What is the “Execute Around” idiom?

Question

What is this \"Execute Around\" idiom (or similar) I\'ve been hearing about? Why might I use it, and why might I not want to use it?

Answer 1

The Execute Around idiom is used when you find yourself having to do something like this:

//... chunk of init/preparation code ...
task A
//... chunk of cleanup/finishing code ...

//... chunk of identical init/preparation code ...
task B
//... chunk of identical cleanup/finishing code ...

//... chunk of identical init/preparation code ...
task C
//... chunk of identical cleanup/finishing code ...

//... and so on.

In order to avoid repeating all of this redundant code that is always executed "around" your actual tasks, you would create a class that takes care of it automatically:

//pseudo-code:
class DoTask()
{
    do(task T)
    {
        // .. chunk of prep code
        // execute task T
        // .. chunk of cleanup code
    }
};

DoTask.do(task A)
DoTask.do(task B)
DoTask.do(task C)

This idiom moves all of the complicated redundant code into one place, and leaves your main program much more readable (and maintainable!)

Take a look at this post for a C# example, and this article for a C++ example.