What is the best way for giving callback for logging ?
<p>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.</p>

<p>Solution I want is:</p>

<ul>
<li>User can define a callback for logging. </li>
<li>If callback is not define use fprint. </li>
</ul>

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

<p>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. </p>
