access to private members of internal class

[Shea Martin]

Class A
{
public:
class B;
int funct(const B &b);
};

Class A::B
{
private:
int _member;
};

int A::funct(const A::B &b)
{
return 10*b._member; //won't compile
}

////////////////////////////
The above code will not compile, as I get a error to the effect of
member _member not accessable from A::funct(const A::B&)

Is there anyway around this, short of declaring _member to be public?

Thanks,

~S

[John Harrison]

Re: access to private members of internal class


"Shea Martin" <smartin@arcis. com> wrote in message
news:Yljdc.4779 $G3.43042@local host...[color=blue]
> Class A
> {
> public:
> class B;
> int funct(const B &b);
> };
>
> Class A::B
> {
> private:
> int _member;
> };
>
> int A::funct(const A::B &b)
> {
> return 10*b._member; //won't compile
> }
>
> ////////////////////////////
> The above code will not compile, as I get a error to the effect of
> member _member not accessable from A::funct(const A::B&)
>
> Is there anyway around this, short of declaring _member to be public?
>
> Thanks,
>
> ~S[/color]

Make A a friend of B.

class A::B
{
friend class A;
...

john

[John Harrison]

Re: access to private members of internal class


"Shea Martin" <smartin@arcis. com> wrote in message
news:Yljdc.4779 $G3.43042@local host...[color=blue]
> Class A
> {
> public:
> class B;
> int funct(const B &b);
> };
>
> Class A::B
> {
> private:
> int _member;
> };
>
> int A::funct(const A::B &b)
> {
> return 10*b._member; //won't compile
> }
>
> ////////////////////////////
> The above code will not compile, as I get a error to the effect of
> member _member not accessable from A::funct(const A::B&)
>
> Is there anyway around this, short of declaring _member to be public?
>
> Thanks,
>
> ~S[/color]

Make A a friend of B.

class A::B
{
friend class A;
...

john

[Leor Zolman]

Re: access to private members of internal class

On Thu, 8 Apr 2004 22:24:00 +0100, "John Harrison"
<john_andronicu s@hotmail.com> wrote:
[color=blue]
>
>"Shea Martin" <smartin@arcis. com> wrote in message
>news:Yljdc.477 9$G3.43042@loca lhost...[color=green]
>> Class A
>> {
>> public:
>> class B;
>> int funct(const B &b);
>> };
>>
>> Class A::B
>> {
>> private:
>> int _member;
>> };
>>
>> int A::funct(const A::B &b)
>> {
>> return 10*b._member; //won't compile
>> }
>>
>> ////////////////////////////
>> The above code will not compile, as I get a error to the effect of
>> member _member not accessable from A::funct(const A::B&)
>>
>> Is there anyway around this, short of declaring _member to be public?
>>
>> Thanks,
>>
>> ~S[/color]
>
>Make A a friend of B.
>
>class A::B
>{
> friend class A;
> ...
>
>john[/color]

Alternatively, /if/ A's functions don't need to /change/ the value of
_member, then having A::B provide a public accessor function would be
another possibility. (But that's a big "if", since this is evidently not
the code Shea actually tried to compile.)
-leor
[color=blue]
>[/color]

--
Leor Zolman --- BD Software --- www.bdsoft.com
On-Site Training in C/C++, Java, Perl and Unix
C++ users: Download BD Software's free STL Error Message Decryptor at:

https://www.bdsoft.com/tools/stlfilt.html

[Leor Zolman]

Re: access to private members of internal class

On Thu, 8 Apr 2004 22:24:00 +0100, "John Harrison"
<john_andronicu s@hotmail.com> wrote:
[color=blue]
>
>"Shea Martin" <smartin@arcis. com> wrote in message
>news:Yljdc.477 9$G3.43042@loca lhost...[color=green]
>> Class A
>> {
>> public:
>> class B;
>> int funct(const B &b);
>> };
>>
>> Class A::B
>> {
>> private:
>> int _member;
>> };
>>
>> int A::funct(const A::B &b)
>> {
>> return 10*b._member; //won't compile
>> }
>>
>> ////////////////////////////
>> The above code will not compile, as I get a error to the effect of
>> member _member not accessable from A::funct(const A::B&)
>>
>> Is there anyway around this, short of declaring _member to be public?
>>
>> Thanks,
>>
>> ~S[/color]
>
>Make A a friend of B.
>
>class A::B
>{
> friend class A;
> ...
>
>john[/color]

Alternatively, /if/ A's functions don't need to /change/ the value of
_member, then having A::B provide a public accessor function would be
another possibility. (But that's a big "if", since this is evidently not
the code Shea actually tried to compile.)
-leor
[color=blue]
>[/color]

--
Leor Zolman --- BD Software --- www.bdsoft.com
On-Site Training in C/C++, Java, Perl and Unix
C++ users: Download BD Software's free STL Error Message Decryptor at:

https://www.bdsoft.com/tools/stlfilt.html

[Shea Martin]

Re: access to private members of internal class

John Harrison wrote:[color=blue]
> "Shea Martin" <smartin@arcis. com> wrote in message
> news:Yljdc.4779 $G3.43042@local host...
>[color=green]
>>Class A
>>{
>>public:
>> class B;
>> int funct(const B &b);
>>};
>>
>>Class A::B
>>{
>>private:
>> int _member;
>>};
>>
>>int A::funct(const A::B &b)
>>{
>> return 10*b._member; //won't compile
>>}
>>
>>////////////////////////////
>>The above code will not compile, as I get a error to the effect of
>>member _member not accessable from A::funct(const A::B&)
>>
>>Is there anyway around this, short of declaring _member to be public?
>>
>>Thanks,
>>
>>~S[/color]
>
>
> Make A a friend of B.
>
> class A::B
> {
> friend class A;
> ...
>
> john
>
>[/color]
I already tried this, and get this error message:
"A.h line 4, Error: Iterator is not a structure tag."

I have tried using Sun's CC 5.0 and 5.6 beta compilers.

~S

[Shea Martin]

Re: access to private members of internal class

John Harrison wrote:[color=blue]
> "Shea Martin" <smartin@arcis. com> wrote in message
> news:Yljdc.4779 $G3.43042@local host...
>[color=green]
>>Class A
>>{
>>public:
>> class B;
>> int funct(const B &b);
>>};
>>
>>Class A::B
>>{
>>private:
>> int _member;
>>};
>>
>>int A::funct(const A::B &b)
>>{
>> return 10*b._member; //won't compile
>>}
>>
>>////////////////////////////
>>The above code will not compile, as I get a error to the effect of
>>member _member not accessable from A::funct(const A::B&)
>>
>>Is there anyway around this, short of declaring _member to be public?
>>
>>Thanks,
>>
>>~S[/color]
>
>
> Make A a friend of B.
>
> class A::B
> {
> friend class A;
> ...
>
> john
>
>[/color]
I already tried this, and get this error message:
"A.h line 4, Error: Iterator is not a structure tag."

I have tried using Sun's CC 5.0 and 5.6 beta compilers.

~S

[Leor Zolman]

Re: access to private members of internal class

On Fri, 09 Apr 2004 01:13:15 GMT, Shea Martin <shea@snowsquir rel.ca> wrote:
[color=blue][color=green]
>>
>> Make A a friend of B.
>>
>> class A::B
>> {
>> friend class A;
>> ...
>>
>> john
>>
>>[/color]
>I already tried this, and get this error message:
>"A.h line 4, Error: Iterator is not a structure tag."[/color]

The solution John gave would work for code "such as" that you've shown.

How can you possibly expect anyone to help you diagnose the cause of that
error message from the information you've supplied? We don't know what
Iterator is, or why the compiler would possibly think it is being used as a
structure tag (um, does it follow the word 'struct'?) But if you showed us
line 4 (or more) of A.h, we might at least /begin/ to be able to take wild
guesses...
-leor

--
Leor Zolman --- BD Software --- www.bdsoft.com
On-Site Training in C/C++, Java, Perl and Unix
C++ users: Download BD Software's free STL Error Message Decryptor at:

https://www.bdsoft.com/tools/stlfilt.html

[Leor Zolman]

Re: access to private members of internal class

On Fri, 09 Apr 2004 01:13:15 GMT, Shea Martin <shea@snowsquir rel.ca> wrote:
[color=blue][color=green]
>>
>> Make A a friend of B.
>>
>> class A::B
>> {
>> friend class A;
>> ...
>>
>> john
>>
>>[/color]
>I already tried this, and get this error message:
>"A.h line 4, Error: Iterator is not a structure tag."[/color]

The solution John gave would work for code "such as" that you've shown.

How can you possibly expect anyone to help you diagnose the cause of that
error message from the information you've supplied? We don't know what
Iterator is, or why the compiler would possibly think it is being used as a
structure tag (um, does it follow the word 'struct'?) But if you showed us
line 4 (or more) of A.h, we might at least /begin/ to be able to take wild
guesses...
-leor

--
Leor Zolman --- BD Software --- www.bdsoft.com
On-Site Training in C/C++, Java, Perl and Unix
C++ users: Download BD Software's free STL Error Message Decryptor at:

https://www.bdsoft.com/tools/stlfilt.html

[Shea Martin]

Re: access to private members of internal class

Leor Zolman wrote:[color=blue]
> On Fri, 09 Apr 2004 01:13:15 GMT, Shea Martin <shea@snowsquir rel.ca> wrote:
>
>[color=green][color=darkred]
>>>Make A a friend of B.
>>>
>>>class A::B
>>>{
>>> friend class A;
>>> ...
>>>
>>>john
>>>
>>>[/color]
>>
>>I already tried this, and get this error message:
>>"A.h line 4, Error: Iterator is not a structure tag."[/color]
>
>
> The solution John gave would work for code "such as" that you've shown.
>
> How can you possibly expect anyone to help you diagnose the cause of that
> error message from the information you've supplied? We don't know what
> Iterator is, or why the compiler would possibly think it is being used as a
> structure tag (um, does it follow the word 'struct'?) But if you showed us
> line 4 (or more) of A.h, we might at least /begin/ to be able to take wild
> guesses...
> -leor
>[/color]
Iterator is class B. I forgot to modify what I 'pasted'. I greatly apologize to
Leor for wasting his precious time, and even more precious thought.

I have not used 'friends' very often, and I made the misktake of declaring B to
be a friend of A's. Instead of what John had correctly suggested, Making A a
friend of B.

Thanks,

~S

[Shea Martin]

Re: access to private members of internal class

Leor Zolman wrote:[color=blue]
> On Fri, 09 Apr 2004 01:13:15 GMT, Shea Martin <shea@snowsquir rel.ca> wrote:
>
>[color=green][color=darkred]
>>>Make A a friend of B.
>>>
>>>class A::B
>>>{
>>> friend class A;
>>> ...
>>>
>>>john
>>>
>>>[/color]
>>
>>I already tried this, and get this error message:
>>"A.h line 4, Error: Iterator is not a structure tag."[/color]
>
>
> The solution John gave would work for code "such as" that you've shown.
>
> How can you possibly expect anyone to help you diagnose the cause of that
> error message from the information you've supplied? We don't know what
> Iterator is, or why the compiler would possibly think it is being used as a
> structure tag (um, does it follow the word 'struct'?) But if you showed us
> line 4 (or more) of A.h, we might at least /begin/ to be able to take wild
> guesses...
> -leor
>[/color]
Iterator is class B. I forgot to modify what I 'pasted'. I greatly apologize to
Leor for wasting his precious time, and even more precious thought.

I have not used 'friends' very often, and I made the misktake of declaring B to
be a friend of A's. Instead of what John had correctly suggested, Making A a
friend of B.

Thanks,

~S

[SaltPeter]

Re: access to private members of internal class


<snip>[color=blue][color=green]
> >
> >[/color]
> I already tried this, and get this error message:
> "A.h line 4, Error: Iterator is not a structure tag."
>
> I have tried using Sun's CC 5.0 and 5.6 beta compilers.
>
> ~S[/color]

The problems i see with your code are

a) "Class" should be replaced by "class" (probably the error you are seeing
by compiler)
b) its unclear what your goal is (just wanting code to be compileable won't
help)
c) member variables of a class should not use the underscore as first
character
d) You should specify constructors with an initializer list to pass
"member_" a value when constructor is invoked (so you can at least test
without stepping the debugger)
e) specify a virtual destructor as well.
f) show minimal code used to invoke the object(s) construction(s) and
behaviours.

You could have friendified class A as mentioned in other posts but i'ld
prefer doing the same to the function instead (friend A::func(...)). But if
class A is composed of a class B, that just doesn't make sense. add a public
function to class B which has access to it's own private member instead.

[SaltPeter]

Re: access to private members of internal class


<snip>[color=blue][color=green]
> >
> >[/color]
> I already tried this, and get this error message:
> "A.h line 4, Error: Iterator is not a structure tag."
>
> I have tried using Sun's CC 5.0 and 5.6 beta compilers.
>
> ~S[/color]

The problems i see with your code are

a) "Class" should be replaced by "class" (probably the error you are seeing
by compiler)
b) its unclear what your goal is (just wanting code to be compileable won't
help)
c) member variables of a class should not use the underscore as first
character
d) You should specify constructors with an initializer list to pass
"member_" a value when constructor is invoked (so you can at least test
without stepping the debugger)
e) specify a virtual destructor as well.
f) show minimal code used to invoke the object(s) construction(s) and
behaviours.

You could have friendified class A as mentioned in other posts but i'ld
prefer doing the same to the function instead (friend A::func(...)). But if
class A is composed of a class B, that just doesn't make sense. add a public
function to class B which has access to it's own private member instead.

[John Harrison]

Re: access to private members of internal class

> c) member variables of a class should not use the underscore as first[color=blue]
> character[/color]

Why? I do this all the time. I get moaned at on style grounds but I yet to
hear of concrete reason why its bad.

john

[John Harrison]

Re: access to private members of internal class

> c) member variables of a class should not use the underscore as first[color=blue]
> character[/color]

Why? I do this all the time. I get moaned at on style grounds but I yet to
hear of concrete reason why its bad.

john