Question

Currently, I have some code as follows

template<typename Type>
Type* getValue(std::string name, bool tryUseGetter = true)
{
    if(tryUseGetter)
    {
        if(_properties[name]->hasGetter)
        {
            return (Type*)_properties[name]->getter();
        }
        return (Type*)_properties[name]->data;
    }
    else
    {
        return (Type*)_properties[name]->data;
    }
}

Is there a way to make tryUseGetter a compile time switch? i.e. move it to the template declaration so it’s something akin to this

template<typename Type, bool tryUseGetter = true>
...

Thanks.

Answer 1

You could use type cast operator and structure getValue as follows (usage syntax will be the same as with function) :

template<typename Type, bool tryUseGetter = true> 
struct getValue {};

template<typename Type>
struct getValue<Type, true> {
    getValue(const std::string& name) : name(name) {};
    operator Type*() const {
        if(_properties[name]->hasGetter) {
            return (Type*)_properties[name]->getter();
        }
        return (Type*)_properties[name]->data;
    }
private:
    const std::string& name;
};

template<typename Type>
struct getValue<Type, false> {
    getValue(const std::string& name) : name(name) {};
    operator Type*() const {
        return (Type*)_properties[name]->data;
    }
private:
    const std::string& name;
};

Usage:

int main () {
    int* i = getValue<int>( "TEST" ); // true by default
    Xstruct* x = getValue<Xstruct, false>( "XS" ); // false
}