Thread: Re-Written Assert, can't get __FUNCTION__ or __func__ to work

I have re-written assert to serve my own purpose. I want to hide debug implementation details from the "callers" using functions. Basically, a string parameter in my functions will be hidden from them and that string will contain debug information. I want my assert's to do the following:

1)failed statement, line, file, function
2)line, file, function (where call originated from)

This is because my code i need to test is seperate from my "main" application.

example:

Code:

main.c    //origin of call
int main()
{
    dosomething();
}

Code:

dosomething.c //where code being tested is
int dosomething()
{
   myassert( statement ); //tell me statement, function, line, file (and origin line, file, function)
}

Here is what i've come up with, but the __FUNCTION__ or __func__ doesn't expand, it just prints as __FUNCTION__ or __func__.... The following is an example, in the same file but it is only an example!

Code:

#define STRINGIFY(x) #x
#define TOSTRING(x) STRINGIFY(x)
#define LOCATION  __FILE__ ":" TOSTRING(__LINE__)  //<---I want the __func__ here...

#ifdef NDEBUG
#define CHECK(ignore)((void) 0)
#else
#define CHECK(x)                                                                \
{                                                                               \
        if( !(x) )                                                              \
        {                                                                       \
                fprintf(stderr, "%s %s %s", TOSTRING(x), LOCATION, origin );    \
                exit(1);                                                        \
        }                                                                       \
}
#endif

//when caller uses this function, they don't know about the "char *origin" parameter
void myfunction( char *origin, int index, int value )
{
        CHECK( index == 2 );
}

#define myfunction(...) myfunction(LOCATION,__VA_ARGS__) //hide implementation details

int main ()
{
       myfunction(1,2); //use the same way whether debugging is on or off

       return( 0 );
}

Thanks in advance..Oh, and the macros __FUNCTION__ etc.. do work on their own if I were to use printf("%s", __FUNCTION__); but that's not what i'm looking for. I would like to append it to my define, thanks.

This might be better served in the Windows forum since this is not a standard (ANSI) macro expansion. That said a quick Google reveals that this will not expand if the /EP or /P compile option is specified....

HTH

I would have to dig to get an answer since I have never tried this. If I find something I will get back to you...this BTW is any I like adhering to language standards, an opinion not shared by all.

Later
J.

Have you read this? GCC Function names

Is stringification, ... (ellipsis), and __FUNCTION__ C99 compliant? I don't want to be writing code thats gonna crap out across platforms.

I can simply use __FUNCTION__ in my "ASSERT" define, but than I only get the function where the assertion is firing, not the end of the world, because I will know the file and line number of the originating call. I guess i'm just being picky and looking for as much information as possible. Should i be doing conditional compilation based on compiler present and version etc...?

The link you pointed me to mentioned compiler version changed from string literal to variable for __FUNCTION__, so than I should be doing conditional compilation on how I append __FUNCTION__ to my define, but i'm still puzzled on how I add it to the define and get it to work properly.

@Tempster: depends on how many/which platforms you are trying to support as well as compiler (and by extension language versions)....also I wanted to add where I said that the FUNCTION bit was MS-specific, that came right off of the MSDN. I did not know that GCC was trying to support it too. WRT to stringification, let me look when I get my chores done (holiday relatives arriving tomorrow so have meat-space things to get done...meh)

Originally Posted by tempster09

Is stringification, ... (ellipsis), and __FUNCTION__ C99 compliant? I don't want to be writing code thats gonna crap out across platforms.

Yes, dunno (in this context), no (unless I missed something again).

don't rush, it's the holidays, don't make me a priority lol.

I'm only working with GCC probably 3.0+, across linux platforms. I think __FUNCTION__ is supported by GCC and expanded to a string literal, and after 3.0 or something it was treated as a variable i.e. __func__.

printf("%s", __FUNCTION__); gives me what I need for the context of the function that's failing, I just can't get it to work in my Macro (which i want to use on any function), maybe because it isn't defined in that context....i'm not sure but it only gives me the macro itself i.e. "__FUNCTION__" is printed to screen when included in my macro.

Laserlight: i'm sorry I don't understand your response.

Basically, i guess i need a way to concatenate two const char *, because __func__ is a variable and Ive already got a string containing the LINE and FILE....

#define myfunction(...) myfunction(strncat(LOCATION, __func__, strlen(__func__) ), __VA_ARGS__) //Results in an error at memcopy (debugging i see both strings are correct, but i can not read the source file the error occurs at

Originally Posted by tempster09

don't rush, it's the holidays, don't make me a priority lol.

Yes but as the wise man says "Coding is more fun than mopping floors"

I'm only working with GCC probably 3.0+, across linux platforms. I think __FUNCTION__ is supported by GCC and expanded to a string literal, and after 3.0 or something it was treated as a variable i.e. __func__.

It might be helpful to know your *exact* compiler version since according to the link I posted:

These identifiers are not preprocessor macros. In GCC 3.3 and earlier, in C only, __FUNCTION__ and __PRETTY_FUNCTION__ were treated as string literals; they could be used to initialize char arrays, and they could be concatenated with other string literals. GCC 3.4 and later treat them as variables, like __func__. In C++, __FUNCTION__ and __PRETTY_FUNCTION__ have always been variables.

Plus I know I don't have any compiler in the house with a version less than 4.x....

J.

Ya, my current compiler is at 4.xx as well.

RE:
Basically, i guess i need a way to concatenate two const char *, because __func__ is a variable and Ive already got a string containing the LINE and FILE....

#define myfunction(...) myfunction(strncat(LOCATION, __func__, strlen(__func__) ), __VA_ARGS__) //Results in an error at memcopy (debugging i see both strings are correct, but i can not read the source file the error occurs at

So im not sure what i'm doing wrong. It seems it just doesn't want to group these strings together, i can pass them as two seperate variables but this should be working