Calling Managed functions from unmanaged class

[Amit Dedhia]

Hi All

I have a VC++ 2005 MFC application with all classes defined as
unmanaged classes. I want to write my application data in xml format.
Since ADO.NET has buit in functions available for this, I want to use
it. Is it possible to call Managed class functions from Unmanaged
class? How to do it?

I did something like this.
I declared a managed class (in C++ CLI) called as MyManagedClass whose
public interface has functions to write application data in XML format.
It internally uses ADO.NET classes to achieve this. This class is
declared in a seperate dll compiled with '\clr' option.

Now I created an unmanaged wrapper class which wraps the managed class
(defined in the same dll as that of managed class). The unmanaged
wrapper, call it as MyUnmanagedWrap per, has a data member declared as

gcroot<Object^h andleToManagedC lass;

This is declared in the top of the class. It has wrapper methods whose
implementation is something like this:

void MyUnmanagedWrap per::Method1()
{
(*this)->Method1();
}

and then I have...

class MyApplicationCl ass
{
MyUnmanagedWrap perInstance.Met hod1();
}

Everything complies well. However, when the above method is run, I get
Access Violation error. It does not even go inside the method.

Can anyone tell why there is access violation?

Best regards
Amit Dedhia

[Noah Roberts]

Re: Calling Managed functions from unmanaged class

Your question is off topic in comp.lang.c++

[Ben Voigt]

Re: Calling Managed functions from unmanaged class


"Amit Dedhia" <amitdedhia@yah oo.comwrote in message
news:1160608594 .944640.298370@ i3g2000cwc.goog legroups.com...

Hi All
>
I have a VC++ 2005 MFC application with all classes defined as
unmanaged classes. I want to write my application data in xml format.
Since ADO.NET has buit in functions available for this, I want to use
it. Is it possible to call Managed class functions from Unmanaged
class? How to do it?
>
I did something like this.
I declared a managed class (in C++ CLI) called as MyManagedClass whose
public interface has functions to write application data in XML format.
It internally uses ADO.NET classes to achieve this. This class is
declared in a seperate dll compiled with '\clr' option.
>
Now I created an unmanaged wrapper class which wraps the managed class
(defined in the same dll as that of managed class). The unmanaged
wrapper, call it as MyUnmanagedWrap per, has a data member declared as
>
gcroot<Object^h andleToManagedC lass;

Should be
gcroot<MyManage dClass^handleTo ManagedClass;

>
This is declared in the top of the class. It has wrapper methods whose
implementation is something like this:
>
void MyUnmanagedWrap per::Method1()
{
(*this)->Method1();

Should be
handleToManaged Class->Method1();

}
>
and then I have...
>
class MyApplicationCl ass
{
MyUnmanagedWrap perInstance.Met hod1();
}
>
Everything complies well. However, when the above method is run, I get
Access Violation error. It does not even go inside the method.
>
Can anyone tell why there is access violation?

Where is handleToManaged Class initialized? Initially it will hold a
nullptr. Testing a gcroot for nullptr is a pain, try:
(handleToManage dClass.operator->() != nullptr)

>
Best regards
Amit Dedhia
>

[Duane Hebert]

Re: Calling Managed functions from unmanaged class


"Noah Roberts" <roberts.noah@g mail.comwrote in message
news:1160608840 .838895.315300@ m7g2000cwm.goog legroups.com...

Your question is off topic in comp.lang.c++
>

I mostly prefer to call "unmanaged" native.
Unless, of course, you prefer to not manage your
code unless MS does it for you. <g>

[Amit Dedhia]

Re: Calling Managed functions from unmanaged class


Ben Voigt wrote:

"Amit Dedhia" <amitdedhia@yah oo.comwrote in message
news:1160608594 .944640.298370@ i3g2000cwc.goog legroups.com...

Hi All

I have a VC++ 2005 MFC application with all classes defined as
unmanaged classes. I want to write my application data in xml format.
Since ADO.NET has buit in functions available for this, I want to use
it. Is it possible to call Managed class functions from Unmanaged
class? How to do it?

I did something like this.
I declared a managed class (in C++ CLI) called as MyManagedClass whose
public interface has functions to write application data in XML format.
It internally uses ADO.NET classes to achieve this. This class is
declared in a seperate dll compiled with '\clr' option.

Now I created an unmanaged wrapper class which wraps the managed class
(defined in the same dll as that of managed class). The unmanaged
wrapper, call it as MyUnmanagedWrap per, has a data member declared as

gcroot<Object^h andleToManagedC lass;

>
Should be
gcroot<MyManage dClass^handleTo ManagedClass;
>

This is declared in the top of the class. It has wrapper methods whose
implementation is something like this:

void MyUnmanagedWrap per::Method1()
{
(*this)->Method1();

Should be
handleToManaged Class->Method1();
>

}

and then I have...

class MyApplicationCl ass
{
MyUnmanagedWrap perInstance.Met hod1();
}

Everything complies well. However, when the above method is run, I get
Access Violation error. It does not even go inside the method.

Can anyone tell why there is access violation?

Where is handleToManaged Class initialized? Initially it will hold a
nullptr. Testing a gcroot for nullptr is a pain, try:
(handleToManage dClass.operator->() != nullptr)

Ok Ben...I got the point

Regarding initialization of the object, I would have a static method in
MyManagedClass which returns an instance of iteself. I will call this
method in ctor of the MyUnmanagedWrap per. However, I still have one
question. I have both these classes defined in the same managed dll
(compiled with /clr option). How do I use this dll (and its classes)
from say an MFC dialog based application client?

>
>

Best regards
Amit Dedhia

[Ben Voigt]

Re: Calling Managed functions from unmanaged class


"Amit Dedhia" <amitdedhia@yah oo.comwrote in message
news:1160608594 .944640.298370@ i3g2000cwc.goog legroups.com...

Hi All
>
I have a VC++ 2005 MFC application with all classes defined as
unmanaged classes. I want to write my application data in xml format.
Since ADO.NET has buit in functions available for this, I want to use
it. Is it possible to call Managed class functions from Unmanaged
class? How to do it?
>
I did something like this.
I declared a managed class (in C++ CLI) called as MyManagedClass whose
public interface has functions to write application data in XML format.
It internally uses ADO.NET classes to achieve this. This class is
declared in a seperate dll compiled with '\clr' option.
>
Now I created an unmanaged wrapper class which wraps the managed class
(defined in the same dll as that of managed class). The unmanaged
wrapper, call it as MyUnmanagedWrap per, has a data member declared as
>
gcroot<Object^h andleToManagedC lass;

Should be gcroot<MyManage dClass^handleTo ManagedClass;

>
This is declared in the top of the class. It has wrapper methods whose
implementation is something like this:
>
void MyUnmanagedWrap per::Method1()
{
(*this)->Method1();

Should be handleToManaged Class->Method1();

Thought I saw this exact same question with the exact same broken code a
week ago.

}
>
and then I have...
>
class MyApplicationCl ass
{
MyUnmanagedWrap perInstance.Met hod1();
}
>
Everything complies well. However, when the above method is run, I get
Access Violation error. It does not even go inside the method.
>
Can anyone tell why there is access violation?

There is an access violation because in some code you have not shown us, you
are performing a bad cast and trying to use an object as a type it isn't.

Does your unmanaged class constructor set handleToManaged Class or leave it
as nullptr?

>
Best regards
Amit Dedhia
>