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Use const_cast to modify member variable?

How can I modify member variable inside class if member function has
const like mem_Func(void) const. Please do not offer the keyword --
mutable. I want to know if keyword -- const_cast can be done.

If mutable is only the solution, I will follow not to use const_cast.
Jul 1 '08 #1
1 2339

"Immortal Nephi" <Im************ @satx.rr.coma écrit dans le message de
news: 1d************* *************** **...legroup s.com...
How can I modify member variable inside class if member function has
const like mem_Func(void) const. Please do not offer the keyword --
mutable. I want to know if keyword -- const_cast can be done.

If mutable is only the solution, I will follow not to use const_cast.
Ok it is Evil but you can do it.

struct EvilClass
{
void EvilFunct() const;
int _a;
};

void EvilClass::Evil Funct() const
{
int& tmp = const_cast<int& >(_a);
tmp = 5; // now _a == 5
}
You can also define a template function if you have many variables like
that.

struct EvilClass
{
void EvilFunct() const;

template<typena me T>
void EvilSet(T const& val, T const& NewVal) const;

int _a;
};

void EvilClass::Evil Funct() const
{
EvilSet(_a, 5); // much cleaner but maybe also much evil
}

template<typena me T>
void EvilClass::Evil Set(T const& val, T const& NewVal) const
{
T& tmp = const_cast<T&>( val);
tmp = NewVal;
}

------------------------

Eric Pruneau
Jul 1 '08 #2

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