Including Templated C++ in Objective C

Question

Hello all,

I am trying to include a C++ library with quite a few templates into an objective C application.

It seems to perpetually choke on a few inline statements inside a shared library:

template <class T>
inline T MIN(T a, T b) { return a > b ? b : a; }

template <class T>
inline T MAX(T a, T b) { return a > b ? a : b; }

yielding the output:

expected unqualified-id before '{' token
expected `)' before '{' token

I am compiling with the options.

g++ -x objective-c++ -Wall -O3 -I. -c demod_gui.m -o demod_gui

All the other templates seem to compile fine, any idea what could be wrong here? Thanks in advance for any help.

Answer 1

There are already macros MIN and MAX defined in Foundation/NSObjCRuntime.h.

#if !defined(MIN)
    #define MIN(A,B)    ({ __typeof__(A) __a = (A); __typeof__(B) __b = (B); __a < __b ? __a : __b; })
#endif

#if !defined(MAX)
    #define MAX(A,B)    ({ __typeof__(A) __a = (A); __typeof__(B) __b = (B); __a < __b ? __b : __a; })
#endif

So your definition becomes

template <class T>
inline T ({ __typeof__(T a) __a = (T a); __typeof__(T b) __b = (T b); __a < __b ? __a : __b; }) { return a > b ? b : a; }

which is obviously invalid.

Why not use std::max and std::min?