expected class-name before '{'

[bubzilla]

Hi,

i´ve got about 10 headerfiles with implemented classes. Now when i try

to compile them i get the following message:


In file included from Proxy/ServerCnx.hh:36 ,
from Proxy/Payload.hh:30,
...
from main.cc:28
Proxy/Interface.hh:83 : error: expected class-name before '{'


The Interface.hh looks like this:


class Module : public ClientCnx{...}


so far, i realisied that ClientCnx isn´t declarated. So I tried to
make a forward Declaration
by using


class ClientCnx;


but now, the compiler says:


Proxy/Interface.hh:83 : error_ invalid use of undefined type `ClientCnx`

Proxy/Interface.hh:30 : error_ forward declaration of `ClientCnx`


now what can i do to fix this prob ?!?

[Stuart Redmann]

Re: expected class-name before '{'

bubzilla wrote:

Hi,
>
i´ve got about 10 headerfiles with implemented classes. Now when i try
to compile them i get the following message:
>
In file included from Proxy/ServerCnx.hh:36 ,
from Proxy/Payload.hh:30,
...
from main.cc:28
Proxy/Interface.hh:83 : error: expected class-name before '{'
>
The Interface.hh looks like this:
>
class Module : public ClientCnx{...}
>
so far, i realisied that ClientCnx isn´t declarated. So I tried to
make a forward Declaration
by using
>
class ClientCnx;
>

A forward declaration isn't sufficient here, the compiler needs to see
the whole declaration of the base classes.

>
but now, the compiler says:
>
Proxy/Interface.hh:83 : error_ invalid use of undefined type `ClientCnx`
>
Proxy/Interface.hh:30 : error_ forward declaration of `ClientCnx`
>
>
now what can i do to fix this prob ?!?
>

Find the header file that declares the base class and include it before
the declaration of Module.

Regards,
Stuart

[Gavin Deane]

Re: expected class-name before '{'


bubzilla wrote:

Hi,
>
i´ve got about 10 headerfiles with implemented classes. Now when i try
>
to compile them i get the following message:
>
>
In file included from Proxy/ServerCnx.hh:36 ,
from Proxy/Payload.hh:30,
...
from main.cc:28
Proxy/Interface.hh:83 : error: expected class-name before '{'
>
>
The Interface.hh looks like this:
>
>
class Module : public ClientCnx{...}
>
>
so far, i realisied that ClientCnx isn´t declarated.

That certainly sounds like a reasonable conclusion.

So I tried to make a forward Declaration

But why do you think a forward declaration would help?

by using
>
>
class ClientCnx;
>
>
but now, the compiler says:
>
>
Proxy/Interface.hh:83 : error_ invalid use of undefined type `ClientCnx`
>
Proxy/Interface.hh:30 : error_ forward declaration of `ClientCnx`
>
>
now what can i do to fix this prob ?!?

ClientCnx is a base class of Module and the compiler needs to know the
full definition of ClientCnx before it sees Module. A forward
declaration just tells the compiler that ClientCnx is the name of a
class. That is not enough. You need to include the entire class
definition of ClientCnx. If ClientCnx is defined in a header, #include
that header above the definition of class Module.

Gavin Deane

[bubzilla]

Re: expected class-name before '{'

Ok, i had the same solution. So i tried to change the header includes,
but some how i did got a way so that no error appears!

so, do i have to try again, to find the right include order.

Or can it be that there is somekind of circle that has to be solved in
a other way?
I'm not familiar how the Compiler brings the headerfiles together?

[Morten V Pedersen]

Re: expected class-name before '{'

bubzilla wrote:

Ok, i had the same solution. So i tried to change the header includes,
but some how i did got a way so that no error appears!

So it's working now?

>
so, do i have to try again, to find the right include order.
>
Or can it be that there is somekind of circle that has to be solved in
a other way?
I'm not familiar how the Compiler brings the headerfiles together?
>

It's the preprocessor that brings the header files together..

You'll be getting multiple defined errors if you have cyclic includes..
You can avoid that problem by using include guards:

#ifndef SOME_UNIQUE_LAB EL
#define SOME_UNIQUE_LAB EL
code;
#endif


--
// morten

[Stuart Redmann]

Re: expected class-name before '{'

bubzilla wrote:

Ok, i had the same solution. So i tried to change the header includes,
but some how i did got a way so that no error appears!

That's good.

so, do i have to try again, to find the right include order.
>
Or can it be that there is somekind of circle that has to be solved in
a other way?
I'm not familiar how the Compiler brings the headerfiles together?

Use include guards, as Morten suggests.

If you build a class hierarchy you should always include any base
classes in your header files before you declare the derived class:

In base.h:
#ifndef BASE_H_INCLUDED
# define BASE_H_INCLUDED
class Base
{...};
#endif

In Derived.h:
#ifndef DERIVED_H_INCLU DED
# define DERIVED_H_INCLU DED
class Derived : public Base
{...};
#endif

If you have classes that have pointers to each other, you need forward
declarations:

In A.h:
// Forward declaration of class B. Now the compiler
// can handle pointers and references to class B,
// provided they are not de-referenced.
class B;
class A
{
// Pointer to instance of class B
class B* b;
};

in B.h:
class B
{
// Pointer to instance of class A. Note the
// class keyword, that is used as forward declaration
// of name A.
class A* b;
};

Regards,
Stuart

[bubzilla]

Re: expected class-name before '{'


:-(

strange, i use include guards,
and i use forward declarations for owner ship

that´s why i posted in this group cause i just can´t find a reason!

[bubzilla]

Re: expected class-name before '{'

Help help help, i´m haven´t found a solution yet! :-(

Here is the order how the my Header files are included:

main.cc
#include "Proxy/RtspProxy.hh"

RtspProxy.hh
#include "InterfaceModul e.hh"

InterfaceModule .hh
#include "ServerCnx. hh"

ServerCnx.hh
#include "RtspProxy. hh"

RtspProxy.hh
#include "InterfaceModul e.hh" NO_MORE
#include "ClientCnx. hh"

ClientCnx.hh
#include "Payload.hh "

Payload.hh
#include "ServerCnx. hh" NO_MORE
Payload.code

#include "ClientStream.h h"
ClientCnx.code

#include "ServerCnx. hh" NO_MORE
#include "RtspMsg.hh "

RtspMsg.hh
RtspMsg.code

#include "RtspController .hh"

RtspController. hh
#include "ClientCnx. hh" NO_MORE
#include "SdpMsg.hh"

SdpMsg.hh
#include"RtspMs g.hh" NO_MORE
SdpMsg.code

#include "RtspMsg.hh " NO_MORE
#include "Scheduler/Scheduler.hh"

Scheduler.hh
Scheduler.code

#include "Socket.hh"

Socket.hh
Socket.code

#include "Utils/Exception.hh"
Utils/Exception.hh
Utils/Exception.code

RtspController. code

#include "Socket.hh" NO_MORE
#include "Scheduler/Scheduler.hh" NO_MORE
#include "Utils/membind.hh"

membind.hh
membind.code

RtspProxy.code

#include "Payload.hh " NO_MORE
#include "InterfaceModul e.hh" NO_MORE
#include "ServerStream.h h"

ServerStream.hh
#include "ServerCnx. hh" NO_MORE
#include "Socket.hh" NO_MORE
#include "Scheduler/Scheduler.hh" NO_MORE
ServerStream.co de

#include "RtspController .hh" NO_MORE
#include "RtspMsg.hh " NO_MORE
#include "InterfaceList. hh"

InterfaceList.h h
InterfaceList.c ode

#include "Socket.hh" NO_MORE
ServerCnx::code

#include "ClientCnx. hh" NO_MORE
#include "InterfaceList. hh" NO_MORE
InterfaceModule ::code

#include "ClientCnx. hh" NO_MORE
#include "ServerCnx. hh" NO_MORE
#include "RtspMsg.hh " NO_MORE
#include "RtspController .hh" NO_MORE
#include "Socket.hh" NO_MORE
#include "Scheduler/Scheduler.hh" NO_MORE
#include "Utils/membind.hh"

membind.hh
membind.code

RtspProxy::code
main::code



now i still get a error :

in file: included from RtspProxy.hh:50 ,
from ServerCnx.hh:34 ,
from Payload.hh:30,
from ClientCnx.hh:34 ,
from ClientStream.hh :33,
from ClientStream.cc :23:
InterfaceModule .hh:87: error: incvlad use of undefined type `struct
ClientCnx'
RtspController. hh:59: error: forward declaration of `struct ClientCnx'


OK, now in RtspController. hh I use a forward Declaration of ClientCnx
cause I need the Class as the Type of an Parameter:

ClientRtspContr oller( ClientCnx* )

but later I need the Class as a Baseclass in InterfaceModule .hh:

class PassthroughModu le : public ClientCnx

i don´t get this thing fxxxing solved! ÄÄÄÄÄÄÄ

[Victor Bazarov]

Re: expected class-name before '{'

bubzilla wrote:

Help help help, i´m haven´t found a solution yet! :-(
>
Here is the order how the my Header files are included:
>
[...]

Make sure none of your headers have double inclusion guards that
share the same macro -- a common copy-paste mistake.

Without seeing the code nothing else springs to mind.

V
--
Please remove capital 'A's when replying by e-mail
I do not respond to top-posted replies, please don't ask

[Stuart Redmann]

Re: expected class-name before '{'

bubzilla wrote:

Help help help, i´m haven´t found a solution yet! :-(
>
Here is the order how the my Header files are included:

[snipped include graph]

>
now i still get a error :
>
in file: included from RtspProxy.hh:50 ,
from ServerCnx.hh:34 ,
from Payload.hh:30,
from ClientCnx.hh:34 ,
from ClientStream.hh :33,
from ClientStream.cc :23:
InterfaceModule .hh:87: error: incvlad use of undefined type `struct
ClientCnx'
RtspController. hh:59: error: forward declaration of `struct ClientCnx'
>
>
OK, now in RtspController. hh I use a forward Declaration of ClientCnx
cause I need the Class as the Type of an Parameter:
>
ClientRtspContr oller( ClientCnx* )
>
but later I need the Class as a Baseclass in InterfaceModule .hh:
>
class PassthroughModu le : public ClientCnx
>
i don´t get this thing fxxxing solved! ÄÄÄÄÄÄÄ

Could you make a copy of your source tree and take away all the
definitions that are not necessary for us to see? Take out all members
that are of a different type than the above classes. Also take out all
members that are pointers or references to any of the above classes.
Take away all base classes that don't belong to the offending hierarchy.

You should end up with classes that look like the following:

ClientCnx.hh (just an example, your code would certainly look different):
class ClientCnx : public InterfaceModule // Base class declaration that
// needs to see the class
// InterfaceModule
{
// Member that needs to see the class Payload.
Payload m_Payload;
};

Then post the headers and the offending .cpp file (that only needs to
contain the offending includes). Then we can have a look at it and
(hopefully) help you.

Stuart

[bubzilla]

Re: expected class-name before '{'

There are 3 headers:

InterfaceModule .hh
RtspController. hh
ClientCnx.hh

InterfaceModule .hh has a Derived Class and the Base is ClientCnx in
CLientCnx.hh,
RtspController has a Pointer on his owner, which is of type ClientCnx
and ClientCnx
like this


InterfaceModule .hh:
class Derived : public ClientCnx{ ... };

RtspController. hh:
class Controller {
ClientCnx ptr;
};

ClientCnx.hh:
class ClientCnx{
Controller ptr;
}

so, InterfaceModule .hh needs ClientCnx.hh be be included for the Base:
ClientCnx
and
ClientCnx.hh needs RtspController. hh to be included an i need a forward
declaration in RtspController. hh for ClientCnx

but then i compile, an error accures like

InterfaceModule .hh: error: incvlad use of undefined type `struct
ClientCnx'
RtspController. hh: error: forward declaration of `struct ClientCnx'

???

[Earl Purple]

Re: expected class-name before '{'


bubzilla wrote:

There are 3 headers:
>
InterfaceModule .hh
RtspController. hh
ClientCnx.hh
>
InterfaceModule .hh has a Derived Class and the Base is ClientCnx in
CLientCnx.hh,
RtspController has a Pointer on his owner, which is of type ClientCnx
and ClientCnx
like this

It is preferable that your header includes the header it needs so that
your source files can include the headers they need in any order.

When you have a hierarchy of classes where one is an abstract base and
the other is simply an implementation that has no extra public methods,
it is preferable that only the implementation file for the derived
class and any closely associated classes know about the derived class
(thus including its header).

InterfaceModule .hh:
class Derived : public ClientCnx{ ... };
>
RtspController. hh:
class Controller {
ClientCnx ptr;
};

If Derived provides no new public methods of its own then most of your
source should be using ClientCnx, not Derived. Such source should be
including the header for ClientCnx (ClientCnx.hh) only.

ClientCnx.hh:
class ClientCnx{
Controller ptr;
}
>
so, InterfaceModule .hh needs ClientCnx.hh be be included for the Base:
ClientCnx
and
ClientCnx.hh needs RtspController. hh to be included an i need a forward
declaration in RtspController. hh for ClientCnx

What is Controller? You have called the member ptr so is it a pointer?
ClientCnx is a base class (possibly an abstract one). You haven't given
it any methods (nor terminated it with a semi-colon) but much of the
time abstract classes should not give away any of their implementation
detail, so if they do have any pointer members they should generally be
to only forwardly-declared classes. A lot of the time they will have no
member variables at all. Note that ClientCnx should also have either a
public virtual destructor or a protected non-virtual one.

but then i compile, an error accures like
>
InterfaceModule .hh: error: incvlad use of undefined type `struct
ClientCnx'

Because you didn't include it in the header. By the way, if the file is
called InterfaceModule .hh the class should probably be called
InterfaceModule and not Derived. InterfaceModule should be a type of
ClientCnx.

RtspController. hh: error: forward declaration of `struct ClientCnx'

It will need that forward declaration if it needs to know of ClientCnx
as a type but doesn't need to know anything else about it, i.e. its
size of any of its methods.

[Stuart Redmann]

Re: expected class-name before '{'

bubzilla wrote:

There are 3 headers:
>
InterfaceModule .hh
RtspController. hh
ClientCnx.hh
>
InterfaceModule .hh has a Derived Class and the Base is ClientCnx in
CLientCnx.hh,
RtspController has a Pointer on his owner, which is of type ClientCnx
and ClientCnx
like this
>
InterfaceModule .hh:
class Derived : public ClientCnx{ ... };
>
RtspController. hh:
class Controller {
ClientCnx ptr;

As you mentioned above, this should be a pointer (maybe this was the
fault all the time). In my example below I replaced this by
ClientCnx* ptr;

};
>
ClientCnx.hh:
class ClientCnx{
Controller ptr;

The same here.

}
>
so, InterfaceModule .hh needs ClientCnx.hh be be included for the Base:
ClientCnx
and
ClientCnx.hh needs RtspController. hh to be included an i need a forward
declaration in RtspController. hh for ClientCnx
>
but then i compile, an error accures like
>
InterfaceModule .hh: error: incvlad use of undefined type `struct
ClientCnx'
RtspController. hh: error: forward declaration of `struct ClientCnx'
>

Here is my version of the three headers:
------------------------------------------------
ClientCnx.hh:
------------------------------------------------
#ifndef _CLIENTCNX_HH
# define _CLIENTCNX_HH

// We don't need to see Controller here,
// since we only hold a pointer to this
// class.

// Forward declaration for Controller class.
class Controller;

class ClientCnx{
Controller* ptr;
};
#endif // _CLIENTCNX_HH

------------------------------------------------
RtspController. hh:
------------------------------------------------
#ifndef _RTSPCONTROLLER _HH
# define _RTSPCONTROLLER _HH


// We don't need to see ClientCnx here,
// since we only hold a pointer to this
// class.

// Forward declaration for ClientCnx class.
class ClientCnx;

class Controller
{
ClientCnx* ptr;
};

#endif // _RTSPCONTROLLER _HH
------------------------------------------------
InterfaceModule .hh:
------------------------------------------------
#ifndef _INTERFACEMODUL E_HH
# define _INTERFACEMODUL E_HH

// We need to see the whole definition
// of ClientCnx, since we derive from
// it.
#include "ClientCnx. hh"

class Derived : public ClientCnx
{
};

#endif // _INTERFACEMODUL E_HH
------------------------------------------------
main.cpp:
------------------------------------------------
#include "InterfaceModul e.hh"
int main ()
{
Derived Module;
return 0;
}

main.cpp compiles fine, although the compiler warns that the variable
Module is never used.

I hope this helps,
Stuart

[bubzilla]

Re: expected class-name before '{'


first of all: THANKX THANKX THANKX THANKX THANKX THANKX THANKX THANKX
THANKX THANKX THANKX THANKX THANKX THANKX THANKX THANKX THANKX THANKX
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THANKX THANKX THANKX THANKX THANKX THANKX THANKX THANKX THANKX THANKX
THANKX THANKX THANKX THANKX THANKX THANKX THANKX THANKX THANKX THANKX
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THANKX THANKX THANKX THANKX THANKX THANKX THANKX THANKX THANKX THANKX
THANKX THANKX THANKX THANKX THANKX THANKX THANKX THANKX THANKX THANKX
THANKX THANKX THANKX THANKX THANKX THANKX THANKX THANKX THANKX THANKX
THANKX THANKX THANKX THANKX THANKX

second: it don´t work yet

third: here are all my relevant files and their includes:


main.cc
#include "Proxy/RtspProxy.hh"


RtspProxy.hh
#include "InterfaceModul e.hh"
#include "RtspController .hh"
#include "ClientCnx. hh"
#include "ServerCnx. hh"
#include "RtspMsg.hh "
#include "Socket.hh"
#include "Scheduler/Scheduler.hh"
#include "Utils/membind.hh"


InterfaceModule .hh
#include "RtspController .hh"
#include "InterfaceList. hh"


RtspController. hh
#include "ClientCnx. hh"
#include "SdpMsg.hh"
#include "RtspMsg.hh "
#include "Scheduler/Scheduler.hh"
#include "Socket.hh"
#include "Utils/Exception.hh"


ClientCnx.hh
#include "InterfaceList. hh"
#include "RtspMsg.hh "
#include "Payload.hh "
#include "ClientStream.h h"


ServerCnx.hh
#include "RtspProxy. hh"
#include "Payload.hh "
#include "InterfaceModul e.hh"
#include "ServerStream.h h"
#include "RtspController .hh"
#include "RtspMsg.hh "
#include "InterfaceList. hh"
#include "Socket.hh"


Payload.hh
#include "ServerCnx. hh"


ServerStream.hh
#include "ServerCnx. hh"
#include "Socket.hh"
#include "Scheduler/Scheduler.hh"



these are the includes in all headerfiles, some have no includes
my compiler says:

g++ -Wall -Woverloaded-virtual -Wno-long-long -pedantic -ansi -O0 -g
-fno-inline -I. -c -o main.o main.cc
g++ -Wall -Woverloaded-virtual -Wno-long-long -pedantic -ansi -O0 -g
-fno-inline -I. -c -o Proxy/ClientStream.o Proxy/ClientStream.cc
In file included from Proxy/RtspProxy.hh:50 ,
from Proxy/ServerCnx.hh:34 ,
from Proxy/Payload.hh:30,
from Proxy/ClientCnx.hh:34 ,
from Proxy/ClientStream.hh :33,
from Proxy/ClientStream.cc :23:
Proxy/InterfaceModule .hh:88: error: invalid use of undefined type
`struct satcom::rtspPro xy::ClientCnx'
Proxy/RtspController. hh:59: error: forward declaration of `struct
satcom::rtspPro xy::ClientCnx'
scons: *** [Proxy/ClientStream.o] Error 1
scons: building terminated because of errors.


and in RtspController. hh:59 is a forward declaration like this

...
class ClientCnx;
class RtspController : boost::noncopya ble
...

and in InterfaceModule .hh there is a class like this:

class PassthroughModu le
: public AbstractModule
, public ClientCnx
{
...

[bubzilla]

Re: expected class-name before '{'


first of all: THANKX THANKX THANKX THANKX THANKX THANKX THANKX THANKX
THANKX THANKX THANKX THANKX THANKX THANKX THANKX THANKX THANKX THANKX
THANKX THANKX THANKX THANKX THANKX THANKX THANKX THANKX THANKX THANKX
THANKX THANKX THANKX THANKX THANKX THANKX THANKX THANKX THANKX THANKX
THANKX THANKX THANKX THANKX THANKX THANKX THANKX THANKX THANKX THANKX
THANKX THANKX THANKX THANKX THANKX THANKX THANKX THANKX THANKX THANKX
THANKX THANKX THANKX THANKX THANKX THANKX THANKX THANKX THANKX THANKX
THANKX THANKX THANKX THANKX THANKX THANKX THANKX THANKX THANKX THANKX
THANKX THANKX THANKX THANKX THANKX THANKX THANKX THANKX THANKX THANKX
THANKX THANKX THANKX THANKX THANKX THANKX THANKX THANKX THANKX THANKX
THANKX THANKX THANKX THANKX THANKX THANKX THANKX THANKX THANKX THANKX
THANKX THANKX THANKX THANKX THANKX

second: it don´t work yet

third here are all my relevant files and their includes:




main.cc
#include "Proxy/RtspProxy.hh"


RtspProxy.hh
#include "InterfaceModul e.hh"
#include "RtspController .hh"
#include "ClientCnx. hh"
#include "ServerCnx. hh"
#include "RtspMsg.hh "
#include "Socket.hh"
#include "Scheduler/Scheduler.hh"
#include "Utils/membind.hh"


InterfaceModule .hh
#include "RtspController .hh"
#include "InterfaceList. hh"


RtspController. hh
#include "ClientCnx. hh"
#include "SdpMsg.hh"
#include "RtspMsg.hh "
#include "Scheduler/Scheduler.hh"
#include "Socket.hh"
#include "Utils/Exception.hh"


ClientCnx.hh
#include "InterfaceList. hh"
#include "RtspMsg.hh "
#include "Payload.hh "
#include "ClientStream.h h"


ServerCnx.hh
#include "RtspProxy. hh"
#include "Payload.hh "
#include "InterfaceModul e.hh"
#include "ServerStream.h h"
#include "RtspController .hh"
#include "RtspMsg.hh "
#include "InterfaceList. hh"
#include "Socket.hh"


Payload.hh
#include "ServerCnx. hh"


ServerStream.hh
#include "ServerCnx. hh"
#include "Socket.hh"
#include "Scheduler/Scheduler.hh"



these are the includes in all headerfiles, some have no includes
my compiler says:

g++ -Wall -Woverloaded-virtual -Wno-long-long -pedantic -ansi -O0 -g
-fno-inline -I. -c -o main.o main.cc
g++ -Wall -Woverloaded-virtual -Wno-long-long -pedantic -ansi -O0 -g
-fno-inline -I. -c -o Proxy/ClientStream.o Proxy/ClientStream.cc
In file included from Proxy/RtspProxy.hh:50 ,
from Proxy/ServerCnx.hh:34 ,
from Proxy/Payload.hh:30,
from Proxy/ClientCnx.hh:34 ,
from Proxy/ClientStream.hh :33,
from Proxy/ClientStream.cc :23:
Proxy/InterfaceModule .hh:88: error: invalid use of undefined type
`struct satcom::rtspPro xy::ClientCnx'
Proxy/RtspController. hh:59: error: forward declaration of `struct
satcom::rtspPro xy::ClientCnx'
scons: *** [Proxy/ClientStream.o] Error 1
scons: building terminated because of errors.


and in RtspController. hh:59 is a forward declaration like this

...
class ClientCnx;
class RtspController : boost::noncopya ble
...

and in InterfaceModule .hh there is a class like this:

class PassthroughModu le
: public AbstractModule
, public ClientCnx
{
...