _tmain(int argc, _TCHAR* argv[])
{
	coll lst;
 
	Rule* rule = NULL;
	lst.push_back(new btRuleGeneric<myPolicy>());
 
	return 0;
}

#include "stdafx.h"
#include <iostream>
#include <vector>

class A
{
};

class B
{
};

class Rule
{
public:
	enum ruleStatus
	{
		rsPassed = 1,
		rsFailed = 2,
		rsIncompleteData = 3
	};

	Rule()	{}

	virtual ~Rule() {}

	virtual enum ruleStatus isValid(int i, int j,				const int* tempval, const A& cfd) const;
	virtual enum ruleStatus isValid(int i, int j, const B& pair,const int* tempval, const A& cfd) const;
protected:
};

template <typename rulePolicy> class btRuleGeneric : public Rule
{
public:
	btRuleGeneric(): Rule(), _policy(*this){}

	enum ruleStatus isValid(int i, int j, const int* tempval, const A& cfd) const
	{
		return _policy.isValid(i, j, tempval,cfd);
	}

	enum ruleStatus isValid(int i, int j, const B& pair, const int* tempval, const A& cfd) const
	{
		return _policy.isValid(i, j, pair, tempval,cfd);
	}
private:
	rulePolicy _policy;
};


class basePolicy
{
public:
	basePolicy(const Rule& rule) : _rule(rule) {};
	virtual Rule::ruleStatus isValid(int i, int j,				  const int* tempval, const A& cfd) const;
	virtual Rule::ruleStatus isValid(int i, int j, const B& pair, const int* tempval, const A& cfd) const;
protected:
	mutable std::string _lasterror;
	const Rule& _rule;
};

class myPolicy : public basePolicy
{
public:
	myPolicy(const Rule& rule) : basePolicy(rule) {}
	Rule::ruleStatus isValid(int i, int j, 
		const int* tempval, const A& cfd) const;

// compiles OK if this method is uncommented
// 	Rule::ruleStatus isValid(int i, int j, const B& pair,
// 		const int* tempval, const A& cfd) const;
};

typedef std::vector<Rule*> coll;

int _tmain(int argc, _TCHAR* argv[])
{
	coll lst;

	Rule* rule = NULL;
	lst.push_back(new btRuleGeneric<myPolicy>());

	return 0;
}

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[Zlatomir]

Aha, you have overloaded functions in there (i should have guessed that)

You will need to override all the overloads of a function, or introduce all of them (their implementation from the Base class) with the using directive.
Something like: <i didn't test it, i don't have VS right now (and saw stdafx... and other stuff that probably i should "hack" to work with Creator ), but it should work fine>

class myPolicy : public basePolicy
{
public:
	myPolicy(const Rule& rule) : basePolicy(rule) {}
 
        using basePolicy::isValid;  //this is what you need to do in every derived class, then you will have your desired behavior
 
	Rule::ruleStatus isValid(int i, int j, 
		const int* tempval, const A& cfd) const;
 
// compiles OK if this method is uncommented
// 	Rule::ruleStatus isValid(int i, int j, const B& pair,
// 		const int* tempval, const A& cfd) const;
};

class myPolicy : public basePolicy
{
public:
	myPolicy(const Rule& rule) : basePolicy(rule) {}
        
        using basePolicy::isValid;  //this is what you need to do in every derived class, then you will have your desired behavior
 
	Rule::ruleStatus isValid(int i, int j, 
		const int* tempval, const A& cfd) const;

// compiles OK if this method is uncommented
// 	Rule::ruleStatus isValid(int i, int j, const B& pair,
// 		const int* tempval, const A& cfd) const;
};

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[TorAn]

Thank you. You taught me the aspect of "using" directive that I did not encounter before.

A using declaration in a definition of a class A allows you to introduce a name of a data member or member function from a base class of A into the scope of A.