Stupid typedef question / g++

Stupid typedef question / g++

[SA]

Should this work?

// start
#include <stdio.h>
typedef int     TYPE1;
typedef int TYPE2;

void test(TYPE1);
void test(TYPE2);

void test(TYPE1 in){
                printf("Called via type1 %d\n",(int)in);
                        }

void test(TYPE2 in){
                printf("Called vis type2 %d\n",(int)in);
                        }

main(){
        test((TYPE1)10);
        test((TYPE2)20);
        }
// finish

Now I expected the typedefs and casts to enable correct function selection
but what I got was

g++ test.cc
test.cc: In function `void test (int)':
test.cc:12: redefinition of `void test (int)'
test.cc:8: `void test (int)' previously defined here

Which is what I would expect if I had used 
#define TYPE1 int
#define TYPE2 int
instead?

Comments, suggestions? I wanted to use the typedefing to control the function 
calling for elegance in my program.

Thanks SA

Re: Stupid typedef question / g++

[Ben Davis]

(Sorry if you get too many copies of this, SA. I got the address wrong for 
the mailing list, and I didn't know if you'd got your copy :)

On Friday 24 January 2003 3:17 pm, you wrote:
> Should this work?
>
> // start
> #include <stdio.h>
> typedef int     TYPE1;
> typedef int TYPE2;

typedef simply gives you a name by which to refer to a (possibly more 
complex) type. I'm afraid it doesn't offer any segregation between the types. 
You could remove the casts and your code would still be completely valid.

I too would be interested to know of a way of doing this...

Ben

Re: Stupid typedef question / g++

[Sebastian Huber]

Hi,
typedefs provide only type aliasses, they do not define new types. User 
defined types can be created via class (or struct) and in a more limited way 
with enums.

On Friday 24 January 2003 16:17, SA wrote:
> Should this work?
>
> // start
> #include <stdio.h>
> typedef int     TYPE1;
> typedef int TYPE2;
>
> void test(TYPE1);
> void test(TYPE2);
>
> void test(TYPE1 in){
>                 printf("Called via type1 %d\n",(int)in);
>                         }
>
> void test(TYPE2 in){
>                 printf("Called vis type2 %d\n",(int)in);
>                         }
>
> main(){
>         test((TYPE1)10);
>         test((TYPE2)20);
>         }
> // finish
>
> Now I expected the typedefs and casts to enable correct function selection
> but what I got was
>
> g++ test.cc
> test.cc: In function `void test (int)':
> test.cc:12: redefinition of `void test (int)'
> test.cc:8: `void test (int)' previously defined here
>
> Which is what I would expect if I had used
> #define TYPE1 int
> #define TYPE2 int
> instead?
>
> Comments, suggestions? I wanted to use the typedefing to control the
> function calling for elegance in my program.
>
> Thanks SA

Re: Stupid typedef question / g++

[John Love-Jensen]

Hi SA,

No, that will not work.  C++ does not have an "explicit typedef", rather it
has an aliasing typedef.

You can do something like this:
struct TYPE1 { int m; TYPE1(int in) : m(in) {} };
struct TYPE2 { int m; TYPE2(int in) : m(in) {} };

void test(TYPE1);
void test(TYPE2);

...et cetera.  You can add more convenience routines to the two types, to
make them spoof "being an int" as much as you require.

--Eljay