Passing values to atexit

Question

I want to push a series of clean up functions as they are needed. I was using atexit to do this for one cleanup function without any parameters, but I am not sure how to expand this approach to more then one clean up function. I am not very familiar with boost::bind, but assumed it would be a good idea as that is how I binded my functions to threads...

In c++ I am trying to get the following to work:

Function Definition

static void closeAnimation(string prefix="");// static member of fileWriter

Code:

atexit(boost::bind(fileWriter::closeAnimation, "0")); // I want to first prefix to be "0"

The error:

cannot convert ‘boost::_bi::bind_t<void, void (*)(std::basic_string<char>), boost::_bi::list1<boost::_bi::value<const char*> > >’ to ‘void (*)()’ for argument

Thanks in advance!

Answer 1

There is no "1 line solution without complicating your code".

The worst solution is to store that parameter in a global variable, and retrieve it in the atexit handler

Since you're using C++, the destructor of a static variable could also serve as an atexit handler. Then you can pass parameter at the constructor of that static variable for parametrization, e.g.

struct AtExitAnimationCloser
{
    const char* _which_param;

    AtExitAnimationCloser(const char* which_param) : _which_param(which_param) {}
    ~AtExitAnimationCloser() { FileWriter::closeAnimation(_which_param); }
};

void f()
{
    printf("entering f\n");

    static AtExitAnimationCloser s0 ("0"); // registers closeAnimation("0") at exit
    static AtExitAnimationCloser s1 ("1"); // registers closeAnimation("1") at exit

    printf("leaving f\n");
}

Demonstration: http://www.ideone.com/bfYnY

Note that static variables are bound to their name, so you cannot say

for (it = vecs.begin(); it != vecs.end(); ++ it)
{
   static AtExitAnimationCloser s (*it);
}

to call atexit for all the content. But you could make the static variable itself take whole range

static AnotherAtExitAnimationCloser s (vecs.begin(), vecs.end())

Finally, with idiomatic C++ I don't think you need to use these tricks... You could store a vector of types T, which on destruction ~T calls fileWriter::closeAnimation.