Simple Macro Function Pointer Trick...

[Chris Thomasson]

I was wondering if the following technique will produce undefined behavior:
_______________
#include <cstdio>

#define CALL_MACRO_FUNC TION(func_ptr)f unc_ptr()

#define MY_MESSAGE() "Press <ENTERto exit."

int main(void) {
puts(CALL_MACRO _FUNCTION(MY_ME SSAGE));
getchar();
return 0;
}

_______________


I define 'MY_MESSAGE' as a macro function and only pass the name of it to
'CALL_MACRO_FUN CTION' which in turn uses the name to actually invoke it. The
name of a macro function is analogous to a function pointer. This is useful
when you need to have precise control over when a macro will actually
expand.


--
Chris M. Thomasson

http://appcore.home.comcast.net

[Chris Thomasson]

Re: Simple Macro Function Pointer Trick...

"James Kanze" <james.kanze@gm ail.comwrote in message
news:1189845690 .693508.110400@ n39g2000hsh.goo glegroups.com.. .
On Sep 14, 4:16 pm, "Chris Thomasson" <cris...@comcas t.netwrote:

>I was wondering if the following technique will produce undefined
>behavior:
>______________ _
>#include <cstdio>

[...]

>______________ _

Not related to your actual question, but the above shouldn't
compile with a conformant implementation of <cstdio>.

[...]

DOH! Ah crap. Of course your correct. Here is some better code:

_______________ _
#include <cstdio>

#define CALL_MACRO_FUNC TION(func_ptr)f unc_ptr()

#define MY_MESSAGE() "Press <ENTERto exit."

int main(void) {
{
using namespace std;
puts(CALL_MACRO _FUNCTION(MY_ME SSAGE));
getchar();
}

return 0;
}

_______________ _

>I define 'MY_MESSAGE' as a macro function and only pass the
>name of it to 'CALL_MACRO_FUN CTION' which in turn uses the
>name to actually invoke it. The name of a macro function is
>analogous to a function pointer. This is useful when you need
>to have precise control over when a macro will actually
>expand.

It should work.

Yeah. I agree. BTW, thank you for you response.