CODEWITHSUNDEEP
c++
Vivek Goel
Vivek Goel

Reputation: 24150

What is the best way for giving callback for logging ?

I have third party library which calls an macro for logging. Inside that macro they are using fprintf for logging. I am thinking about modifying the code to define a custom callback for logging, but I am not sure what will be best way.

Solution I want is:

So I am looking for some type of static function with default definition which I can override if I want.

What will be the best way of doing this ? As we can't overload static function so everyone needs to define their definition of the logging function.

Upvotes: 1

Views: 2378

Answers (2)

Mats Petersson
Mats Petersson

Reputation: 129374

Something like this:

typedef void (*logfuncp)(...);

logfuncp callbackfuncp = NULL;

void logfunction(...)
{
   if (callbackfuncp) 
       callbackfuncp(...);
   else
       fprintf(logfile, ...);
}


void setcustomlogfunction(logfuncp newcallback)
{
    callbackfuncp = newcallback;
}

should work. The ... represent your logging arguments, which of course could be var-args using that real ... C syntax, but doesn't have to be. All depends on what your logging is.

Upvotes: 1

Icarus3
Icarus3

Reputation: 2350

Last time when I had similar problem, I used function pointers.

Let the logger call the function using function pointer.

By default set the pointer to your default method ( which is calling fprintf ).

If user want to override that behavior they will use their own functions.

....just another solution

Upvotes: 0

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