Forward declaration with value class

[Jerome]

Hi all,

I'm trying to use forward declaration with value class but I don't succeed
in compiling my (quite simple) sample code.
This is my code I'm trying to compile (Visual Studio 2003)

namespace managedDll
{
public __value class VecDouble;
public __value class VecFloat
{
public:
void SetValue(VecDou ble vec)

{
// TODO
}

};

public __value class VecDouble
{

public:
void SetValue(VecFlo at vec)

{
// TODO
}

};
}

I've got the following error when compiling:
error C2027: use of undefined type 'managedDll::Ve cDouble'

Every think work fine if my SetValues methods have the signature (Vec(Double
| Float) &vec).
The problem is that putting a '&' is not logical because I want to call
methods from C# code and with this signature I should write the following
code

VecDouble vec = new VecDouble();
vecFloat.SetVal ue(ref vec);

Instead I want to call my methods in this way:
vecFloat.SetVal ue(new VecDouble())
The first solution is not acceptable !.

Does anyone encounter the same problem ?

Great thanks.
Jerome

[Eckart Haug]

Forward declaration by definition only works with pointers (VecDouble* vec) and refenences (VecDouble& vec).
This is because in this cases the parameter is just an address. If you pass an object by value, the compiler
creates a copy of the object on the stack - and therefore needs all the information of the object, e.g. how
many bytes it occupies, whether it has a copy constructor and so on.
Jerome wrote:

Hi all,

I'm trying to use forward declaration with value class but I don't succeed
in compiling my (quite simple) sample code.
This is my code I'm trying to compile (Visual Studio 2003)

namespace managedDll
{
public __value class VecDouble;
public __value class VecFloat
{
public:
void SetValue(VecDou ble vec)

{
// TODO
}

};

public __value class VecDouble
{

public:
void SetValue(VecFlo at vec)

{
// TODO
}

};
}

I've got the following error when compiling:
error C2027: use of undefined type 'managedDll::Ve cDouble'

Every think work fine if my SetValues methods have the signature (Vec(Double
| Float) &vec).
The problem is that putting a '&' is not logical because I want to call
methods from C# code and with this signature I should write the following
code

VecDouble vec = new VecDouble();
vecFloat.SetVal ue(ref vec);

Instead I want to call my methods in this way:
vecFloat.SetVal ue(new VecDouble())
The first solution is not acceptable !.

Does anyone encounter the same problem ?

Great thanks.
Jerome

[Jerome]

I know that ... and that's why I think there's a problem with managed C++
language.
It's not acceptable that a method you think taking a parameter as 'In' must
be signed by 'ref'
Of course the problem does not exists with reference class.

I'm still dreaming of a magic attribute or magic compilation option ... who
knows ? ... certainly Microsoft developpers ... Anyone from Microsoft Visual
Studio team to solve my issue or explain why it can't be possible ???

"Eckart Haug" <Ec*********@lu k.de> a écrit dans le message de
news:db******** **@aftlinux2.we rdohl.aft-werdohl.de...

Forward declaration by definition only works with pointers (VecDouble* vec) and refenences (VecDouble& vec). This is because in this cases the parameter is just an address. If you pass an object by value, the compiler creates a copy of the object on the stack - and therefore needs all the information of the object, e.g. how many bytes it occupies, whether it has a copy constructor and so on.
Jerome wrote:

Hi all,

I'm trying to use forward declaration with value class but I don't succeed in compiling my (quite simple) sample code.
This is my code I'm trying to compile (Visual Studio 2003)

namespace managedDll
{
public __value class VecDouble;
public __value class VecFloat
{
public:
void SetValue(VecDou ble vec)

{
// TODO
}

};

public __value class VecDouble
{

public:
void SetValue(VecFlo at vec)

{
// TODO
}

};
}

I've got the following error when compiling:
error C2027: use of undefined type 'managedDll::Ve cDouble'

Every think work fine if my SetValues methods have the signature (Vec(Double | Float) &vec).
The problem is that putting a '&' is not logical because I want to call
methods from C# code and with this signature I should write the following code

VecDouble vec = new VecDouble();
vecFloat.SetVal ue(ref vec);

Instead I want to call my methods in this way:
vecFloat.SetVal ue(new VecDouble())
The first solution is not acceptable !.

Does anyone encounter the same problem ?

Great thanks.
Jerome

[James Park]

How about something like this:
namespace managedDll
{
public __value class VecDouble;
public __value class VecFloat
{
public:
void SetValue(VecDou ble vec);
};

public __value class VecDouble
{
public:
void SetValue(VecFlo at vec)
{
// TODO
}
};

void VecFloat::SetVa lue(VecDouble vec)
{
// TODO
}
}

"Jerome" <jl****@NOSPAMm c.com> wrote in message
news:Oc******** ******@TK2MSFTN GP10.phx.gbl...

I know that ... and that's why I think there's a problem with managed C++
language.
It's not acceptable that a method you think taking a parameter as 'In'
must
be signed by 'ref'
Of course the problem does not exists with reference class.

I'm still dreaming of a magic attribute or magic compilation option ...
who
knows ? ... certainly Microsoft developpers ... Anyone from Microsoft
Visual
Studio team to solve my issue or explain why it can't be possible ???

"Eckart Haug" <Ec*********@lu k.de> a écrit dans le message de
news:db******** **@aftlinux2.we rdohl.aft-werdohl.de...

Forward declaration by definition only works with pointers (VecDouble*

vec) and refenences (VecDouble& vec).

This is because in this cases the parameter is just an address. If you

pass an object by value, the compiler

creates a copy of the object on the stack - and therefore needs all the

information of the object, e.g. how

many bytes it occupies, whether it has a copy constructor and so on.
Jerome wrote:

> Hi all,
>
> I'm trying to use forward declaration with value class but I don't succeed > in compiling my (quite simple) sample code.
> This is my code I'm trying to compile (Visual Studio 2003)
>
> namespace managedDll
> {
> public __value class VecDouble;
> public __value class VecFloat
> {
> public:
> void SetValue(VecDou ble vec)
>
> {
> // TODO
> }
>
> };
>
> public __value class VecDouble
> {
>
> public:
> void SetValue(VecFlo at vec)
>
> {
> // TODO
> }
>
> };
> }
>
> I've got the following error when compiling:
> error C2027: use of undefined type 'managedDll::Ve cDouble'
>
> Every think work fine if my SetValues methods have the signature (Vec(Double > | Float) &vec).
> The problem is that putting a '&' is not logical because I want to call
> methods from C# code and with this signature I should write the following > code
>
> VecDouble vec = new VecDouble();
> vecFloat.SetVal ue(ref vec);
>
> Instead I want to call my methods in this way:
> vecFloat.SetVal ue(new VecDouble())
> The first solution is not acceptable !.
>
> Does anyone encounter the same problem ?
>
> Great thanks.
> Jerome
>
>

[Jerome]

It works !
I try so much things that I don't try the simple one ...

Great thanks !

"James Park" <jp**********@S paMMEhotmail.co m> a écrit dans le message de
news:uO******** ******@tk2msftn gp13.phx.gbl...

How about something like this:
namespace managedDll
{
public __value class VecDouble;
public __value class VecFloat
{
public:
void SetValue(VecDou ble vec);
};

public __value class VecDouble
{
public:
void SetValue(VecFlo at vec)
{
// TODO
}
};

void VecFloat::SetVa lue(VecDouble vec)
{
// TODO
}
}

"Jerome" <jl****@NOSPAMm c.com> wrote in message
news:Oc******** ******@TK2MSFTN GP10.phx.gbl...

I know that ... and that's why I think there's a problem with managed C++
language.
It's not acceptable that a method you think taking a parameter as 'In'
must
be signed by 'ref'
Of course the problem does not exists with reference class.

I'm still dreaming of a magic attribute or magic compilation option ...
who
knows ? ... certainly Microsoft developpers ... Anyone from Microsoft
Visual
Studio team to solve my issue or explain why it can't be possible ???

"Eckart Haug" <Ec*********@lu k.de> a écrit dans le message de
news:db******** **@aftlinux2.we rdohl.aft-werdohl.de...

Forward declaration by definition only works with pointers (VecDouble*

vec) and refenences (VecDouble& vec).

This is because in this cases the parameter is just an address. If you

pass an object by value, the compiler

creates a copy of the object on the stack - and therefore needs all the

information of the object, e.g. how

many bytes it occupies, whether it has a copy constructor and so on.
Jerome wrote:
> Hi all,
>
> I'm trying to use forward declaration with value class but I don't

succeed

> in compiling my (quite simple) sample code.
> This is my code I'm trying to compile (Visual Studio 2003)
>
> namespace managedDll
> {
> public __value class VecDouble;
> public __value class VecFloat
> {
> public:
> void SetValue(VecDou ble vec)
>
> {
> // TODO
> }
>
> };
>
> public __value class VecDouble
> {
>
> public:
> void SetValue(VecFlo at vec)
>
> {
> // TODO
> }
>
> };
> }
>
> I've got the following error when compiling:
> error C2027: use of undefined type 'managedDll::Ve cDouble'
>
> Every think work fine if my SetValues methods have the signature

(Vec(Double

> | Float) &vec).
> The problem is that putting a '&' is not logical because I want to call > methods from C# code and with this signature I should write the

following

> code
>
> VecDouble vec = new VecDouble();
> vecFloat.SetVal ue(ref vec);
>
> Instead I want to call my methods in this way:
> vecFloat.SetVal ue(new VecDouble())
> The first solution is not acceptable !.
>
> Does anyone encounter the same problem ?
>
> Great thanks.
> Jerome
>
>