iterator for derived class of std::vector

[Thomas]

I am compiling with g++ the fol. class:

template<typename E>

class C_vector_ : public std::vector<E>

{

private:

typedef std::vector<EVBASE_;

public:

void stream(void)

{

VBASE_::const_iterator it;

f or( it=this->begin(); it< this->end(); it++ )

cout << endl << *it;

return

}

};//eoClass: C_Vector

At <VBASE_::const_iterator it;the compiler shows the error message <

error: expected `;' before "it">

With MSC V6. there is no compiler error.

Regards Thomas

[mlimber]

Thomas wrote:

I am compiling with g++ the fol. class:

template<typename E>

class C_vector_ : public std::vector<E>

{

private:

typedef std::vector<EVBASE_;

public:

void stream(void)

{

VBASE_::const_iterator it;

f or( it=this->begin(); it< this->end(); it++ )

cout << endl << *it;

return

}

};//eoClass: C_Vector

At <VBASE_::const_iterator it;the compiler shows the error message <

error: expected `;' before "it">

See this FAQ:

http://parashift.com/c++-faq-lite/te...html#faq-35.18

But std::vector is not intended as a base class (it's destructor is not
virtual, for instance). Better practice would be to instead make a
wrapper class or, if you just want streaming capability, a
free-standing function (perhaps ostream& operator<<( ostream&, const
vector<T>& ) ).

Cheers! --M

[Ron Natalie]

Thomas wrote:

>
VBASE_::const_iterator it;

typename VBASE_::const_iterator it;

Qualified dependent type.

At <VBASE_::const_iterator it;the compiler shows the error message <

error: expected `;' before "it">

With MSC V6. there is no compiler error.

V6 is old and busted. G++ is new hotness.

[Thomas]

"Ron Natalie" <ro*@spamcop.netschrieb im Newsbeitrag
news:45*********************@news.newshosting.com. ..

Thomas wrote:

>>
VBASE_::const_iterator it;

typename VBASE_::const_iterator it;

Qualified dependent type.

>At <VBASE_::const_iterator it;the compiler shows the error message <

error: expected `;' before "it">

With MSC V6. there is no compiler error.

V6 is old and busted. G++ is new hotness.

Thank You Ron, that was the looked-for constructive contribution.

[Thomas]

"mlimber" <ml*****@gmail.comschrieb im Newsbeitrag
news:11**********************@s48g2000cws.googlegr oups.com...

Thomas wrote:

>I am compiling with g++ the fol. class:

template<typename E>

class C_vector_ : public std::vector<E>

{

private:

typedef std::vector<EVBASE_;

public:

void stream(void)

{

VBASE_::const_iterator it;

f or( it=this->begin(); it< this->end(); it++ )

cout << endl << *it;

return

}

};//eoClass: C_Vector

At <VBASE_::const_iterator it;the compiler shows the error message <

error: expected `;' before "it">

See this FAQ:

http://parashift.com/c++-faq-lite/te...html#faq-35.18

But std::vector is not intended as a base class (it's destructor is not
virtual, for instance). Better practice would be to instead make a
wrapper class or, if you just want streaming capability, a
free-standing function (perhaps ostream& operator<<( ostream&, const
vector<T>& ) ).

Cheers! --M

Thank You --M, but can You tell me please waht do You mean with "a wrapper
class"?

Best regards Thomas

[Thomas]

"mlimber" <ml*****@gmail.comschrieb im Newsbeitrag
news:11**********************@s48g2000cws.googlegr oups.com...

Thomas wrote:

>I am compiling with g++ the fol. class:

template<typename E>

class C_vector_ : public std::vector<E>

{

private:

typedef std::vector<EVBASE_;

public:

void stream(void)

{

VBASE_::const_iterator it;

f or( it=this->begin(); it< this->end(); it++ )

cout << endl << *it;

return

}

};//eoClass: C_Vector

At <VBASE_::const_iterator it;the compiler shows the error message <

error: expected `;' before "it">

See this FAQ:

http://parashift.com/c++-faq-lite/te...html#faq-35.18

But std::vector is not intended as a base class (it's destructor is not
virtual, for instance). Better practice would be to instead make a
wrapper class or, if you just want streaming capability, a
free-standing function (perhaps ostream& operator<<( ostream&, const
vector<T>& ) ).

Cheers! --M

Thank You --M,

for a long time, I did not derive classes from base classes, which do not
have a virtual destructor (and I detest it today), but sometimes I do not
know how to work around. But as far as I know, a virtual destructor is not
needed in all cases. F.i., is it imperative to have a virtual destructor in
the base class, if objekts of the derived class will only be deleted via a
pointer to that objects (not to a base-class-pointer)?

Best regards Thomas

[Diego Martins]

On Jan 24, 1:01 pm, "Thomas" <[e-mail]:

"mlimber" <[e-mail] im Newsbeitragnews:11**********************@s48g2000c ws.googlegroups.com...

Thomas wrote:

I am compiling with g++ the fol. class:

template<typename E>

class C_vector_ : public std::vector<E>

{

private:

typedef std::vector<EVBASE_;

public:

void stream(void)

{

VBASE_::const_iterator it;

f or( it=this->begin(); it< this->end(); it++ )

cout << endl << *it;

return

}

};//eoClass: C_Vector

At <VBASE_::const_iterator it;the compiler shows the error message <

error: expected `;' before "it">

See this FAQ:

http://parashift.com/c++-faq-lite/te...html#faq-35.18

But std::vector is not intended as a base class (it's destructor is not
virtual, for instance). Better practice would be to instead make a
wrapper class or, if you just want streaming capability, a
free-standing function (perhaps ostream& operator<<( ostream&, const
vector<T>& ) ).

Cheers! --MThank You --M,

for a long time, I did not derive classes from base classes, which do not
have a virtual destructor (and I detest it today), but sometimes I do not
know how to work around. But as far as I know, a virtual destructor is not
needed in all cases. F.i., is it imperative to have a virtual destructor in
the base class, if objekts of the derived class will only be deleted via a
pointer to that objects (not to a base-class-pointer)?

Best regards Thomas

they like to abuse the rule: "base classes must have a virtual
destructor" due to safety

but classes that do not have virtual functions seldom need virtual
destructors. so, I like the gcc warning: "class has virtual functions,
but does not have virtual destructor"

you can safely inherit from vector<Tif you do not make deletion from
base (e.g.: raw and smart pointers). period

[news.t-online.de]

"Diego Martins" <jo********@gmail.comschrieb im Newsbeitrag
news:11*********************@a75g2000cwd.googlegro ups.com...

>

On Jan 24, 1:01 pm, "Thomas" <[e-mail]:

>"mlimber" <[e-mail] im
Newsbeitragnews:11**********************@s48g2000 cws.googlegroups.com...

Thomas wrote:
I am compiling with g++ the fol. class:

>template<typename E>

>class C_vector_ : public std::vector<E>

> {

> private:

> typedef std::vector<EVBASE_;

> public:

> void stream(void)

> {

> VBASE_::const_iterator it;

> f or( it=this->begin(); it< this->end(); it++ )

> cout << endl << *it;

> return

> }

> };//eoClass: C_Vector

>At <VBASE_::const_iterator it;the compiler shows the error message
<

>error: expected `;' before "it">

See this FAQ:

>http://parashift.com/c++-faq-lite/te...html#faq-35.18

But std::vector is not intended as a base class (it's destructor is not
virtual, for instance). Better practice would be to instead make a
wrapper class or, if you just want streaming capability, a
free-standing function (perhaps ostream& operator<<( ostream&, const
vector<T>& ) ).

Cheers! --MThank You --M,

for a long time, I did not derive classes from base classes, which do not
have a virtual destructor (and I detest it today), but sometimes I do not
know how to work around. But as far as I know, a virtual destructor is
not
needed in all cases. F.i., is it imperative to have a virtual destructor
in
the base class, if objekts of the derived class will only be deleted via
a
pointer to that objects (not to a base-class-pointer)?

Best regards Thomas

they like to abuse the rule: "base classes must have a virtual
destructor" due to safety

but classes that do not have virtual functions seldom need virtual
destructors. so, I like the gcc warning: "class has virtual functions,
but does not have virtual destructor"

you can safely inherit from vector<Tif you do not make deletion from
base (e.g.: raw and smart pointers). period

Hello Diego,
I agree absolutely and IMHO one can inherit also from a base class having no
virtual destructor, if the derived class does not create objects on the
heap.
But always try to respect Your mentioned safety rules.

Nevertheless, I do not know why I get the compiler error in the original
stated problem.

Regards Thomas