Calling C++ from C/Eiffel

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2 total messages Started by Paul Des Rivieres Wed, 20 Dec 1995 18:22

#1112

Author: Paul Des Rivieres
Date: Wed, 20 Dec 1995 18:22

36 lines
1922 bytes

During the summer I contacted ISE support staff about how to call
C++ from Eiffel.  They responsed that it was impossible because
there was no way to call the C++ constructor.  Since I have a C++
class interface to a mission critical C++ application one of my
co-workers researched and found a solution.  Add the following
routines to the C++ class:

ClassName * ClassName::init_object (void)
{
   ClassName *cp;

   if (!(cp = (ClassName *) malloc(sizeof(ClassName))))
      return NULL;
   *cp = ClassName();
   return cp;
}

void ClassName::free_object (ClassName *cp)
{
   free(cp);
}

Then compile the C++ class keeping the interm C file (use +i for
the CenterLine compiler).  Make note of the names of the C routines
corresponding to the C++ routines.  In C/Eiffel call the C routine
corresponding to ClassName::init_object then for the original C++
routines call the corresponding C routines with ClassName *cp as the
first parameter.
Note: In Eiffel it is possible to have ClassName::free_object called
with the object is garbage collected; inherit from MEMORY add redefine
dispose to call ClassName::free_object (note: use C version's name).
 
---------------------------------------------------------------
 Paul Des Rivieres   Senior Computer Analyst/Programmer
 Communications Security Establishment, Govt of Canada, Ottawa
 pdesrivi@cse.dnd.ca  Voice: (613)991-8796  Fax: (613)991-8811

Re: Calling C++ from C/Eiffel

#1123

Author: vlad
Date: Sun, 24 Dec 1995 22:50

44 lines
2027 bytes

Paul Des Rivieres <pdesrivi@cse.dnd.ca> wrote:

>During the summer I contacted ISE support staff about how to call
>C++ from Eiffel.  They responsed that it was impossible because
>there was no way to call the C++ constructor.  Since I have a C++
>class interface to a mission critical C++ application one of my
>co-workers researched and found a solution.  Add the following
>routines to the C++ class:

>ClassName * ClassName::init_object (void)
>{
>   ClassName *cp;

>   if (!(cp = (ClassName *) malloc(sizeof(ClassName))))
>      return NULL;
>   *cp = ClassName();
>   return cp;
>}

>void ClassName::free_object (ClassName *cp)
>{
>   free(cp);
>}

>Then compile the C++ class keeping the interm C file (use +i for
>the CenterLine compiler).  Make note of the names of the C routines
>corresponding to the C++ routines.  In C/Eiffel call the C routine
>corresponding to ClassName::init_object then for the original C++
>routines call the corresponding C routines with ClassName *cp as the
>first parameter.
>Note: In Eiffel it is possible to have ClassName::free_object called
>with the object is garbage collected; inherit from MEMORY add redefine
>dispose to call ClassName::free_object (note: use C version's name).
> 
>---------------------------------------------------------------
> Paul Des Rivieres   Senior Computer Analyst/Programmer
> Communications Security Establishment, Govt of Canada, Ottawa
> pdesrivi@cse.dnd.ca  Voice: (613)991-8796  Fax: (613)991-8811

I use simmilar approach, when I want to access C++ library from
Smalltalk.


Vlastimil Adamovsky

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