Note that RTMS is a macro

manus_eiffel — Thu, 19 Jun 2008 22:43:37 -0700

Note that RTMS is a macro and evaluate twice its argument, so for efficiency it should be:

cpp_get_text: STRING is

        -- Get some dummy text

    external

        "C++ inline use <string>"

    alias

        "[

         std::string a = "dummy";

         char *c_str = (char*) a.c_str();

         return RTMS(c_str);

        "]

    end

After having a problem with

patrickr — Wed, 18 Jun 2008 13:27:07 -0700

After having a problem with creating a STRING from a std::string (c++): Here's the solution

cpp_get_text: STRING is

        -- Get some dummy text

    external

        "C++ inline use <string>"

    alias

        "[

         std::string a = "dummy";

         return RTMS(((char*)a.c_str()));

        "]

    end

C/C++ calls and callbacks

clemahieu — Mon, 16 Jun 2008 09:33:35 -0700

Most existing examples on how to do external calls contain a lot of English explanation which can distract people, like myself, who learn by example. This is intended to be a compilable, terse example of how to call in and out of C/C++.

This is a C example:

class

    APPLICATION

create

    make

feature -- Initialization

    make is

            -- Run application.

        do

            create callback

            c_set_routine (callback.routine)

            c_set_object ($callback)

            c_do_callback

        end

    callback: CALLABLE

feature{NONE}

    c_set_routine (routine: POINTER) is

        external

            "C inline use %"application.h%""

        alias

            "c_set_routine ($routine);"

        end

    c_set_object (obj: POINTER) is

        external

            "C inline use %"application.h%""

        alias

            "c_set_object ($obj);"

        end

    c_do_callback is

        external

            "C inline use %"application.h%""

        alias

            "c_do_callback();"

        end

end -- class APPLICATION

class

    CALLABLE

feature

    inside is

        local

            current_addr: POINTER

        do

            current_addr := $Current

            io.put_string ("We're inside at address: " + current_addr.to_integer_32.out)

            io.put_new_line

        end

    routine: POINTER is

        do

            result := $inside

        end

end

application.h:

#include "eif_eiffel.h"

EIF_OBJECT obj = NULL;

EIF_POINTER routine;

void c_set_routine (EIF_POINTER routine_a)

{

    routine = routine_a;

}

void c_set_object (EIF_REFERENCE obj_a)

{

    if(obj != NULL)

    {

        eif_wean (obj);

    }

    obj = eif_protect (obj_a);

}

void c_do_callback ()

{

    ((void (*) (EIF_REFERENCE)) routine) (eif_access (obj));

}

This is a similar C++ example:

class

    APPLICATION

create

    make

feature -- Initialization

    make is

        do

            create call

            cpp_obj := c_new

            c_set_routine (cpp_obj, call.routine)

            c_set_object (cpp_obj, $call)

            c_do_callback (cpp_obj)

        end

    cpp_obj: POINTER

    call: CALLABLE

feature {NONE}

    c_new: POINTER is

        external

            "C++ inline use %"application.h%""

        alias

            "[

                return new test_class;

            ]"

        end

    c_set_routine (obj: POINTER routine: POINTER) is

        external

            "C++ inline use %"application.h%""

        alias

            "((test_class *) ($obj))->c_set_routine ($routine);"

        end

    c_set_object (obj: POINTER e_obj: POINTER) is

        external

            "C++ inline use %"application.h%""

        alias

            "((test_class *) ($obj))->c_set_object ((EIF_REFERENCE)$e_obj);"

        end

    c_do_callback (obj: POINTER) is

        external

            "C++ inline use %"application.h%""

        alias

            "((test_class *) ($obj))->c_do_callback();"

        end

end

class

    CALLABLE

feature

    inside is

        local

            current_addr: POINTER

        do

            current_addr := $Current

            io.put_string ("We're inside at address: " + current_addr.to_integer_32.out)

            io.put_new_line

        end

    routine: POINTER is

        do

            result := $inside

        end

end

application.h:

#include "eif_eiffel.h"

class test_class

{

public:

    test_class();

    ~test_class();

    EIF_OBJECT obj;

    EIF_POINTER routine;

    void c_set_object (EIF_REFERENCE obj_a);

    void c_set_routine (EIF_POINTER routine_a);

    void c_do_callback ();

};

test_class::test_class()

{

}

void test_class::c_set_object (EIF_REFERENCE obj_a)

{

    if (obj != NULL)

    {

        eif_wean (obj);

    }

    obj = eif_protect (obj_a);

}

void test_class::c_set_routine (EIF_POINTER routine_a)

{

    routine = routine_a;

}

void test_class::c_do_callback ()

{

    ((void (*) (EIF_REFERENCE)) routine) (eif_access (obj));

}

eiffelroom - C/C++ calls and callbacks - Comments

Note that RTMS is a macro

After having a problem with

C/C++ calls and callbacks