How can I implement assert macro as a method? - c++

Question

I want implement assert macro as a method in C++ like .NET Framewrk.
For example in C# we can invoke assert method like this:
Debug.Assert(index > -1);
and I want implement assert something like this:
#include <assert.h>
class debug
{
public:
static void my_asset(<condition>) // like assert macro
{
// ?
}
};
When using this class:
debug::my_asset(index > -1); // Actually should be called assert(index > -1);
Thanks
Edit:
I want when invoking debug::my_asset(index > -1);, It shows correct file name and line number, and it works like C++ asset macro.

Answer 1

There are several features of assert assert (in <assert.h> or <cassert>) that are of interest:
that when you're compiling a release build, the assert tests aren't evaluated at all.
the error message printed when an assertion fails can tell you the file and line number where your assertion failed
it can also tell you the exact code that failed.
You can't do these in C++ without using a macro.

Answer 2

The only way to get the line number, file, and text version is via macro. However:
#include <assert.h>
class debug
{
public:
static void my_assert(bool passed, const char* assert, const char* file, long line)
{
if (passed == false)
std::cout<<"failed assert "<<assert<<" in "<<file<<" at "<<line<<".\n";
}
#ifdef NDEBUG
#define myassert(x) my_assert(true, "", "", 0)
#else
#define myassert(x) my_assert(x, #x , __FILE__, __LINE__ )
#endif
};
int main() {
debug::myassert(sizeof(int)==4);
return 0,
}
This code works in an oddball way. The first x is the assert expression itself, evaluating to true or false, to tell my_assert what to do. The #x is a magic preprocessor command that makes a char* version of x, so we can display it. __FILE__ is replaced with the filename, and __LINE__ is replaced with the line number. (Since it's a macro, it has the same line number as the calling function).
When you type debug::myassert(sizeof(int)==4);, the preprocessor says "I know what myassert(whatever) is!" and replaces it. So it replaces it all with: debug::my_assert(sizeof(int)==4, "sizeof(int)==4", "main.cpp", 27);, which is a valid line of code. So if sizeof(int) is 8 for instance (it is on some machines), the first parameter is false, and the line is displayed "failed assert sizeof(int)==4 in main.cpp at 27."

Answer 3

static void my_asset(bool cond) // like assert macro
{
::assert(cond);
}
Doesn't work?

Answer 4

You could
void debug::my_assert(bool cond) {
ASSERT(cond);
}
This would work in that it would cause an exception when the assertion failed.
It's a little less helpful than the macro because my_assert can't see what the condition was that failed -- you'll get an assertion failure but no useful explanation (though you'll get an accurate stack trace in a debugger).
Also see Ken's reasons why a macro is more helpful.