On Sun, May 2, 2010 at 3:59 AM, Christopher Zimmermann
<madroach@zakweb.de> wrote:
quoted text
> On Sat, 1 May 2010 14:11:22 +0200 Marc Espie wrote:
>
>> On Sat, May 01, 2010 at 11:39:00AM +0200, Christopher Zimmermann wrote:
>> > Hi,
>> >
>> > the following piece of code compiles fine using g++ 4.2.4, but
>> > fails using g++ 3.3.5 in the base system:
>> >
>> > error: operands to ?: have different types
>> >
>> > It is part of ptlib, which is the base library for opal, which in
>> > turn is needed for ekiga, which I'm trying to port.
>> >
>> > What is your suggestion? Can anyone think of a workaround for
>> > this or should I just compile it using eg++ 4.2.4 ?
>> >
>> >
>> > Christopher
>> >
>> >
>> > #include<err.h>
>> >
>> > #define WarnIfNULL(x) ((x) ? (x) : (warn("blub"),(x)))
>> >
>> > class A
>> > {
>> >   protected:
>> >     int a;
>> > };
>> >
>> > class B : A
>> > {
>> >   public:
>> >     void blub()
>> >     {
>> >          WarnIfNULL(A::a);
>> >     }
>> > };
>>
>> Why do some C++ programmer still use macros where they're not needed ?
>> bunch of idiots, let them stay with C.
>>
>> #include<err.h>
>>
>> template<typename T>
>> inline T WarnIfNULL(T x)
>> {
>>       if (!x)
>>               warn("blub");
>>       return x;
>> }
>>
>> class A
>> {
>>   protected:
>>     int a;
>> };
>>
>> class B : A
>> {
>>   public:
>>     void blub()
>>     {
>>          WarnIfNULL(A::a);
>>     }
>> };
>>
>
> ok, thanks. That seems to be the solution, still I have to wrap it in a
macro, because I need __LINE__, __FILE__, __CLASS__...


You example obviously isn't showing the exact usage you require. I
imagine the macro is being used in assignments, not just in the blub()
method as you display.


Cheers,
--patrick

$ cat fuck.c++
#include <stdlib.h>
#include <err.h>

#include <iostream>

#define WarnIfNULL(x)	((!(x) && ((void)warnx("blub"),1)) ? (x) : (x))


class A {
protected:
	int	a;
};

class B : public A {
public:
	void	blub(void) { WarnIfNULL(A::a); }
};

int
main(int argc, char *argv[])
{
	int	bs = 10;
	B	cxxsucks;

	cxxsucks.blub();

	bs = WarnIfNULL(100);
	::std::cout << "bullshit: " << bs << ::std::endl;

	exit(0);
}
$ c++ fuck.c++
/usr/lib/libstdc++.so.49.0: warning: strcpy() is almost always
misused, please use strlcpy()
/usr/lib/libstdc++.so.49.0: warning: strcat() is almost always
misused, please use strlcat()
$ ./a.out
a.out: blub
bullshit: 100