Thread: about properties

i have 1 nice code for properties, but i want a direct code(with lambdas):

property <string> propertyname(std::function<string(void)>,std::func tion<void(string));
can anyone advice me doing these code?
i can do the code, but the overloading operators make me 'crazy' to understand them correctly

finally i have 1 code to show you:

Code:

template <typename T>
class property
{
private:
    std::function<void(void)> getf;
    std::function<void(void)> setf;
public:
    property(std::function<void(void)> GetFunction,std::function<T(void)> SetFunction)
    {
        setf=SetFunction;
        getf=GetFunction;
    }
    property& operator=(T value)
    {
        SetFunction(value);
    }

    T& operator=(property value)
    {
        return GetFunction();
    }
};

but i'm getting 1 error now:
"error: there are no arguments to 'GetFunction' that depend on a template parameter, so a declaration of 'GetFunction' must be available [-fpermissive]"
so what i'm doing wrong?

i found my error lol

Code:

template <typename T>
class property
{
private:
    std::function<void(void)> getf;
    std::function<void(void)> setf;
public:
    property(std::function<void(void)> GetFunction,std::function<T(void)> SetFunction)
    {
        setf=SetFunction;
        getf=GetFunction;
    }
    property& operator=(T value)
    {
        setf(value);
    }

    T& operator=(property value)
    {
        return getf();
    }
};

now i will test it
but can anyone tell me about the overloading operator = ?
i'm asking, because i always fail with it

true it's confused and i did that lol
can anyone advice, please?

I don't see that line in your code. If you want to initialize a member variable, that's not where the initializer goes. (That's what the constructor is for.)

Originally Posted by tabstop

I don't see that line in your code. If you want to initialize a member variable, that's not where the initializer goes. (That's what the constructor is for.)

on second example. and i use 2 construtors.

(i will fix 1 thing on code)

If you can't count all the way up to zero, we've got bigger problems. A constructor would look like

Code:

test::test(parameters go here) : initializers go here {statements go here};

Originally Posted by tabstop

If you can't count all the way up to zero, we've got bigger problems. A constructor would look like

Code:

test::test(parameters go here) : initializers go here {statements go here};

now i understand what you mean:

Code:

#include <iostream>
#include <functional>

using namespace std;

template <typename T>
class property
{
private:
    T PropertyValue;
    std::function<void(void)> getf;
    std::function<void(T a)> setf;
public:
    property()
    {
        //nothing
    };

    property(std::function<void(void)> GetFunction,std::function<T(void)> SetFunction) : getf(NULL),getf(NULL)
    {
        setf=SetFunction;
        getf=GetFunction;
    }

    property& operator=(T value)
    {
        if(setf==NULL)
            PropertyValue=value;
        else
            setf(value);
        return *this;
    }

    T& operator=(property value)
    {
        if(getf==NULL)
            return PropertyValue;
        else
            return getf();
    }

    friend ostream& operator<<(ostream& os, const property& dt)
    {
        os << dt.PropertyValue;
        return os;
    }

    friend istream& operator>>(istream &input,property &dt)
    {
        input>>dt.PropertyValue;
        return input;
    }
};

void sethi(string b)
{
    b = b + " hi";
}

string gethi()
{
    return "hello";
}

class test
{
public:
    property<string> Name(&sethi,&gethi);
    property<int> Age;
};

test a;
int main()
{
    a.Name="joaquim "  "Miguel";
    a.Age=10+15;
    cout << a.Name << endl;
    cout << "what is your name?\n";
    cin >> a.Name;
    cout << "your name is: " << a.Name << endl;
    return 0;
}

but i continue with same errors

If you understand what I meant, then why are there still no constructors for test?

Originally Posted by tabstop

If you understand what I meant, then why are there still no constructors for test?

Code:

class test
{
public:
    test() : Age(30),Name("Joaquim")
    {
        ;
    }
    property<string> Name(&sethi,&gethi);
    property<int> Age;
};

test a;

Originally Posted by phantomotap

O_o

I appreciate that you are new, but you are doing yourself no favors with this "HURRY RESPOND!" style of posting.

Read over the thread again, you have what you need to fix your code if you'd take a few minutes to actually apply what people are telling you.

Soma

sorry. i understand that i must initializate the values and do construtors, or i can get unexpected results. but i'm confuse how i can fix these code

Originally Posted by joaquim

Code:

class test
{
public:
    test() : Age(30),Name("Joaquim")
    {
        ;
    }
    property<string> Name(&sethi,&gethi);
    property<int> Age;
};

test a;

I don't know how much booze you've gotten through this far on a Saturday night, but you haven't hit the Ballmer peak yet (or worse, you're past it already). Look at your constructor -- do you think property<string> has a constructor that takes a string argument? Why would you think that? And you cannot try to initialize a member variable at its declaration; that's what the initializer list of the constructor is for.

Code:

test::test(take some information here, like sethi, gethi, and age) : initialize some member variables here, like Name(sethi, gethi), Age(age) {any other statements go here;}